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    Metal-backed versus all-polyethylene unicompartmental knee arthroplasty: Proximal tibial strain in an experimentally validated finite element model. Scott C E H,Eaton M J,Nutton R W,Wade F A,Evans S L,Pankaj P Bone & joint research OBJECTIVES:Up to 40% of unicompartmental knee arthroplasty (UKA) revisions are performed for unexplained pain which may be caused by elevated proximal tibial bone strain. This study investigates the effect of tibial component metal backing and polyethylene thickness on bone strain in a cemented fixed-bearing medial UKA using a finite element model (FEM) validated experimentally by digital image correlation (DIC) and acoustic emission (AE). MATERIALS AND METHODS:A total of ten composite tibias implanted with all-polyethylene (AP) and metal-backed (MB) tibial components were loaded to 2500 N. Cortical strain was measured using DIC and cancellous microdamage using AE. FEMs were created and validated and polyethylene thickness varied from 6 mm to 10 mm. The volume of cancellous bone exposed to < -3000 µε (pathological loading) and < -7000 µε (yield point) minimum principal (compressive) microstrain and > 3000 µε and > 7000 µε maximum principal (tensile) microstrain was computed. RESULTS:Experimental AE data and the FEM volume of cancellous bone with compressive strain < -3000 µε correlated strongly: R = 0.947, R = 0.847, percentage error 12.5% (p < 0.001). DIC and FEM data correlated: R = 0.838, R = 0.702, percentage error 4.5% (p < 0.001). FEM strain patterns included MB lateral edge concentrations; AP concentrations at keel, peg and at the region of load application. Cancellous strains were higher in AP implants at all loads: 2.2- (10 mm) to 3.2-times (6 mm) the volume of cancellous bone compressively strained < -7000 µε. CONCLUSION:AP tibial components display greater volumes of pathologically overstrained cancellous bone than MB implants of the same geometry. Increasing AP thickness does not overcome these pathological forces and comes at the cost of greater bone resection.Cite this article: C. E. H. Scott, M. J. Eaton, R. W. Nutton, F. A. Wade, S. L. Evans, P. Pankaj. Metal-backed versus all-polyethylene unicompartmental knee arthroplasty: Proximal tibial strain in an experimentally validated finite element model. Bone Joint Res 2017;6:22-30. DOI:10.1302/2046-3758.61.BJR-2016-0142.R1. 10.1302/2046-3758.61.BJR-2016-0142.R1
    Is unicompartmental arthroplasty an acceptable option for spontaneous osteonecrosis of the knee? Bruni Danilo,Iacono Francesco,Raspugli Giovanni,Zaffagnini Stefano,Marcacci Maurilio Clinical orthopaedics and related research BACKGROUND:The literature suggests survivorship of unicompartmental knee arthroplasties (UKAs) for spontaneous osteonecrosis of the knee ranges from 93% to 97% at 10 to 12 years. However, these data arise from small series (23 to 33 patients), jeopardizing meaningful conclusions. QUESTIONS/PURPOSES:We determined (1) the longer-term survivorship of UKAs in a larger group of patients with spontaneous osteonecrosis of the knee; (2) their subjective, symptomatic, and functional outcomes; and (3) the percentage of failures and reasons for failures to identify relevant indications, contraindications, and technical parameters for treatment with a modern implant design. METHODS:We retrospectively evaluated all 84 patients with late-stage spontaneous osteonecrosis of the knee who had a medial UKA from 1998 to 2005. All patients had preoperative MRI to confirm the diagnosis, exclude metaphyseal involvement, and confirm the absence of major degenerative changes in the lateral and patellofemoral compartments. The mean age of the patients at surgery was 66 years and mean BMI was 28.9. We conducted Kaplan-Meier survival analysis using revision for any reason as the end point. Minimum followup was 63 months (mean, 98 months; range, 63-145 months). RESULTS:Ten-year survivorship was 89%. Ten revisions were performed; the most common reasons were subsidence of the tibial component (four) and aseptic loosening of the tibial component (three). No patient underwent revision for progression of osteoarthritis in the lateral or patellofemoral compartments. CONCLUSIONS:Our data suggest spontaneous osteonecrosis of the knee may be an indication for UKA, provided secondary osteonecrosis of the knee is ruled out, preoperative MRI documents the absence of disease in other compartments, and there is no overcorrection in any plane. LEVEL OF EVIDENCE:Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. 10.1007/s11999-012-2246-2
    A randomised trial of all-polyethylene and metal-backed tibial components in unicompartmental arthroplasty of the knee. Hutt J R B,Farhadnia P,Massé V,LaVigne M,Vendittoli P-A The bone & joint journal This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan-Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p < 0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23). This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components. 10.1302/0301-620X.97B6.35433
    Combined unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction. Tinius Marco,Hepp Pierre,Becker Roland Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Patients presenting anterior cruciate ligament (ACL) deficiency and isolated osteoarthritis of the medial compartment are treated either with biplanar osteotomy or with total knee arthroplasty (TKA). However, these patients between the forties and fifties are often very active in daily life and feel limited due to their knee. In order to follow the idea of preserving as much as possible from the joint, the concept of unicondylar joint replacement in conjunction with ACL reconstruction has been followed. There seems to be a limited experience with this concept. The purpose of the follow-up study was to evaluate the midterm clinical and functional outcome. METHODS:Twenty-seven patients were followed up for 53 months. The mean age of the 11 men and 16 women was 44 years. All patients were treated by combined unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction. RESULTS:The Knee Society Score improved significantly from 77.1 ± 11.6 points to 166.0 ± 12.1 points (P ≤ 0.01). No revision surgery was required and no radiolucent lines were observed on the radiographs at the time of follow-up. The anterior translation showed less than 5 mm in 24 patients and 5 mm in the remaining 3 patients. CONCLUSIONS:The midterm clinical data have shown that combined surgery of UKA and anterior cruciate ligament reconstruction has revealed promising results. The restored knee stability seems to prevent the failure of UKA. However, long-term follow-up studies are required in these patients who received partial joint replacement fairly early in their life. LEVEL OF EVIDENCE:IV. 10.1007/s00167-011-1528-7
    The tibial spine sign does not indicate cartilage damage in the central area of the distal lateral femoral condyle. Boettner Friedrich,Springer Bernhard,Windhager Reinhard,Waldstein Wenzel Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:A radiographic overlap of the lateral femoral condyle and the lateral tibial spine ('tibial spine sign') might indicate lateral compartment cartilage damage and might be considered a contraindication for unicompartmental knee arthroplasty (UKA). Therefore, the following research questions were asked: (1) does the presence of a 'tibial spine sign' on radiographs correlate with cartilage lesions on the medial aspect of the lateral femoral condyle on corresponding MRIs?; (2) do cartilage lesions on the medial aspect of the lateral femoral condyle indicate cartilage damage in the central area of the distal lateral femur?; and 3) is the 'tibial spine sign' impacted by the degree of varus deformity, the amount of coronal tibiofemoral subluxation or the functional status of the ACL? METHODS:One hundred consecutive knees with varus OA in 84 patients were prospectively included. The relationship of the lateral femoral condyle and the tibial spine was graded from 0 to 2 based on the degree of overlap on AP standing knee radiographs. On MRI, cartilage on the medial aspect of the lateral femoral condyle was assessed. Cartilage in the weight-bearing area of the distal lateral femur was analysed according to the OARSI system. RESULTS:The 'tibial spine sign' assessment correlated well with the degree of cartilage damage on the medial aspect of the lateral condyle (r = 0.7, p < 0.001) but did not impact histological OARSI grades in the central weight bearing area of the lateral condyle (n.s.). Mechanical varus and tibiofemoral subluxation were not associated (n.s.) with a positive tibial spine sign. Knees with suggestive ACL insufficiency on MRI had more often a positive tibial spine sign; however, this difference was not statistically significant (n.s.). CONCLUSION:A positive tibial spine sign does not indicate histologic cartilage damage in the central area of the distal lateral femur and may not be considered a contraindication for medial UKA. LEVEL OF EVIDENCE:Level III, diagnostic study. 10.1007/s00167-020-05881-1
    The coronal alignment after medial unicompartmental knee arthroplasty can be predicted: usefulness of full-length valgus stress radiography for evaluating correctability. Tashiro Yasutaka,Matsuda Shuichi,Okazaki Ken,Mizu-Uchi Hideki,Kuwashima Umito,Iwamoto Yukihide Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:We aimed to clarify whether the coronal alignment after medial unicompartmental knee arthroplasty (UKA) is predictable using preoperative full-length valgus stress radiography. METHODS:Thirty-seven consecutive patients with a mean age of 71.5 ± 7.0 years awaiting medial UKA were recruited. Full-length weight-bearing radiographs of the lower limbs were obtained pre- and postoperatively. Preoperative full-length valgus stress radiography in the supine position was also performed, and the transition of the hip-knee-ankle angle (HKAA) and the weight-bearing ratio were assessed. The tibia first cut technique was used, and the distal femur was cut parallel to the cutting surface of the proximal tibia during surgery. RESULTS:The mean postoperative HKAA was 2.0° ± 2.1° varus, and the mean weight-bearing ratio was 43.1 ± 7.7 %; each of these parameters demonstrated significantly strong correlations with the values on the preoperative valgus stress radiographs (p < 0.01), while the correlation between the postoperative alignment and the preoperative standing alignment without stress was moderate (p < 0.01). The postoperative alignment was slightly undercorrected compared to that observed on the valgus stress radiographs (p < 0.05), and no knees exhibited evident overcorrection compared to that on the valgus stress radiographs. CONCLUSION:Preoperative valgus stress radiography is useful for evaluating the correctability of varus deformities and predicting the postoperative coronal alignment. For clinical relevance, performing preoperative valgus stress radiography would help to more precisely select patients and, when combined with the tibia first cut technique, aid in achieving the expected knee alignment and avoid severe undercorrection or overcorrection. LEVEL OF EVIDENCE:Diagnostic study, Level II. 10.1007/s00167-014-3248-2
    Risk factors of post-operative malalignment in fixed-bearing medial unicompartmental knee arthroplasty. Ahn Ji Hyun,Kang Ho Won,Yang Tae Yeong,Lee Jang Yun International orthopaedics PURPOSE:The purpose of this study was to identify risk factors of post-operative malalignment in medial unicompartmental knee arthroplasty (UKA) using multivariate logistic regression. METHODS:We retrospectively enrolled 92 patients who had 127 medial UKAs. According to post-operative limb mechanical axis (hip-knee-ankle [HKA] angle), 127 enrolled knees were sorted into acceptable alignment with HKA angle within the conventional ± 3 degree range from a neutral alignment (n = 73) and outlier with HKA angle outside ± 3 degree range (n = 54) groups. Multivariate logistic regression was used to analyse risk factors including age, gender, body mass index, thickness of polyethylene tibial insert, pre-operative HKA angle, distal femoral varus angle (DFVA), femoral bowing angle (FBA), tibial bone varus angle (TBVA), mechanical distal femoral and proximal tibial angles, varus and valgus stress angles, size of femoral and tibial osteophytes, and femoral and tibial component alignment angles. RESULTS:Pre-operative DFVA, TBVA and valgus stress angle were identified as significant risk factors. As DFVA increased by one degree, malalignment was about 45 times probable (adjusted OR 44.871, 95 % CI 2.608-771.904). Shift of TBVA and valgus stress angle to a more varus direction were also significant risk factors (adjusted OR 13.001, 95 % CI 1.754-96.376 and adjusted OR 2.669, 95 % CI 1.054-6.760). CONCLUSIONS:Attention should be given to the possibility of post-operative malalignment during medial UKA in patients with a greater varus angle in pre-operative DFVA, TBVA and valgus stress angle, especially with a greater varus DFVA, which was the strongest predictor for malalignment. 10.1007/s00264-015-3014-1
    Minimally invasive surgery did not improve outcome compared to conventional surgery following unicompartmental knee arthroplasty using local infiltration analgesia: a randomized controlled trial with 40 patients. Essving Per,Axelsson Kjell,Otterborg Lena,Spännar Henrik,Gupta Anil,Magnuson Anders,Lundin Anders Acta orthopaedica BACKGROUND AND PURPOSE:There has recently been interest in the advantages of minimally invasive surgery (MIS) over conventional surgery, and on local infiltration analgesia (LIA) during knee arthroplasty. In this randomized controlled trial, we investigated whether MIS would result in earlier home-readiness and reduced postoperative pain compared to conventional unicompartmental knee arthroplasty (UKA) where both groups received LIA. PATIENTS AND METHODS:40 patients scheduled for UKA were randomized to a MIS group or a conventional surgery (CON) group. Both groups received LIA with a mixture of ropivacaine, ketorolac, and epinephrine given intra- and postoperatively. The primary endpoint was home-readiness (time to fulfillment of discharge criteria). The patients were followed for 6 months. RESULTS:We found no statistically significant difference in home-readiness between the MIS group (median (range) 24 (21-71) hours) and the CON group (24 (21-46) hours). No statistically significant differences between the groups were found in the secondary endpoints pain intensity, morphine consumption, knee function, hospital stay, patient satisfaction, Oxford knee score, and EQ-5D. The side effects were also similar in the two groups, except for a higher incidence of nausea on the second postoperative day in the MIS group. INTERPRETATION:Minimally invasive surgery did not improve outcome after unicompartmental knee arthroplasty compared to conventional surgery, when both groups received local infiltration analgesia. The surgical approach (MIS or conventional surgery) should be selected according to the surgeon's preferences and local hospital policies. ClinicalTrials.gov. (Identifier NCT00991445). 10.3109/17453674.2012.736169
    Correction of coronal alignment correlates with reconstruction of joint height in unicompartmental knee arthroplasty. Kuwashima U,Okazaki K,Tashiro Y,Mizu-Uchi H,Hamai S,Okamoto S,Murakami K,Iwamoto Y Bone & joint research OBJECTIVES:Because there have been no standard methods to determine pre-operatively the thickness of resection of the proximal tibia in unicompartmental knee arthroplasty (UKA), information about the relationship between the change of limb alignment and the joint line elevation would be useful for pre-operative planning. The purpose of this study was to clarify the correlation between the change of limb alignment and the change of joint line height at the medial compartment after UKA. METHODS:A consecutive series of 42 medial UKAs was reviewed retrospectively. These patients were assessed radiographically both pre- and post-operatively with standing anteroposterior radiographs. The thickness of bone resection at the proximal tibia and the distal femur was measured radiographically. The relationship between the change of femorotibial angle (δFTA) and the change of joint line height, was analysed. RESULTS:The mean pre- and post-operative FTA was 180.5° (172.2° to 184.8°) and 175.0° (168.5° to 178.9°), respectively. The mean δFTA was 5.5° (2.3° to 10.1°). The joint line elevation of the tibia (JLET) was 4.4 mm (2.1 to 7.8). The δFTA was correlated with the JLET (correlation coefficient 0.494, p = 0.0009). CONCLUSIONS:This study indicated that there is a significant correlation between the change of limb alignment and joint line elevation. This observation suggests that it is possible to know the requirement of elevation of the joint line to obtain the desired correction of limb alignment, and to predict the requirement of bone resection of the proximal tibia pre-operatively. Cite this article: Bone Joint Res 2015;4:128-133. 10.1302/2046-3758.48.2000416
    Revision Analysis of Robotic Arm-Assisted and Manual Unicompartmental Knee Arthroplasty. Cool Christina L,Needham Keith A,Khlopas Anton,Mont Michael A The Journal of arthroplasty BACKGROUND:The purpose of this study was to evaluate hospital admissions for revision surgeries associated with robotic arm-assisted unicompartmental knee arthroplasty (rUKA) vs manually instrumented UKA (mUKA) procedures. METHODS:Patients ≥18 years of age who received either a mUKA or a rUKA procedure were candidates for inclusion and were identified by the presence of appropriate billing codes. Procedures performed between March 1, 2013 and July 31, 2015 were used to calculate the rate of surgical revisions occurring within 24-months of the index procedure. Following propensity matching, 246 rUKA and 492 mUKA patients were included. Revision rates and the associated costs were compared between the two cohorts. The Mann-Whitney U test was used to compare continuous variables, and Fisher's exact tests was used to analyze discrete categorical variables. RESULTS:At 24 months after the primary UKA procedure, patients who underwent rUKA had fewer revision procedures (0.81% [2/246] vs 5.28% [26/492]; P = .002), shorter mean length of stay (2.00 vs 2.33 days; P > .05), and incurred lower mean costs for the index stay plus revisions ($26,001 vs $27,915; P > .05) than mUKA patients. Length of stay at index and index costs were also lower for rUKA patients (1.77 vs 2.02 days; P = .0047) and ($25,786 vs $26,307; P > .05). CONCLUSIONS:The study results demonstrate that patients who underwent rUKA had fewer revision procedures, shorter length of stay, and incurred lower mean costs (although not statistically different) during the index admission and at 24 months postoperatively. These results could be important for payers as the prevalence of end-stage knee osteoarthritis increases alongside the demand for cost-efficient treatments. 10.1016/j.arth.2019.01.018
    Residual Symptoms and Function After Unicompartmental and Total Knee Arthroplasty: Comparable to Normative Controls? Nam Denis,Berend Michael E,Nunley Ryan M,Della Valle Craig J,Berend Keith R,Lombardi Adolph V,Barrack Robert L The Journal of arthroplasty BACKGROUND:Whether patient-reported symptoms and function after total knee arthroplasty (TKA) and medial unicompartmental knee arthroplasty (UKA) compare favorably to similar individuals without a diagnosis of knee pathology has not been investigated. METHODS:A retrospective, multicenter study was designed in which 4 centers contributed patients between ages 18 and 80 years undergoing knee arthroplasty. Data were collected by an independent, third-party survey center that administered a questionnaire assessing patient satisfaction and function. The survey center identified a "control" population of the same age range using a "random digit dial call method" with no prior knee interventions or major problems with their knees limiting their activity. Comparisons were performed using multivariate logistic regression analyses accounting for differences in demographic variables among the 3 cohorts. RESULTS:Overall, 1456 TKAs, 476UKAs, and 409 controls were included for analysis. Controls reported a surprisingly high incidence of pain (30%), a limp (26%), stiffness (22%), and noise (21%) in their knee. However, the likelihood of reported noise (odds ratio [OR], 1.3), swelling (OR, 1.4), stiffness (OR, 1.8), and difficulty getting in and out of a chair (OR, 2.5) was increased after TKA vs controls (P < .001-.03). The likelihood of swelling (OR, 1.8), stiffness (OR, 1.5), and difficulty getting in and out of a chair (OR, 1.7) was increased after UKA vs controls (P = .002-.005). CONCLUSION:When interviewed by an independent, third party, a substantial percentage of control patients reported the presence of knee symptoms, but to a lesser degree than patients after a knee arthroplasty. 10.1016/j.arth.2016.02.064
    The clinical outcome of minimally invasive Phase 3 Oxford unicompartmental knee arthroplasty: a 15-year follow-up of 1000 UKAs. Pandit H,Hamilton T W,Jenkins C,Mellon S J,Dodd C A F,Murray D W The bone & joint journal There have been concerns about the long-term survival of unicompartmental knee arthroplasty (UKA). This prospective study reports the 15-year survival and ten-year functional outcome of a consecutive series of 1000 minimally invasive Phase 3 Oxford medial UKAs (818 patients, 393 men, 48%, 425 women, 52%, mean age 66 years; 32 to 88). These were implanted by two surgeons involved with the design of the prosthesis to treat anteromedial osteoarthritis and spontaneous osteonecrosis of the knee, which are recommended indications. Patients were prospectively identified and followed up independently for a mean of 10.3 years (5.3 to 16.6). At ten years, the mean Oxford Knee Score was 40 (standard deviation (sd) 9; 2 to 48): 79% of knees (349) had an excellent or good outcome. There were 52 implant-related re-operations at a mean of 5.5 years (0.2 to 14.7). The most common reasons for re-operation were arthritis in the lateral compartment (2.5%, 25 knees), bearing dislocation (0.7%, seven knees) and unexplained pain (0.7%, seven knees). When all implant-related re-operations were considered as failures, the ten-year rate of survival was 94% (95% confidence interval (CI) 92 to 96) and the 15-year survival rate 91% (CI 83 to 98). When failure of the implant was the endpoint the 15-year survival was 99% (CI 96 to 100). This is the only large series of minimally invasive UKAs with 15-year survival data. The results support the continued use of minimally invasive UKA for the recommended indications. 10.1302/0301-620X.97B11.35634
    Oxford domed lateral unicompartmental knee arthroplasty. Kennedy James A,Mohammad Hasan R,Yang Irene,Mellon Stephen J,Dodd Christopher A F,Pandit Hemant G,Murray David W The bone & joint journal AIMS:To report mid- to long-term results of Oxford mobile bearing domed lateral unicompartmental knee arthroplasty (UKA), and determine the effect of potential contraindications on outcome. METHODS:A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and the presence of full-thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated. RESULTS:Median follow-up was seven years (3 to 14), and mean age at surgery was 65 years (39 to 90). Median Oxford Knee Score (OKS) was 43 (interquartile range (IQR) 37 to 47), with 260 (80%) achieving a good or excellent score (OKS > 34). Revisions occurred in 34 (10%); 14 (4%) were for dislocation, of which 12 had no recurrence following insertion of a new bearing, and 12 (4%) were revised for medial osteoarthritis (OA). Ten-year survival was 85% (95% confidence interval (CI) 79 to 90, at risk 72). Age, weight, activity, and patellofemoral erosions did not have a significant effect on the clinical outcome or survival. CONCLUSION:Domed lateral UKA provides a good alternative to total knee arthroplasty (TKA) in the management of lateral compartment OA. Although dislocation is relatively easy to treat successfully, the dislocation rate of 4% is high. It is recommended that the stability of the bearing is assessed intraoperatively. If the bearing can easily be displaced, the fixed rather than the mobile bearing version of the Oxford lateral tibial component should be inserted instead. Younger age, heavier weight, high activity, and patellofemoral erosions did not detrimentally affect outcome, so should not be considered contraindications. Cite this article: 2020;102-B(8):1033-1040. 10.1302/0301-620X.102B8.BJJ-2019-1330.R2
    Unicompartmental knee arthroplasty is effective: ten year results. Vasso Michele,Del Regno Chiara,Perisano Carlo,D'Amelio Antonio,Corona Katia,Schiavone Panni Alfredo International orthopaedics PURPOSE:Unicompartmental knee arthroplasty (UKA) presents low morbidity and complication risk and provides excellent outcomes and fast recovery. Despite these facts, knee-replacement registries have shown high failure rates for UKA, especially when compared with traditional TKA. The purpose of this study was therefore to report outcomes, complications, and ten year survivorship rate of medial ZUK unicompartmental knee prosthesis. METHODS:We retrospectively analysed 136 medial UKAs in 124 patients, with a maximum follow-up of ten years. Patients were assessed through the International Knee Society (IKS) scores and range of motion (ROM). A complete X-ray study was performed in all patients. Limb alignment was assessed by measuring the femorotibial mechanical alignment. At surgery, bone resections were performed according to proximal tibial epiphyseal axis. RESULTS:Mean IKS knee score improved from 45.7 (range 35-63) points preoperatively to 87.2 (range 71-100) points at the latest follow-up. Mean IKS function score improved from 50.9 (range 40-70) points to 89.1 (range 75-100) points (p < 0.05). Mean ROM increased from 106.1° (range 98-123°) to 128.6° (range 116-139°) (p < 0.01). Four cases (2.9 %) were revised due to failure for any cause, so that survivorship was 97.1 % at the latest follow-up. CONCLUSIONS:This study demonstrates excellent outcomes and survivorship for the ZUK unicompartmental knee prosthesis. Based on our findings, we believe that the ZUK prosthesis offers an effective and durable solution for treating medial degeneration of the knee. Level of Evidence IV - Retrospective case series study. 10.1007/s00264-015-2809-4
    Bearing design influences short- to mid-term survivorship, but not functional outcomes following lateral unicompartmental knee arthroplasty: a systematic review. Burger Joost A,Kleeblad Laura J,Sierevelt Inger N,Horstmann Wieger G,Nolte Peter A Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:To determine survivorship and functional outcomes of fixed and mobile-bearing designs in lateral unicompartmental knee arthroplasties (UKA). METHODS:Medline, EMBASE and Cochrane databases were searched. Annual revision rate and functional outcomes were assessed for both fixed and mobile-bearing designs. RESULTS:A total of 28 studies, of which 19 fixed-bearing and 9 mobile-bearing, representing 2265 lateral UKAs were included for survivorship and functional outcome analyses. The mean follow-up of fixed and mobile-bearing studies was 7.5 and 3.9 years, respectively. Annual revision rate of fixed-bearing designs was 0.94 (95% CI 0.66-1.33) compared to 2.16 (95% CI 1.54-3.04) for mobile-bearing. A subgroup analysis of the domed shaped mobile-bearing design noted an annual revision rate of 1.81 (95% CI 0.98-3.34). Good-to-excellent functional outcomes were observed following fixed and mobile-bearing lateral UKAs; no significant differences were found. CONCLUSION:Mobile-bearing lateral UKAs have a higher rate of revision compared to fixed-bearing lateral UKAs with regard to short- to mid-term survivorship; however, the clinical outcomes are similar. Despite the introduction of the domed shaped mobile-bearing design, findings of this study suggest fixed-bearing implant design is preferable in the setting of isolated lateral osteoarthritis (OA). This systematic review was based on low to moderate evidence, therefore, future registry data are needed to confirm these findings. However, this study included a large number of patients, and could provide information regarding risk of revision and functional outcomes of mobile and fixed-bearing type lateral UKA. LEVEL OF EVIDENCE:IV. 10.1007/s00167-019-05357-x
    Improved implant alignment accuracy with an accelerometer-based portable navigation system in medial unicompartmental knee arthroplasty. Suda Yoshihito,Takayama Koji,Ishida Kazunari,Hayashi Shinya,Hashimoto Shingo,Niikura Takahiro,Matsushita Takehiko,Kuroda Ryosuke,Matsumoto Tomoyuki Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:This study aimed to examine the accuracy of tibial implant alignment using an accelerometer-based portable navigation system in unicompartmental knee arthroplasty (UKA). METHODS:This retrospective matched case-control study reviewed 51 UKAs performed using an accelerometer-based portable navigation system, matched with 51 UKAs performed using conventional extramedullary rods. Coronal alignment and posterior slope of the tibial implant were measured on postoperative radiographs, and differences from preoperative planning were examined. Outliers and accuracy of tibial implant alignment were compared between the portable navigation and conventional groups using Fisher's exact test and Mann-Whitney U test, respectively. RESULTS:In the portable navigation group, 100% of the implants were aligned within 3.0° of both target coronal and sagittal implant alignment. In the conventional group, 76.5% and 88.2% of the implants were within 3.0° of both target coronal and sagittal implant alignment. Statistical analysis revealed that outliers of coronal and sagittal alignment were significantly less in the portable navigation group than in the conventional group (P < 0.05). In addition, the absolute value difference between postoperative measurement and preoperative planning of both coronal and sagittal alignment was significantly smaller in the portable navigation group than in the conventional group (P < 0.05). CONCLUSION:The portable navigation system improved the accuracy of tibial implant alignment in UKA. We found that 100% of the implants were aligned within 3.0° of both target coronal and sagittal implant alignment. The portable navigation system decreased the outliers of tibial coronal and sagittal alignment. LEVEL OF EVIDENCE:Retrospective case-control study, Level III. 10.1007/s00167-019-05669-y
    Up to twelve year follow-up of the Oxford phase three unicompartmental knee replacement in China: seven hundred and eight knees from an independent centre. Xue Huaming,Tu Yihui,Ma Tong,Wen Tao,Yang Tao,Cai Minwei International orthopaedics PURPOSE:There have been few large sample studies reporting the midterm outcome of Oxford phase 3 unicompartmental knee arthroplasty (UKA) in Asian patients. METHODS:The study included 708 consecutive medial Oxford UKAs between February 2005 and May 2014 in Chinese patients. All cases were performed for the recommended indications with a minimally-invasive surgical technique. The functional and radiological outcomes were subsequently examined. In particular, we divided patients into the spontaneous osteonecrosis of the knee (SONK) group and the osteoarthritis (OA) group. RESULTS:All patients were reviewed with a mean follow-up of 6.2 years (range 2.7-12 years). At the latest follow up, the mean Oxford knee score (OKS) increased from 22.5 to 38.5 points, while the mean knee society score (KSS) increased from 43.6 to 86.1 points. The mean visual analogue scale pain score decreased from 7.9 to 1.5 points and the mean range of motion (ROM) increased from 112.5° to 125.2°. A total of 13 UKAs (1.88%) required revisions. The most common reason was bearing dislocation and osteoarthritis of the lateral compartment. Using revision for any cause as an endpoint, the five-year cumulative survival rate was 98.8% and the ten-year survival rate was 94.3%. There was no statistically significant difference between the SONK group and the OA group for the five-year cumulative survival rate (98.7% vs. 98.8%, P > 0.05). CONCLUSION:This study demonstrates that Oxford UKA is a good option for the treatment of anteromedial OA and SONK of the knee in Asian patients. 10.1007/s00264-017-3492-4
    Does Unicompartmental Knee Replacement Offer Improved Clinical Advantages Over Total Knee Replacement in the Treatment of Isolated Lateral Osteoarthritis? A Matched Cohort Analysis From an Independent Center. Tu Yihui,Ma Tong,Wen Tao,Yang Tao,Xue Long,Xue Huaming The Journal of arthroplasty BACKGROUND:The purpose of this study is to compare the functional and radiographic results, perioperative complications, satisfaction rate, and mid-term survivorship after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) for the treatment of lateral compartmental knee osteoarthritis (LCKO). METHODS:Between March 2007 and September 2017, we identified 35 patients with primary TKAs and 121 patients with lateral UKAs (LUKAs) for LCKO with a minimum follow-up of 2 years (mean 5.3 years, range 2-12.4). The matched variables were age, gender, operation side, body mass index, American Society of Anesthesiologist grade, initial diagnosis, osteoarthritis grade in lateral compartment, and follow-up time. All patients were assessed using the Oxford Knee Score, Hospital for Special Surgery score, range of motion, length of hospital stay, satisfaction, and complications. Survivorship of UKA and TKA implants was also compared. RESULTS:At last follow-up, LUKA had a significantly better postoperative Oxford Knee Score, Hospital for Special Surgery score, range of motion, shorter length of hospital time, and higher satisfaction rate than matched TKA group. There were significant differences regarding patellar tendon injury (P = .043), superficial wound infection (P = .028), patellar snapping or impingement (P = .047), and stiffness (P < .001). Five-year survivorships free from revision were similar in both groups (99.2% vs 97.1%, P = .347). CONCLUSION:LUKA for LCKO demonstrated more favorable 5-year results in comparison with TKA. Furthermore, LUKA achieved comparable mid-term survivorship and was less likely to suffer from wound infection and knee stiffness, although not overall surgical complications. 10.1016/j.arth.2020.03.021
    Does primary or secondary chondrocalcinosis influence long-term survivorship of unicompartmental arthroplasty? Hernigou Philippe,Pascale Walter,Pascale Valerio,Homma Yasuhiro,Poignard Alexandre Clinical orthopaedics and related research BACKGROUND:Coexistence of degenerative arthritis and calcium pyrophosphate dihydrate (CPPD) crystals (or radiological chondrocalcinosis) with osteoarthritis (OA) of the knees is frequent at the time of arthroplasty. Several studies suggest more rapid clinical and radiographic progression with CPPD than with OA alone. However, it is unclear whether chondrocalcinosis predisposes to higher risks of progression of arthritis in other compartments. QUESTION/PURPOSES:We questioned whether chondrocalcinosis influences clinical scores, degeneration of other compartments, rupture of the ACL, survivorship, reason for revision, or timing of failures in case of UKA. METHODS:We retrospectively reviewed 206 patients (234 knees) who had UKAs between 1990 and 2000. Of these 234 knees, 85 had chondrocalcinosis at the time of surgery and 63 of the knees subsequently had radiographic evidence of chondrocalcinosis observed during followup. We evaluated patients with The Knee Society rating system and compared function and radiographic progression in the other compartments of patients without and with chondrocalcinosis. RESULTS:The use of conventional NSAIDs, radiographic progression of OA in the opposite femorotibial compartment of the knee, failure of the ACL, and aseptic loosening did not occur more frequently among patients with chondrocalcinosis. The 15-year cumulative survival rates were 90% and 87% for the knees without and with chondrocalcinosis, respectively, using revision to TKA as the end point. CONCLUSION:Our findings show chondrocalcinosis does not influence progression and therefore is not a contraindication to UKA. 10.1007/s11999-011-2211-5
    Bearing Dislocation and Progression of Osteoarthritis After Mobile-bearing Unicompartmental Knee Arthroplasty Vary Between Asian and Western Patients: A Meta-analysis. Ro Kyung-Han,Heo Jae-Won,Lee Dae-Hee Clinical orthopaedics and related research BACKGROUND:Implant survivorship is reported to be lower and complications, particularly bearing dislocation, are reported to be more frequent in Asian than in Western patients with medial knee osteoarthritis (OA) undergoing Oxford® Phase III unicompartmental knee arthroplasty (UKA). To date, however, these complications have not been compared between these groups of patients. QUESTIONS/PURPOSES:The purpose of this study was to perform a meta-analysis comparing the standardized incidence rates of (1) all-cause reoperation; (2) reoperation related to bearing dislocation; and (3) reoperation related to progression of lateral compartment arthritis in Asian and Western patients with medial knee OA who underwent Oxford Phase III UKA. METHODS:We searched MEDLINE® (January 1, 1976, to May 31, 2017), EMBASE® (January 1, 1985, to May 31, 2017), and the Cochrane Library (January 1, 1987, to May 31, 2017) for studies that reported complications of Oxford Phase III UKAs. Studies were included if they reported reoperation rates attributable to bearing dislocation and/or progression of lateral knee OA after surgery with this implant. Twenty-seven studies were included in this systematic review and 16 studies with followups > 5 years were included in the meta-analysis. These rates were converted to standardized incidence rate (that is, reoperations per 100 observed component years) based on mean followup and number of involved knees in each study. After applying prespecified inclusion and exclusion criteria, the studies were categorized into two groups, Asian and Western, based on hospital location. Twenty-five studies, containing 3152 Asian patients and 5455 Western patients, were evaluated. Study quality was assessed by the modified Coleman Methodology score (MCMS). Although all studies were Level IV, their mean MCMS score was 66.92 (SD, 8.7; 95% confidence interval [CI], 63.5-70.3), indicating fair quality. Because the heterogeneity of all subgroup meta-analyses was high, a random-effects model was used with estimations using the restricted maximum likelihood method. RESULTS:There was no difference in the proportion of Asian patients versus Western patients undergoing reoperation for any cause calculated as 100 component observed years (1.022 of 3152 Asian patients; 95% CI, 0.810-1.235 versus 1.300 of 5455 Western patients; 95% CI, 1.067-1.534; odds ratio, 0.7839; 95% CI, 0.5323-1.1545; p = 0.178). The mean reoperation rate attributable to bearing dislocation per 100 observed years was higher in Asian than in Western patients (0.525; 95% CI, 0.407-0.643 versus 0.141; 95% CI, 0.116-0.166; odds ratio, 3.7378; 95% CI, 1.694-8.248; p = 0.001) Conversely, the mean reoperation rate attributable to lateral knee OA per 100 observed years was lower in Asian than in Western patients (0.093; 95% CI, 0.070-0.115 versus 0.298; 95% CI, 0.217-0.379; odds ratio, 0.3114; 95% CI, 0.0986-0.9840; p < 0.001). CONCLUSIONS:Although total reoperation rates did not differ in the two populations, reoperation for bearing dislocation was more likely to occur in Asian than in Western patients, whereas reoperation for lateral knee OA progression was more likely to occur in Western than in Asian patients after Oxford Phase III UKA. Although possible explanations for these findings may be hypothesized, additional randomized, prospective comparative studies are needed. However, better survival outcomes after UKA may require consideration of ethnicity and lifestyle choices in addition to traditional surgical technique and perioperative care. LEVEL OF EVIDENCE:Level III, therapeutic study. 10.1007/s11999.0000000000000205
    Anthropometry of the medial tibial plateau in the Chinese population: the morphometric analysis and adaptability with Oxford Phase III tibial components. Lu Feifan,Zhang Qidong,Liu Pei,Guo Wanshou Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The objective of this study was to measure resected surfaces of the medial tibial plateau and to provide accurate anatomical parameters for the Chinese population and improve the unicompartmental knee arthroplasty (UKA) component design in the future. METHODS:This study measured different dimensions of the medial tibial plateau on MRIs of 1000 consecutive healthy Chinese people without knee deformity. The anteroposterior (AP) dimension and mediolateral dimensions at defined points (recorded as WA, WB, WC) of the medial tibial plateau were measured. The aspect ratio (WB/AP, recorded as AR) was also recorded. The measured results were grouped to compare with the dimensions of the Oxford Phase III tibial component. An independent t test was used to compare the differences between the males and females. RESULTS:The Oxford Phase III tibial component showed mediolateral overhang or undersize for the whole range of measured anteroposterior dimensions of the resected medial tibial plateau. A total of 71.3% patients' resected surface did not match the Oxford Phase III tibial component well. The study also found a decrease in the aspect ratio (WB/AP) with an increase in the AP dimension in the medial tibial plateau. CONCLUSIONS:There is a difference between the morphology of the Chinese knee joint and the configuration of the Oxford Phase III tibial components. The results of this study provided accurate anatomical parameters for Chinese and guidelines for designing UKA components suitable for the Chinese population. LEVEL OF EVIDENCE:Retrospective comparative study, Level III. 10.1007/s00167-019-05777-9
    Reduction in tibiofemoral conformity in lateral unicompartmental knee arthroplasty is more representative of normal knee kinematics. Koh Yong-Gon,Lee Jin-Ah,Lee Hwa-Yong,Kim Hyo-Jeong,Chung Hyun-Seok,Kang Kyoung-Tak Bone & joint research Aims:Commonly performed unicompartmental knee arthroplasty (UKA) is not designed for the lateral compartment. Additionally, the anatomical medial and lateral tibial plateaus have asymmetrical geometries, with a slightly dished medial plateau and a convex lateral plateau. Therefore, this study aims to investigate the native knee kinematics with respect to the tibial insert design corresponding to the lateral femoral component. Methods:Subject-specific finite element models were developed with tibiofemoral (TF) and patellofemoral joints for one female and four male subjects. Three different TF conformity designs were applied. Flat, convex, and conforming tibial insert designs were applied to the identical femoral component. A deep knee bend was considered as the loading condition, and the kinematic preservation in the native knee was investigated. Results:The convex design, the femoral rollback, and internal rotation were similar to those of the native knee. However, the conforming design showed a significantly decreased femoral rollback and internal rotation compared with that of the native knee (p < 0.05). The flat design showed a significant difference in the femoral rollback; however, there was no difference in the tibial internal rotation compared with that of the native knee. Conclusion:The geometry of the surface of the lateral tibial plateau determined the ability to restore the rotational kinematics of the native knee. Surgeons and implant designers should consider the geometry of the anatomical lateral tibial plateau as an important factor in the restoration of native knee kinematics after lateral UKA. 2019;8:593-600. 10.1302/2046-3758.812.BJR-2019-0114.R1
    Midterm results after unicompartmental knee replacement with all-polyethylene tibial component: a single surgeon experience. Hawi Nael,Plutat Jochen,Kendoff Daniel,Suero Eduardo M,Cross Michael B,Gehrke Thorsten,Citak Mustafa Archives of orthopaedic and trauma surgery PURPOSE:The aim of this study was to determine the survival rate, the causes of failure, and the functional outcomes of an all-polyethylene tibial unicompartmental knee prosthesis. METHODS:One hundred (100) nonselected, consecutive patients indicated for unicompartmental knee replacement for isolated medial knee compartment osteoarthritis by a single surgeon at a single institution from 2000 to 2004 were included in this study. Data was collected retrospectively at final follow-up from the hospital electronic database, including progress notes, demographic information, Hospital for Special Surgery (HSS) Knee Score, details on the surgical procedure, reoperations/revisions, and mortality. A survival analysis was performed to estimate the probability of survival over time. RESULTS:The survival probability of the all-polyethylene UKA implant was 95.4 % after a mean follow-up of 8 years, which is comparable to reports from studies using metal-backed modular designs for UKA. The causes of failure were progression of arthritis in adjacent compartments (2 %) and loosening of the tibial component (2 %). The mean preoperative HSS knee score improved from 36.6 ± 14.3 to 76.6 ± 21.6 at latest follow-up (p < 0.0001). CONCLUSIONS:In summary, an all-polyethylene tibial component has equivalent survivorship to modular designs. Implant selection does not seem to have great influence on the outcome, but rather the success depends on appropriate indications and surgical technique. 10.1007/s00402-016-2515-8
    Have the Causes of Revision for Total and Unicompartmental Knee Arthroplasties Changed During the Past Two Decades? Dyrhovden Gro S,Lygre Stein Håkon L,Badawy Mona,Gøthesen Øystein,Furnes Ove Clinical orthopaedics and related research BACKGROUND:Revisions after knee arthroplasty are expected to increase, and the epidemiology of failure mechanisms is changing as new implants, technology, and surgical techniques evolve. QUESTIONS/PURPOSES:(1) Was there improvement in survival for TKA and unicompartmental knee arthroplasty (UKA) when comparing two consecutive 11-year periods with similar followups in a national registry? (2) Were there changes in the causes of revision during the two times? (3) Could the changes in revision causes be attributed to patient or implant characteristics? METHODS:A total of 60,623 TKAs (2426 revisions) and 7648 UKAs (725 revisions) were selected from the Norwegian Arthroplasty Register and analyzed based on year of primary surgery: 1994 to 2004 (Period 1) and 2005 to 2015 (Period 2). TKAs had median followup of 3.5 years in Period 1 and 4.2 years in Period 2. Median followup for UKAs was 2.7 years in Period 1 and 4.6 years in Period 2. Of the patients included in the registry, 99.6% were accounted for at the time of analysis, whereas 0.4% had moved abroad. We used Kaplan-Meier analyses and log-rank test to investigate changes in survival. Relative risk of revision in Period 2 relative to Period 1 was calculated for each registered revision cause in a Cox regression model adjusted for age, sex, diagnosis, fixation, and patella resurfacing. RESULTS:For TKAs, the 10-year Kaplan-Meier survival free from revision improved from Period 1 to Period 2 from 91% (95% CI, 90%-92%) to 94% (95% CI, 94%-95%; p < 0.001). Revisions resulting from aseptic loosening of the femoral component, polyethylene wear/breakage, patellar dislocation, and unexplained pain decreased, whereas revisions resulting from early infection increased. Patients in Period 2 were younger and more often men compared with patients in Period 1. A higher risk of revision was found for male sex (relative risk [RR], 1.1; 95% CI, 1.0-1.2; p = 0.048) and age younger than 65 years (RR, 1.7; 95% CI, 1.6-1.9; p < 0.001). With UKAs, the 10-year survival free from revision was 80% (95% CI, 76%-84%) in Period 1 and 81% (95% CI, 79%-83%; p = 0.261) in Period 2. Revisions resulting from tibial aseptic loosening, polyethylene wear/breakage, and periprosthetic fractures decreased, but there were more revisions resulting from progression of osteoarthritis. In Period 2, there were more men and the average age was younger than for patients in Period 1. For UKAs, age younger than 65 years had a higher risk of revision (RR, 1.7; 95% CI, 1.5-2.0; p < 0.001), whereas sex did not affect the risk of revision. CONCLUSIONS:We found an improvement in survival free from revision for TKA in the last period, but no similar improvement for UKA, and the survivorship for UKAs remains rather dramatically lower than that observed for TKAs. The decision to perform a UKA should be made with the explicit awareness that its survivorship is substantially inferior to that of TKA; any perceived advantages of UKA should be balanced against this issue of its decreased durability. LEVEL OF EVIDENCE:Level III, therapeutic study. 10.1007/s11999-017-5316-7
    Navigation of the tibial plateau alone appears to be sufficient in computer-assisted unicompartmental knee arthroplasty. Saragaglia Dominique,Picard Frédéric,Refaie Ramsay International orthopaedics PURPOSE:The aim of this study was to present our technique to implant unicompartmental knee arthroplasty (UKA) using navigation and to give our first results regarding the accuracy of the device. METHODS:A total of 33 patients with medial femorotibial osteoarthritis (31) or avascular necrosis (2) were included in this study. The mean preoperative hip-knee-ankle (HKA) angle was 172.7 ± 2.2° (range 167-177°) and the preoperative planning aimed to reach an HKA angle between 175 and 179° (177 ± 2°), a tibial varus at 3 ± 1°, which means a tibial mechanical angle (TMA) close to 87 ± 1°, and posterior tibial slope at 3 ± 2°. In all cases, we used the OrthoPilot® device with dedicated software allowing us to navigate only the tibial plateau. RESULTS:The preoperative plan was reached in 93.9 % of cases for HKA angle, 84.8 % for TMA and 100 % for the posterior slope. CONCLUSIONS:Unicompartmental knee navigation is reliable. The navigation of only the tibial bone cut is a reasonable option as has been shown in this study. Its role is invaluable in the positioning of mobile-bearing UKA, where the risk of overcorrection should not be underestimated. 10.1007/s00264-012-1679-2
    The influence of obesity on clinical outcomes of fixed-bearing unicompartmental knee arthroplasty: a ten-year follow-up study. Xu S,Lim W-A J,Chen J Y,Lo N N,Chia S-L,Tay D K J,Hao Y,Yeo S J The bone & joint journal AIMS:The aim of this study was to assess the influence of obesity on the clinical outcomes and survivorship ten years postoperatively in patients who underwent a fixed-bearing unicompartmental knee arthroplasty (UKA). PATIENTS AND METHODS:We prospectively followed 184 patients who underwent UKA between 2003 and 2007 for a minimum of ten years. A total of 142 patients with preoperative body mass index (BMI) of < 30 kg/m were in the control group (32 male, 110 female) and 42 patients with BMI of ≥ 30 kg/m were in the obese group (five male, 37 female). Pre- and postoperative range of movement (ROM), Knee Society Score (KSS), Oxford Knee Score (OKS), 36-Item Short-Form Health Survey (SF-36), and survivorship were analyzed. RESULTS:Patients in the obese group underwent UKA at a significantly younger mean age (56.5 years (sd 6.4)) than those in the control group (62.4 years (sd 7.8); p < 0.001). There was no significant difference in preoperative functional scores. However, those in the obese group had a significantly lower ROM (116° (sd 15°) vs 123° (sd 17°); p = 0.003). Both groups achieved significant improvement in outcome scores regardless of BMI, ten years postoperatively. All patients achieved the minimal clinically important difference (MCID) for OKS and KSS. Both groups also had high rates of satisfaction (96.3% in the control group and 97.5% in the obese group) and the fulfilment of expectations (94.9% in the control group and 95.0% in the obese group). Multiple linear regression showed a clear association between obesity and a lower OKS two years postoperatively and Knee Society Function Score (KSFS) ten years postoperatively. After applying propensity matching, obese patients had a significantly lower KSFS, OKS, and physical component score (PCS) ten years postoperatively. Seven patients underwent revision to total knee arthroplasty (TKA), two in the control group and five in the obese group, resulting in a mean rate of survival at ten years of 98.6% and 88.1%, respectively (p = 0.012). CONCLUSION:Both groups had significant improvements in functional and quality-of-life scores postoperatively. However, obesity was a significant predictor of poorer improvement in clinical outcome and an increased rate of revision ten years postoperatively. 10.1302/0301-620X.101B2.BJJ-2018-0969.R2
    Alteration in skin sensation following knee arthroplasty and its impact on kneeling ability: a comparison of three common surgical incisions. Hassaballa Mo,Artz Neil,Weale Adrian,Porteous Andrew Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Disturbance in skin sensation is a recognised, often unpleasant consequence of knee replacement for many patients and may affect function especially kneeling. The aim of this study was to compare post-operative changes in skin sensation following total (TKA) and unicompartmental knee (UKA) arthroplasties using three different incision types and its effect on kneeling ability. METHODS:Skin sensation was recorded using a purpose-designed grid over the front of the knee in 72 patients (78 knees) following knee arthroplasty. Surface area of sensory change, length of incision, and kneeling ability were recorded and compared between three different types of incision; long antero-medial and midline for TKA, and short medial for UKA. RESULTS:The average length of the long antero-medial incision was 19 ± 5 cm with an average area of sensory alteration of 88 ± 56 cm(2). The average length of the midline incision was 18 ± 3 cm with an average area of sensory alteration of 57 ± 52 cm(2). The short medial incision used for UKA averaged 11 ± 3 cm in length with an average area of sensory alteration of 54 ± 45 cm(2). Long antero-medial produced a significantly greater area of sensory alteration than standard short medial (P = 0.017), but not the midline incision. There was a significant positive correlation of incision length with reduced sensation. Patients unable to kneel demonstrated a significantly larger area of hypersensitivity than patients who could kneel (P = 0.002). CONCLUSIONS:Increased length of incision results in a greater surface area of sensory change in the front of the knee. This finding was greatest in the long antero-medial incisions used in TKA. The inability to kneel following knee arthroplasty is associated with increased area of hypersensitivity of the anterior knee. LEVEL OF EVIDENCE:Prospective comparative study, Level II. 10.1007/s00167-011-1727-2
    Flexion and extension laxity after medial, mobile-bearing unicompartmental knee arthroplasty: a comparison between a spacer- and a tension-guided technique. ten Ham A M,Heesterbeek P J C,van der Schaaf D B,Jacobs W C H,Wymenga A B Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:In a mobile-bearing unicompartmental knee arthroplasty (UKA), stability is of utmost importance to promote knee function and to prevent dislocation of the insert. Gap balancing can be guided by the use of spacers or a tensioner. The goal of this study is to compare laxity of a tension-guided implantation technique versus a spacer-guided technique for medial UKA with a mobile bearing. Also clinical function was compared between the groups. METHODS:The tension-guided UKA system (BalanSys™, Mathys Ltd, Bettlach, Switzerland) was compared with a retrospective group with a spacer-guided system (Oxford, Biomet Ltd, Bridgend, UK). A total of 30 tension-guided medial UKAs were implanted and compared with 35 spacer-guided medial prostheses. In both groups, valgus laxity was measured at least 4 months postoperatively in extension and 70° flexion using stress radiographs. Knee Society Scores (KSS) were obtained at the 6-month follow-up. RESULTS:Valgus laxity in flexion was significantly higher in the tension-guided group compared with the spacer-guided group: 3.9° (SD 1.8°) versus 2.4° (SD 1.2°), respectively, P < 0.001). In extension, valgus laxity was significantly different: 1.8° (SD 1.0°) in the tension-guided group compared with 2.7° (SD 0.9°) in the spacer-guided group (P < 0.001). There was no significant difference between the KSS for the two groups (n.s.). CONCLUSIONS:The tensor-guided system resulted in significantly more valgus laxity in flexion compared with the spacer-guided system. However, in extension, the situation was reversed: the tension-guided system resulted in less valgus laxity than the spacer-guided system. Clinically, there were no differences between the groups. The valgus laxity found with the spacer-guided system better approximates the valgus laxity values of the healthy elderly. 10.1007/s00167-012-2021-7
    Robotic arm-assisted conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. Blyth M J G,Anthony I,Rowe P,Banger M S,MacLean A,Jones B Bone & joint research OBJECTIVES:This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group. METHODS:A total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery. RESULTS:From the first post-operative day through to week 8 post-operatively, the median pain scores for the robotic arm-assisted group were 55.4% lower than those observed in the manual surgery group (p = 0.040).At three months post-operatively, the robotic arm-assisted group had better AKSS (robotic median 164, interquartile range (IQR) 131 to 178, manual median 143, IQR 132 to 166), although no difference was noted with the OKS.At one year post-operatively, the observed differences with the AKSS had narrowed from a median of 21 points to a median of seven points (p = 0.106) (robotic median 171, IQR 153 to 179; manual median 164, IQR 144 to 182). No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43). A greater proportion of patients receiving robotic arm-assisted surgery improved their UCLA activity score.Binary logistic regression modelling for dichotomised outcome scores predicted the key factors associated with achieving excellent outcome on the AKSS: a pre-operative activity level > 5 on the UCLA activity score and use of robotic-arm surgery. For the same regression modelling, factors associated with a poor outcome were manual surgery and pre-operative depression. CONCLUSION:Robotic arm-assisted surgery results in improved early pain scores and early function scores in some patient-reported outcomes measures, but no difference was observed at one year post-operatively. Although improved results favoured the robotic arm-assisted group in active patients (i.e. UCLA ⩾ 5), these do not withstand adjustment for multiple comparisons.: M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. MacLean, B. Jones. Robotic arm-assisted conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. 2017;6:631-639. DOI: 10.1302/2046-3758.611.BJR-2017-0060.R1. 10.1302/2046-3758.611.BJR-2017-0060.R1
    Midterm-Adjusted Survival Comparing the Best Performing Unicompartmental and Total Knee Arthroplasties in a Registry. Bini Stefano A,Cafri Guy,Khatod Monti The Journal of arthroplasty BACKGROUND:Recent literature suggests that the difference in revision risk between unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) can be influenced by surgeon volume and other confounders. We hypothesized that implant selection might decrease the relative risk of revision in an adjusted model. METHODS:We selected the best performing (BP) primary UKAs and TKAs performed for osteoarthritis between January 2001 and December 2012 collected through a joint replacement registry. We compared aseptic and all-cause risk of revision using a surgeon-stratified Cox regression model with propensity score adjustment. RESULTS:One thousand fifty-four UKAs were compared with 74,185 TKAs. The rate for all-cause revision was lower for UKAs (2.1%) than for TKAs (2.4%), whereas the rate for aseptic revision was higher for UKAs (2.0%) than TKAs (1.4%). The adjusted risk of aseptic revision was not significantly higher for UKA than TKA (hazard ratio = 2.02 [0.68, 5.96], P = .203) or all-cause revision (hazard ratio = 1.24 [0.52, 2.98], P = .603). CONCLUSION:When comparing the survivorship of the BP UKAs to the BP TKAs in our registry, the adjusted risk of revision remained higher for UKAs than for TKAs, although the difference did not reach statistical significance. 10.1016/j.arth.2017.05.050
    Improved accuracy in computer-assisted unicondylar knee arthroplasty: a meta-analysis. Weber Patrick,Crispin Alexander,Schmidutz Florian,Utzschneider Sandra,Pietschmann Matthias F,Jansson Volkmar,Müller Peter E Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Inaccurate implantation rates of up to 30 % have been reported in cases using the conventional technique for implantation of a unicompartmental knee arthroplasty. Navigation should permit a more precise implantation, and several studies have investigated its role, albeit with a limited number of patients and inconsistent results. The aim of this meta-analysis was to compare risks of unsatisfactory outcomes in patients with navigated and conventional technique. METHODS:An electronic search was performed, and ten studies were eligible and included in the meta-analysis, with a total of 258 prostheses implanted with the navigated technique and 295 with the conventional one. The following items were analysed: radiological positioning of the femoral and the tibial component in the AP and lateral view, radiological analysis of the tibiofemoral mechanical axis and the difference in operating time between the two groups. Relative risks (RR) were calculated from the reported percentages of implants outside the optimal ranges defined by the manufacturers or the study groups. Natural logarithms of the relative risks were pooled by means of random effects models. RESULTS:For all the analysed radiological parameters, the RR of measurements outside the optimal ranges were less than 1 in the navigation group suggesting a reduction in the risk of outliers with navigation. The average operating time in the navigated group was 15.4 min (95 % CI: 10.2-20.6) longer than in the conventional group. CONCLUSION:The meta-analysis shows that the use of navigation systems in UKA leads to a more precise component position. Whether the more accurate position in UKA results in a better clinical outcome or long-term survival is yet unknown. Nevertheless, as a precise implant position appears to be beneficial, the use of navigation should be recommended for UKA. The limits defined by the manufacturers for an optimal positioning are not consistent. 10.1007/s00167-013-2370-x
    Outpatient surgery for unicompartmental knee arthroplasty is effective and safe. Kort Nanne P,Bemelmans Yoeri F L,Schotanus Martijn G M Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:There has been increasing interest in accelerated programs for knee arthroplasty. We examined the efficacy and safety of an outpatient surgery (OS) pathway in patients undergoing unicompartmental knee arthroplasty (UKA). METHODS:This case-controlled study evaluates patients operated for UKA in an OS pathway (n = 20) compared to rapid recovery (RR), the current standard (n = 20). We investigated whether patients could be discharged on the day of surgery, resulting in comparable or better outcome by means of adverse events (AEs) in terms of pain (numerical rating scale, NRS), incidences of postoperative nausea and vomiting (PONV) and opiate use (<48 h postoperatively), complication and readmission rates (<3 months postoperatively). Patient-reported outcome measures (PROMS) were obtained preoperatively and 3 months postoperatively. RESULTS:Postoperative pain (NRS > 5) was the most common reason for prolonged hospital stay in the OS pathway. Eighty-five per cent of the patients were discharged on the day of surgery, whereas 95 % of the patients were discharged on postoperative day 3 in the RR pathway. Overall, median pain scores in both pathways did not exceed a NRS score of 5, without significant differences (RR vs. OS) in the number of patients with PONV (4 vs. 2) and opiate use (11 vs. 9) <48 h postoperatively. At 3 months postoperatively, no significant differences were found for AEs and PROMS between both pathways. CONCLUSION:The results of this study illustrates that an OS pathway for UKA is effective and safe with acceptable clinical outcome. Well-established and adequate standardized protocols, inclusion and exclusion criteria and a change in mindset for both the patient and the multidisciplinary team are the key factors for the implementation of an OS pathway. LEVEL OF EVIDENCE:Case-control study, Level III. 10.1007/s00167-015-3680-y
    Unicondylar arthroplasty in knees with deficient anterior cruciate ligaments. Engh Gerard A,Ammeen Deborah J Clinical orthopaedics and related research BACKGROUND:Historically, a functional ACL has been a prerequisite for patients undergoing unicondylar knee arthroplasty (UKA). However, this premise has not been rigorously tested. QUESTIONS/PURPOSES:We compared (1) the survivorship free from revision and (2) the failure mechanisms of UKAs in ACL-deficient knees and UKAs in ACL-intact knees performed over the same time interval. METHODS:Between November 2000 and July 2008, a fixed bearing UKA was performed in 72 patients (81 knees) with intraoperatively confirmed ACL deficiency. Five patients (five knees) with preoperative instability underwent ACL reconstruction and were excluded from analysis. Of the remaining 67 patients (76 knees) without preoperative instability, implant status was known for 68 UKAs in 60 patients. Survivorship and failure mechanisms for these knees were compared to those of 706 UKAs in ACL-intact knees performed during the same time interval by the same surgeon using the same implant system. Minimum followup for the ACL-deficient group was 2.9 years (mean, 6 years; range, 2.9-10 years). RESULTS:Revision rates between UKAs with and without intact ACLs were similar in the absence of clinical instability (p = 0.58). Six-year UKA survivorship was 94% (95% CI: 88%-100%) in ACL-deficient knees and 93% (95% CI: 91%-96%) in ACL-intact knees (p = 0.89). Five knees (7%) in the ACL-deficient group were revised: disease progression (two), loose tibia (one), persistent pain (one), and revised elsewhere/reason unknown (one). Thirty-six knees in the ACL-intact group underwent revision (5%): aseptic loosening (13), revised elsewhere/reason unknown (11), disease progression (three), tibial subsidence/fracture (four), infection (three), pain (one), and lateral compartment overload (one). CONCLUSIONS:At 6 years, deficiency of the ACL in patients without clinical knee instability did not impact the survivorship of UKAs compared to UKAs performed in knees with intact ACLs. 10.1007/s11999-013-2982-y
    Initial experience with the oxford unicompartmental knee arthroplasty. Dervin Geoffrey F,Carruthers Chris,Feibel Robert J,Giachino Alan A,Kim Paul R,Thurston Peter R The Journal of arthroplasty Our initial experience with mobile bearing medial compartment unicompartmental arthroplasty (UKA) is presented to highlight lessons that have been learned to avoid short-term failures. Consecutive cases of the Oxford medial UKA performed between February 2001 and April 2006 were reviewed to derive those cases that were revised to total knee arthroplasty (TKA). There were 545 patients available with mean age and body mass index of 65.0 and 30.1, respectively. At final follow-up, 32 patients were revised for lateral compartment arthritis, aseptic component loosening, persisting medial or anterior pain and dislocated meniscal bearing. Revisions were performed with primary unconstrained TKA implants with no stems or wedges required. Our results seem to reflect those seen in registries confirming an earlier higher revision rate and highlight the technical issues of overstuffing the compartment, inadequate cementation technique, and strict adherence to patient selection. 10.1016/j.arth.2010.02.007
    Outcomes of unicompartmental knee arthroplasty stratified by body mass index. Bonutti Peter M,Goddard Maria S,Zywiel Michael G,Khanuja Harpal S,Johnson Aaron J,Mont Michael A The Journal of arthroplasty Patients who have high body mass indices can have disabling medial compartment knee osteoarthritis, which might benefit from unicompartmental knee arthroplasty (UKA). The purpose of this study was to compare clinical and radiographic outcomes of UKAs in patients with body mass indices (BMIs) greater and less than 35 kg/m(2). Thirty-four patients (40 knees) had BMIs of 35 kg/m(2) or greater, whereas the remaining 33 patients (40 knees) had BMIs below 35 kg/m(2), with 2-year minimum follow-up. In the high-BMI group, 5 knees were revised to total knee arthroplasty, compared with none in the lower BMI group. Knee Society scores were lower in the surviving high-BMI knees. All surviving components were radiographically stable. The results suggest that UKA should be approached with caution in patients who have high BMIs. 10.1016/j.arth.2010.11.001
    Tibial component alignment and risk of loosening in unicompartmental knee arthroplasty: a radiographic and radiostereometric study. Barbadoro P,Ensini A,Leardini A,d'Amato M,Feliciangeli A,Timoncini A,Amadei F,Belvedere C,Giannini S Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Unicompartmental knee arthroplasty (UKA) has shown a higher rate of revision compared with total knee arthroplasty. The success of UKA depends on prosthesis component alignment, fixation and soft tissue integrity. The tibial cut is the crucial surgical step. The hypothesis of the present study is that tibial component malalignment is correlated with its risk of loosening in UKA. METHODS:This study was performed in twenty-three patients undergoing primary cemented unicompartmental knee arthroplasties. Translations and rotations of the tibial component and the maximum total point motion (MTPM) were measured using radiostereometric analysis at 3, 6, 12 and 24 months. Standard radiological evaluations were also performed immediately before and after surgery. Varus/valgus and posterior slope of the tibial component and tibial-femoral axes were correlated with radiostereometric micro-motion. A survival analysis was also performed at an average of 5.9 years by contacting patients by phone. RESULTS:Varus alignment of the tibial component was significantly correlated with MTPM, anterior tibial sinking, varus rotation and anterior and medial translations from radiostereometry. The posterior slope of the tibial component was correlated with external rotation. The survival rate at an average of 5.9 years was 89%. The two patients who underwent revision presented a tibial component varus angle of 10° for both. CONCLUSIONS:There is correlation between varus orientation of the tibial component and MTPM from radiostereometry in unicompartmental knee arthroplasties. Particularly, a misalignment in varus larger than 5° could lead to risk of loosening the tibial component. LEVEL OF EVIDENCE:Prognostic studies-retrospective study, Level II. 10.1007/s00167-014-3147-6
    Is isolated insert exchange a valuable choice for polyethylene wear in metal-backed unicompartmental knee arthroplasty? Lunebourg Alexandre,Parratte Sébastien,Galland Alexandre,Lecuire François,Ollivier Matthieu,Argenson Jean-Noël Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The aim of this study was to evaluate the clinical outcome and survival rate after isolated liner exchange for polyethylene (PE) wear in well-fixed metal-backed fixed-bearing unicompartmental knee arthroplasty (UKA). METHODS:Twenty medial UKAs in 19 patients [mean age 68.7 years ± 8.7 (range 48.5-81.5 years)] operated on for a direct PE liner exchange after isolated PE wear between 1996 and 2010 in two institutions were retrospectively reviewed. The mean delay between the index operation and revision was 8.2 years ± 2.6 (range 4.8-12.8 years). A four-level satisfaction questionnaire was used, and clinical outcomes were assessed using Knee Society scores (KSS) and range of motion (ROM) evaluation. Radiological evaluation analysed the position of the implants and progression of the disease. Survival rate of the implants was evaluated using Kaplan-Meier analysis with two different end-points. RESULTS:At the last follow-up [mean 6.8 years ± 5.2 (range 1.1-15.9 years)], 15 patients (79 %) were enthusiastic or satisfied. KSS improved from 73.4 to 86.4 points (p = 0.01) and function from 58.9 to 89.2 points (p < 0.001). ROM at last FU was 126.5° ± 10.3°. The survival rate at 12 years considering "revision for any reason" as the end-point was 71.3 ± 15.3 %, and the survival rate at 12 years considering "revision of UKA to TKA" as the end-point was 93.3 ± 6.4 %. CONCLUSION:Isolated liner exchange for PE wear in well-fixed metal-backed fixed-bearing UKA represents a valuable treatment option in selective patients with durable improvement of clinical outcomes without compromising any future revision. LEVEL OF EVIDENCE:Retrospective therapeutic study, Level IV. 10.1007/s00167-014-3392-8
    The tibia first technique with tensor measurement is useful to predict the soft tissue tension after implantation in unicompartmental knee arthroplasty. Takayama Koji,Matsumoto Tomoyuki,Muratsu Hirotsugu,Ishida Kazunari,Shibanuma Nao,Araki Daisuke,Matsushita Takehiko,Kuroda Ryosuke,Kurosaka Masahiro International orthopaedics PURPOSE:The tibia first technique in unicompartmental knee arthroplasty (UKA) may have the advantage that surgeons can obtain a balanced flexion-extension gap. However, changes of the soft tissue tension during UKA have not been elucidated yet. The purpose of this study was to examine the correlation between the soft tissue tension before the femoral osteotomy and after the femoral component is in place using the tibia first technique in UKA. METHODS:Thirty UKAs for isolated medial compartmental osteoarthritis or idiopathic osteonecrosis were assessed. The actual values of the proximal and posterior femoral osteotomy were calculated by adding the thickness of the bone saw blades to the thickness of the bony cut. Using a UKA tensor designed to facilitate intra-operative soft tissue tension throughout the range of motion (ROM), the original gap before the femoral osteotomy, the component gap after the femoral osteotomy, and component placement were assessed under 20-lb distraction forces. RESULTS:The mean actual thickness of the distal femoral osteotomy was 6.5 ± 1.3 mm and the posterior femoral osteotomy was 7.4 ± 1.3 mm. The distal thickness of the prosthesis was set to 6.5 mm and the mean posterior thickness of the prosthesis used in this study was 5.8 ± 0.3 mm. There is a positive correlation between the original and component gap throughout the ROM (R > 0.5). The original and component gap showed the same kinematic pattern from full extension to 90° of knee flexion. However, the component gap was significantly higher compared to the original gap after 120° of knee flexion (P < 0.001). CONCLUSIONS:Despite the fact that the component gap values were significantly higher compared to the original gap value in deep flexion, there is a positive correlation between the original and component gap throughout the ROM. The discrepancy during deep flexion was due to the posterior design of the prosthesis that is designed to be thinner than the actual thickness of the posterior osteotomy. These results suggest that the tibia first technique with the tensor have the advantage that surgeons can predict final soft tissue tension before femoral osteotomies with the prosthetic design and help restore natural knee kinematics, potentially improving implant survival and functional outcomes. 10.1007/s00264-014-2531-7
    Evaluating Patients' Expectations From a Novel Patient-Centered Perspective Predicts Knee Arthroplasty Outcome. Filbay Stephanie R,Judge Andrew,Delmestri Antonella,Arden Nigel K, The Journal of arthroplasty BACKGROUND:One-in-five patients are dissatisfied following knee arthroplasty and <50% have fulfilled expectations. The relationship between knee-arthroplasty expectations and surgical outcome remains unclear. PURPOSE:Are expectations regarding the impact of pain on postoperative life predictive of one-year outcome? Does the impact of pain on preoperative quality of life (QOL) influence this relationship? METHODS:Longitudinal cohort of 1044 uni-compartmental (43%) or total knee-arthroplasty (57%) (UKA or TKA) patients, aged mean 69 ± 9 years. Preoperatively, patients reported the impact of pain on QOL and expected impact of pain on life one-year post-arthroplasty. One-year postoperative outcomes: non-return to desired activity, surgical dissatisfaction, not achieving Oxford Knee Score minimal important change (OKS <MIC). Logistic regression including covariates was performed for all patients and subgroups (better vs worse pre-operative pain-related QOL; UKA vs TKA). RESULTS:Expecting moderate-to-extreme pain (vs no pain) predicted non-return to activity (odds ratio [95% confidence interval], 2.3 [1.3, 4.1]), dissatisfaction (4.0 [1.7, 9.3]), OKS <MIC (3.1 [1.5, 6.3]). Expecting mild pain (vs no pain) predicted worse outcomes for patients with better preoperative pain-related QOL (non-return to activity: 2.7 [1.5, 4.8], OKS <MIC: 2.5 [1.1, 5.5]). Expecting moderate-to-extreme pain (vs. no pain) predicted worse outcomes for patients with worse preoperative pain-related QOL (non-return to activity: 2.4 [1.1, 5.5], dissatisfaction: 5.0 [1.7, 14.8], OKS <MIC: 3.4 [1.4, 8.6]). The odds of a poor outcome in people with worse expectations was higher for UKA patients. CONCLUSIONS:Expecting a worse outcome predicted surgical dissatisfaction, less clinical improvement and non-return to desired activity. Patients expecting a more optimistic outcome relative to preoperative status achieved better surgical outcomes. 10.1016/j.arth.2018.02.026
    How should we evaluate robotics in the operating theatre? Vermue Hannes,Lambrechts Jasper,Tampere Thomas,Arnout Nele,Auvinet Edouard,Victor Jan The bone & joint journal The application of robotics in the operating theatre for knee arthroplasty remains controversial. As with all new technology, the introduction of new systems might be associated with a learning curve. However, guidelines on how to assess the introduction of robotics in the operating theatre are lacking. This systematic review aims to evaluate the current evidence on the learning curve of robot-assisted knee arthroplasty. An extensive literature search of PubMed, Medline, Embase, Web of Science, and Cochrane Library was conducted. Randomized controlled trials, comparative studies, and cohort studies were included. Outcomes assessed included: time required for surgery, stress levels of the surgical team, complications in regard to surgical experience level or time needed for surgery, size prediction of preoperative templating, and alignment according to the number of knee arthroplasties performed. A total of 11 studies met the inclusion criteria. Most were of medium to low quality. The operating time of robot-assisted total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) is associated with a learning curve of between six to 20 cases and six to 36 cases respectively. Surgical team stress levels show a learning curve of seven cases in TKA and six cases for UKA. Experience with the robotic systems did not influence implant positioning, preoperative planning, and postoperative complications. Robot-assisted TKA and UKA is associated with a learning curve regarding operating time and surgical team stress levels. Future evaluation of robotics in the operating theatre should include detailed measurement of the various aspects of the total operating time, including total robotic time and time needed for preoperative planning. The prior experience of the surgical team should also be evaluated and reported. Cite this article: 2020;102-B(4):407-413. 10.1302/0301-620X.102B4.BJJ-2019-1210.R1
    Unicompartmental knee arthroplasty survivorship is lower than TKA survivorship: a 27-year Finnish registry study. Niinimäki Tuukka,Eskelinen Antti,Mäkelä Keijo,Ohtonen Pasi,Puhto Ari-Pekka,Remes Ville Clinical orthopaedics and related research BACKGROUND:Balancing the relative advantages and disadvantages of unicompartmental knee arthroplasties (UKAs) against those for TKAs can be challenging. Survivorship is one important end point; arthroplasty registers repeatedly report inferior midterm survival rates, but longer-term data are sparse. Comparing survival directly by using arthroplasty register survival reports also may be inadequate because of differences in indications, implant designs, and patient demographics in patients having UKAs and TKAs. QUESTIONS/PURPOSES:The aims of this study were to assess the survivorship of UKA in the context of one large, northern European registry, and to compare the rates of survivorship with those of cemented TKAs performed for primary knee osteoarthritis during the same 27-year period. METHODS:From the Finnish Arthroplasty Register, we obtained the data for 4713 patients undergoing UKAs for primary osteoarthritis (mean age, 63.5 years; minimum followup, 0 years; mean, 6.0 years; range, 0-24 years) who had surgical revision between 1985 and 2011. From this cohort, we calculated the Kaplan-Meier survivorship for revision performed for any reason and compared it with the survivorship of 83,511 patients (mean age, 69.5 years; minimum followup 0 years; mean, 6.4 years; range, 0-27 years) with TKAs treated for primary osteoarthritis during the same period. Data were adjusted for age and sex in a comparative analysis. RESULTS:Kaplan-Meier survivorship of UKAs was 89.4% at 5 years, 80.6% at 10 years, and 69.6% at 15 years; the corresponding rates for TKAs were 96.3%, 93.3%, and 88.7%, respectively. UKAs had inferior long-term survivorship compared with cemented TKAs, even after adjusting for the age and sex of the patients (hazard ratio 2.2, p < 0.001). CONCLUSIONS:A UKA offers tempting advantages compared with a TKA; however, the revision frequency for UKAs in widespread use, as measured in a large, national registry, was poorer than that of TKAs. When choosing between a UKA and a TKA, patients should be informed of advantages of both procedures, but they also should be advised about the generally higher revision risk after UKA. LEVEL OF EVIDENCE:Level III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence. 10.1007/s11999-013-3347-2
    Does Unicondylar Knee Arthroplasty Affect Tibial Bone Strain? A Paired Cadaveric Comparison of Fixed- and Mobile-bearing Designs. Peersman Geert,Taylan Orcun,Slane Joshua,Vanthienen Ben,Verhaegen Jeroen,Anthonissen Lyne,van Lenthe G Harry,Heyse Thomas,Scheys Lennart Clinical orthopaedics and related research BACKGROUND:Unexplained pain in the medial proximal tibia frequently leads to revision after unicondylar knee arthroplasty (UKA). As one of the most important factors for osteogenic adaptive response, increased bone strain following UKA has been suggested as a possible cause. QUESTIONS/PURPOSES:In this study we: (1) performed a cadaver-based kinematic analysis on paired cadaveric specimens before and after mobile-bearing and fixed-bearing UKA; and (2) simultaneously characterized the strain distribution in the anterior and posterior proximal tibia during squatting. METHODS:Five pairs of fresh, frozen full-leg cadaver specimens (four male, one female, 64 years to 87 years) were subjected to a dynamic squatting motion on a kinematic rig to simulate joint loading for a large ROM. Forces were applied to the quadriceps and hamstrings during the simulation while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Tibial cortical bone strain was measured with stacked strain gauge rosettes attached at predefined anterior and posterior positions on the medial cortex. Pairwise implantation of mobile-bearing (UKAMB) and fixed-bearing implants (UKAFB) allowed a direct comparison of right and left knees from the same donor through a linear mixed model. RESULTS:UKAMB more closely replicated native kinematics in terms of tibial rotation and in AP and mediolateral translation. Maximum principal bone strain values were consistently increased compared with native (anteromedial, mean [± SD] peak strain: 311 µε ± 190 and posterior, mean peak strain: 321 µε ± 147) with both designs in the anteromedial (UKAFB, mean peak strain: 551 µε ± 381, Cohen's d effect size 1.3 and UKAMB, mean peak strain: 596 µε ± 564, Cohen's d effect size 1.5) and posterior (UKAFB, mean peak strain: 505 µε ± 511, Cohen's d effect size 1.3 and UKAMB, mean peak strain: 633 µε ± 424, Cohen's d effect size 2.1) region. However, in the anterolateral region of the medial tibial bone, UKAFB demonstrated the overall largest increase in strain (mean peak strain: 1010 µε ± 787, Cohen's d effect size 1.9), while UKAMB (613 µε ± 395, Cohen's d effect size 0.2) closely replicated values of the native knee (563 µε ± 234). CONCLUSION:In this in vitro cadaver study both UKAMB and UKAFB led to an increase in bone strain in comparison with the native knee. However, in the anterolateral region of the medial tibial plateau, proximal tibial bone strain was lower after UKAMB and UKAFB. Both UKAMB and UKAFB lead to comparable increases in anteromedial and posterior tibial strain in comparison with the native knee. In the anterolateral region of the medial tibial plateau UKA, proximal tibial bone strain was closer to the native knee after UKAMB than after UKAFB. In an attempt to link kinematics and strain behavior of these designs there seemed to be no obvious relation. CLINICAL RELEVANCE:Further clinical research may be able to discern whether the observed differences in cortical strain after UKA is associated with unexplained pain in patients and whether the observed differences in cortical bone strain between mobile-bearing and fixed unicondylar designs results in a further difference in unexplained pain. 10.1097/CORR.0000000000001169
    High Survival Rate and Very Low Wear of Lateral Unicompartmental Arthroplasty at Long Term: A Case Series of 54 Cases at a Mean Follow-Up of 17 Years. Deroche Etienne,Batailler Cécile,Lording Timothy,Neyret Philippe,Servien Elvire,Lustig Sébastien The Journal of arthroplasty BACKGROUND:Survivorship of lateral unicompartmental knee arthroplasty (UKA) has progressively improved. However, there are few studies describing long-term results, and no study reports on polyethylene (PE) wear in lateral unicompartmental arthroplasty. The aims of this study are to determine the survival rate of lateral UKA with a fixed, all-PE bearing, and the PE wear of the tibial implant at a minimum of 15 years follow-up. METHODS:From January 1988 to October 2003, we performed 54 lateral UKAs in 52 patients. All patients had isolated lateral osteoarthritis (OA). The mean age at the index procedure was 65.4 ± 11 years. Thirty-nine UKAs were available for follow-up (30 alive and 9 dead after 15 years). Twelve patients had died before 15 years and 3 patients were lost to follow-up. The mean follow-up was 17.9 years (range, 15-23 years). RESULTS:At the final follow-up, 8 knees of 39 (20.5%) had a surgical revision. The cumulative survival rate was 82.1% at 15 years and 79.4% at 20 years. The main reason of revision was progression of OA (87.5%), followed by aseptic loosening of the tibial component (12.5%). With a mean follow-up of 17.9 years, the mean PE wear was 0.061 mm/y. There was no radiographic loosening in the surviving implants and no revisions for wear. The mean functional International Knee Society score was 66.5 ± 26.8, with a mean objective score of 84.4 points ± 13.2. In the population without revision, 90.5% were satisfied or very satisfied at the latest follow-up. CONCLUSION:Lateral UKA with a fixed, all-PE tibial bearing and a femoral resurfacing implant presents a high survivorship at long term, with very low PE wear. 10.1016/j.arth.2019.01.053
    Improved Survival of Computer-Assisted Unicompartmental Knee Arthroplasty: 252 Cases With a Minimum Follow-Up of 5 Years. Chowdhry Majid,Khakha Raghbir S,Norris Mark,Kheiran Amin,Chauhan Sandeep K The Journal of arthroplasty BACKGROUND:Unicompartmental knee arthroplasty (UKA) is an underutilized implant for medial tibiofemoral arthritis despite proven benefits in performance and reduced complications. This is likely related to registry recorded higher revision rates compared with total knee arthroplasty. It is our feeling that better component alignment resulting from the usage of computer-assisted surgery should improve longer-term functional results and survival of UKAs. METHODS:Between August 2003 and June 2007, 265 medial UKAs were performed in 264 consecutive patients using navigation. RESULTS:Eighty-eight women and 176 men with an average age of 51.7 (±4.63) years were assessed for function and survival over a follow-up period of 92.6 (63-120) months (7.7 years). The final survival rate over 5 years for this cohort was 97.6% at 5 years. CONCLUSION:We conclude that computer-assisted UKA, to treat medial tibiofemoral joint arthritis, produces 5-year survival rates that are comparable with total knee arthroplasty. 10.1016/j.arth.2016.11.027
    What Is the Critical Tibial Resection Depth During Unicompartmental Knee Arthroplasty? A Biomechanical Study of Fracture Risk. Houskamp Daniel J,Tompane Trevor,Barlow Brian T The Journal of arthroplasty BACKGROUND:Fracture after medial unicompartmental knee arthroplasty (UKA) is a rare complication. Biomechanical studies evaluating association between depth of resection and maximum load to failure are lacking. The purpose of this study is to establish the relationship between depth of resection of the medial tibial plateau and mean maximum load to failure. METHODS:Medial tibial resections were performed from 2 to 10 mm in 25 standardized fourth-generation Sawbones composite tibias (Sawbones, Vashon Island, Washington). A metal-backed tibial component with a 9-mm polyethylene bearing was used (Stryker PKR). Tibias were mounted on a biomechanical testing apparatus (MTESTQuattro) and axially loaded cyclically 10 times per cycle and incrementally increased until failure occurred. RESULTS:Load to failure was recorded in 25 proximal tibia model samples after medial UKA using sequential resections from 2 to 10 mm. Analysis of variance testing identified significant differences in mean maximum load to failure between groups (P = .0003). Analysis of regression models revealed a statistically significant fit of a quadratic model (R = 0.59, P = .0001). The inflection point of this quadratic curve was identified at 5.82 mm, indicating that the maximum load to failure across experimental models in this study began to decline beyond a resection depth of 5.82 mm. CONCLUSION:In this biomechanical model, medial tibial resections beyond 5.82 mm produced a significantly lower mean load to failure using a quadratic curve model. Resections from 2 to 6 mm showed no significant differences in mean load to failure. Identification of the tibial resection depth at which the mean load to failure significantly decreases is clinically relevant as this depth may increase the risk of periprosthetic fracture after a medial UKA. 10.1016/j.arth.2020.04.005
    A survival analysis of 1084 knees of the Oxford unicompartmental knee arthroplasty: a comparison between consultant and trainee surgeons. Bottomley N,Jones L D,Rout R,Alvand A,Rombach I,Evans T,Jackson W F M,Beard D J,Price A J The bone & joint journal AIMS:The aim of this to study was to compare the previously unreported long-term survival outcome of the Oxford medial unicompartmental knee arthroplasty (UKA) performed by trainee surgeons and consultants. PATIENTS AND METHODS:We therefore identified a previously unreported cohort of 1084 knees in 947 patients who had a UKA inserted for anteromedial knee arthritis by consultants and surgeons in training, at a tertiary arthroplasty centre and performed survival analysis on the group with revision as the endpoint. RESULTS:The ten-year cumulative survival rate for revision or exchange of any part of the prosthetic components was 93.2% (95% confidence interval (CI) 86.1 to 100, number at risk 45). Consultant surgeons had a nine-year cumulative survival rate of 93.9% (95% CI 90.2 to 97.6, number at risk 16). Trainee surgeons had a cumulative nine-year survival rate of 93.0% (95% CI 90.3 to 95.7, number at risk 35). Although there was no differences in implant survival between consultants and trainees (p = 0.30), there was a difference in failure pattern whereby all re-operations performed for bearing dislocation (n = 7), occurred in the trainee group. This accounted for 0.6% of the entire cohort and 15% of the re-operations. CONCLUSION:This is the largest single series of the Oxford UKA ever reported and demonstrates that good results can be achieved by a heterogeneous group of surgeons, including trainees, if performed within a high-volume centre with considerable experience with the procedure. Cite this article: Bone Joint J 2016;(10 Suppl B):22-7. 10.1302/0301-620X.98B10.BJJ-2016-0483.R1
    Outpatient unicompartmental knee arthroplasty: who is afraid of outpatient surgery? Hoorntje Alexander,Koenraadt Koen L M,Boevé Margreet G,van Geenen Rutger C I Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:In recent years, duration of hospitalisation after knee arthroplasty has decreased and fast track and outpatient surgery protocols have been developed. Studies have shown that outpatient surgery is feasible, safe, and cost effective. However, the psychological well-being of patients undergoing outpatient surgery has never been described before. The purpose of this study was to investigate how patients experience outpatient surgery for unicompartmental knee arthroplasty (UKA), examining levels of anxiety and depression, satisfaction, and pain. It was hypothesized that the same-day discharge following UKA would not result in higher levels of anxiety and depression, compared to the standard fast-track surgery. METHODS:This case-controlled study included 20 patients undergoing UKA in an outpatient surgery setting and 20 patients undergoing the standard fast-track procedure. The Hospital Anxiety and Depression Scale (HADS, 0-42, lower is better) and numeric rating scales (NRS, 0-10) for pain and satisfaction were collected preoperatively, on the day of surgery, on the first, second, and seventh postoperative days and after 6 and 12 weeks. The Oxford Knee Score (OKS), the KOOS, EuroQoL-5D, and Net Promoter Score (NPS) were collected preoperatively and 3 months postoperatively. RESULTS:90% of patients in the outpatient surgery group were discharged on the day of surgery. At the first postoperative day, the median HADS score was significantly lower in the outpatient surgery group compared to the fast-track group (3 vs. 8, p = 0.02), the median NRS satisfaction score was significantly higher in the outpatient surgery group (8 vs. 5, p = 0.03), and no differences existed between both groups for the NRS pain scores. At 3 month follow-up, no significant differences in improvement scores existed between both groups for the HADS, the NRS scores, and for the OKS, KOOS, EuroQoL-5D, and NPS. CONCLUSION:The results of this study emphasize the feasibility of an outpatient surgery pathway in carefully selected UKA patients. The outpatient surgery pathway is safe, and clinical outcome, including levels of anxiety and depression, satisfaction, and pain, was similar in outpatient surgery patients compared to the standard fast-track patients. LEVEL OF EVIDENCE:Case-control study, Level III. 10.1007/s00167-017-4440-y
    Patient-specific instrument for unicompartmental knee arthroplasty does not reduce the outliers in alignment or improve postoperative function: a meta-analysis and systematic review. Li Mingyang,Zeng Yi,Wu Yuangang,Liu Yuan,Wei Wenxing,Wu Limin,Peng Bo-Qiang,Li Jiayi,Shen Bin Archives of orthopaedic and trauma surgery BACKGROUND:Unsatisfactory alignment in unicompartmental knee arthroplasty (UKA) is one potential cause of postoperative failure. Patient-specific instruments (PSIs) are designed to improve the alignment of the prostheses, but the effect of PSIs on the alignment or clinical outcome is controversial and lacks validated evidence. We conducted a meta-analysis and systematic review to determine the effect of PSIs on UKA outcomes for the first time. MATERIALS AND METHODS:A systematic literature search in MEDLINE, EMBASE, CNKI (Chinese database) and Cochrane Central Register of Controlled Trials (up to June 2019) was performed to collect studies that compared PSIs with conventional instruments. Two reviewers independently screened all the records on the basis of inclusion and exclusion criteria. Quality assessments with Cochrane's quality assessment tool or Newcastle-Ottawa scale (NOS) were conducted, the data were extracted, and statistical analyses were completed. RESULTS:Ten studies with 444 knees were included. The meta-analysis confirmed that PSIs contributed to reduced errors in the alignment of the femoral compartment in the sagittal plane (mean difference = - 2.53, CI [- 3.14, - 1.99], P < 0.01) and the tibial compartment in both the coronal (mean difference = - 0.97, CI [- 1.44, - 0.49], P < 0.01) and the sagittal plane (mean difference = - 1.29, CI [- 1.81, - 0.76], P < 0.01). One study supported that PSIs reduced outliers in inexperienced surgeons; however, all studies investigating PSIs among experienced surgeons suggested that PSIs cannot reduce the percentage of outliers. There was no significant difference in the postoperative score (mean difference = - 0.06, CI [- 0.36, 0.23], P = 0.68) or rate of complications (RR = 1.02, CI [0.15, 6.79], P = 0.99) between PSIs and conventional instruments. CONCLUSION:The findings of this study suggest PSIs could not reduce the percentage of outliers in UKA patients for experts, and postoperative scores and complication rates are not improved by PSIs, compared with conventional instruments. Based on this meta-analysis and systematic review, no practical benefit to UKAs in experts was detected in PSIs. The findings of this study also suggest that PSIs improved alignment of UKA and might be beneficial to inexperienced surgeons, but it is still unclear whether this improvement is clinically significant and the evidence of inexperienced surgeons is limited. Therefore, more high-quality RCTs are need to be carried out in the future. 10.1007/s00402-020-03429-z
    Risk factors of postoperative valgus malalignment in mobile-bearing medial unicompartmental knee arthroplasty. Zhang Qidong,Zhang Qian,Guo Wanshou,Gao Man,Ding Ran,Wang Weiguo Archives of orthopaedic and trauma surgery OBJECTIVE:The aim of this observational study was to investigate the risk factors of postoperative valgus malalignment after mobile-bearing medial unicompartmental knee arthroplasty (UKA). METHODS:We retrospectively evaluated radiographic and surgical characteristics in 122 consecutive Oxford phase 3 UKAs. According to postoperative hip-knee-ankle angle (HKAA), 24 knees were sorted into group valgus with HKAA > 180° and 98 knees were sorted into group non-valgus with HKAA ≤ 180°. Logistic regression was performed to analyze risk factors including age, gender, BMI, side, preoperative limb alignment HKAA, preoperative LDFA, MPTA, FTFA, thickness of polyethylene bearing insert, tibial prothesis size, femoral prothesis size, medial tibial cut thickness, thickness of distal femoral mill, prothesis angle of coronal, and sagittal plane. RESULTS:The mean mechanical preoperative HKAA of 174.39°±4.23° was corrected to 178.18°±3.49° postoperatively (t = - 13.45, p = 0.000). The mean of postoperative HKAA in valgus group and non-valgus group was 183.45 ± 2.21° and 176.88 ± 2.35°, respectively (t = 12.44, p = 0.000). After statistical analysis with univariate analysis, eight risk factor variables among 16 independent variables were identified as potential predictors with p value ≤ 0.1. Multivariate logistic regression analysis for these eight potential predictors revealed that tibial cut (p = 0.046), LDFA (p = 0.003), MPTA (p = 0.011), and FTFA (p = 0.008) were significant risk factors predicting postoperative valgus malalignment after mobile-bearing UKA. CONCLUSIONS:Preoperative smaller LDFA, FTFA, larger MPTA and less medial tibial cut thickness were significantly associated with postoperative valgus malalignment in mobile-bearing UKA. 10.1007/s00402-018-3070-2
    Sports, Physical Activity and Patient-Reported Outcomes After Medial Unicompartmental Knee Arthroplasty in Young Patients. Walker Tilman,Streit Julia,Gotterbarm Tobias,Bruckner Thomas,Merle Christian,Streit Marcus R The Journal of arthroplasty One hundred-and-one patients age 60 or younger following medial mobile bearing UKA were reviewed retrospectively with a minimum follow-up of 2 years using the Schulthess activity score, Tegner, UCLA and SF-36 score to assess their level of physical activity and quality of life. Patients showed a rapid recovery and resumption of their activities with a return-to-activity rate of 93%. Most common activities were low impact, whereas high-impact activities showed a significant decrease. Precaution was found to be the main reason for a decrease in the level of activity. The results of this study demonstrate that patients age 60 or younger following medial UKA were able to return to regular physical activities with almost two-thirds of the patients reaching a high activity level (UCLA≥7). 10.1016/j.arth.2015.05.031
    Return to sports, recreational activity and patient-reported outcomes after lateral unicompartmental knee arthroplasty. Walker Tilman,Gotterbarm Tobias,Bruckner Thomas,Merle Christian,Streit Marcus R Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:As the indication for unicompartmental knee arthroplasty (UKA) in recent years has been extended to young and more active patients, the expectations concerning the postoperative level of activity are high. The aim of the following study was to survey the activity level and the health-related quality of life of patients following lateral UKA. METHODS:Forty-five patients were surveyed to determine their sporting and recreational activities at a mean follow-up of 3 years (range 2.0-4.3 years) after lateral UKA. We also assessed health-related quality of life of our patients at the time of the survey by use of the SF-36 Health Survey. RESULTS:Before the onset of the first restricting symptoms, 42 of 45 (93 %) patients were active in at least one sport compared to 43 of 45 (96 %) patients after surgery resulting in a return to activity rate of 98 %. Within 3 months, 56 % returned to their activities after surgery and 78 % within 6 months. The mean postoperative UCLA score was 6.7 (±1.5). Two-thirds of the patients reached a high activity level (UCLA ≥7). Most common activities after surgery were biking, hiking and long walks. While high-impact activities showed a significant decrease, low-impact activities showed a significant increase. The main reason for a decrease in patients' level of activity was precaution. There are no statistically significant differences in the postoperative scores of our patients and those of a matched healthy reference population in the SF-36 scores. CONCLUSION:The results of the present study demonstrate that a vast majority (98 %) of our patients independent to age or gender returned to sports and recreational activity after lateral UKA. Two-thirds of the patients reached a high activity level. Activities patients were most participating in were low- or mid-impact, whereas high-impact activities were mostly given up. Further follow-up is necessary to assess the effect of activity on implant fixation and wear. LEVEL OF EVIDENCE:Retrospective case series, Level IV. 10.1007/s00167-014-3111-5
    Patients With Poor Baseline Mental Health Undergoing Unicompartmental Knee Arthroplasty Have Poorer Outcomes. Goh Graham Seow-Hng,Liow Ming Han Lincoln,Pang Hee-Nee,Tay Darren Keng-Jin,Lo Ngai-Nung,Yeo Seng-Jin The Journal of arthroplasty BACKGROUND:The relationship between mental health and outcomes of unicompartmental knee arthroplasty (UKA) remains unclear. Poor preoperative mental health may be caused by pain and functional limitations associated with knee arthritis. We aimed at (1) investigating the effect of preoperative mental health on early outcomes and (2) assessing whether mental health improves after UKA. METHODS:Prospectively collected registry data of 1473 medial UKAs performed at a single institution in 2007-2014 were reviewed. Linear regression was used to determine improvement in mental health up to 2 years according to preoperative Short-Form 36 Mental Component Summary (MCS). Patients were stratified into low MCS (<50, n = 579) and high MCS (≥50, n = 894). The Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), Short-Form 36, satisfaction, and expectation fulfilment were compared at 6 months and 2 years. RESULTS:The mean preoperative MCS was 41.2 in low MCS group and 58.6 in high MCS group (P < .001). The high MCS group had higher KSKS, KSFS, OKS, and Physical Component Summary, and a greater proportion of patients were satisfied and had expectations fulfilled at 6 months and 2 years (P < .05). However, the low MCS group demonstrated greater improvement in KSKS, KSFS, and OKS (P < .05). Lower preoperative MCS score was predictive of greater improvement in MCS (coefficient = -0.662, R = -0.602, P < .001). CONCLUSION:Patients with poor mental health benefit from greater improvements in their mental health and knee function after UKA, but also have a greater dissatisfaction. 10.1016/j.arth.2018.02.074
    Are Revisions of Unicompartmental Knee Arthroplasties More Like a Primary or Revision TKA? Lunebourg Alexandre,Parratte Sébastien,Ollivier Matthieu,Abdel Matthew P,Argenson Jean-Noël A The Journal of arthroplasty If revision is required, most unicompartmental arhroplasties (UKAs) are converted to total knee arthroplasties (TKAs) and conflicting results regarding surgical complexity and outcome have been reported in publications. 48 UKAs converted to a TKA between 1998 and 2009 were matched based on age, gender, and body mass index, pre-operative Knee Society Score, length of follow-up, and date of the index surgery to 48 primary TKAs and 48 revision TKAs. Surgical characteristics, clinical outcomes, and complications were compared at a mean follow-up of 7 ± 4 years. Even if a revision of UKA is technically less demanding than a revision TKA, functional scores, quality of life, complications and survival rate after revision UKA are more comparable to a revision than primary TKA. 10.1016/j.arth.2015.05.042
    Long-term outcomes of unicompartmental knee arthroplasty in patients requiring high flexion: an average 10-year follow-up study. Seo Seung-Suk,Kim Chang-Wan,Lee Chang-Rack,Kwon Yong-Uk,Oh Minkyung,Kim Ok-Gul,Kim Chang-Kyu Archives of orthopaedic and trauma surgery INTRODUCTION:To evaluate the long-term survival of unicompartmental knee arthroplasty (UKA) in the Asian population and assess differences in clinical outcomes between mobile- and fixed-bearing UKA. MATERIALS AND METHODS:Among 111 cases of UKA that were performed by 1 surgeon from January 2002 to December 2009, we retrospectively reviewed 96 cases (36 mobile-bearing, 62 fixed-bearing) for this study. We examined cause of revision or failure, type of reoperation/revision, and duration from the surgery date to the revision upon reviewing the medical record. Survival analysis was conducted using the Kaplan-Meier method. Functional outcomes were evaluated based on range of motion and patient-reported outcome (PRO) measures (Knee Injury and Osteoarthritis Outcome Score) for cases with at least 8 years of follow-up (average, 10.2 years). RESULTS:Overall, the 10-year survival was 88% [95% confidence interval (CI) 0.81-0.95], and the estimated mean survival time was 13.4 years (95% CI 12.5-14.2). In a comparison of survival between the mobile- and fixed-bearing groups, the former had a 10-year survival of 85% (95% CI, 0.72-0.97) and an estimated mean survival time of 13.5 years (95% CI 12.2-14.7) and the latter had a 10-year survival of 90% (95% CI 0.82-0.99) and an estimated mean survival time of 13.4 years (95% CI 12.3-14.4). Thus, there was no significant difference in survival between the two groups (log-rank test, p = 0.718). In addition, no significant difference in functional outcomes was observed between the two groups (p > 0.05 for all). CONCLUSIONS:UKA performed in the Asian population showed a relatively good functional outcome and survival rate at an average 10-year follow-up. No difference in survival and PROs was observed according to the bearing type. Although the present study demonstrated a good survival rate, similar to that in other Western studies, further studies investigating the impact of the Asian lifestyle on the long-term survival of UKA is necessary. 10.1007/s00402-019-03268-7
    A Comparison of Mobile and Fixed-Bearing Unicompartmental Knee Arthroplasty at a Minimum 10-Year Follow-up. Neufeld Michael E,Albers Anthony,Greidanus Nelson V,Garbuz Donald S,Masri Bassam A The Journal of arthroplasty BACKGROUND:The long-term survivorship and functional outcomes of the mobile-bearing (MB) compared to the fixed-bearing (FB) unicompartmental knee arthroplasty (UKA) implant design remain a topic of debate. The aim of the current study was to compare the survivorship and functional outcomes of MB and FB UKA at a minimum 10-year follow-up. METHODS:We retrospectively reviewed 106 consecutive medial UKAs (89 patients) from our institution with a minimum 10-year follow-up. The 38 MB and 68 FB knees had follow-up of 14.2 years (12.9-15.5) and 11.5 years (10.2-15.1), respectively. Validated patient-reported outcomes and radiographs were evaluated as were etiology, timing, and complexity of revision. Kaplan-Meier 10-year survival was calculated with revision to total knee arthroplasty as the end point. RESULTS:The 10-year survival was 82.9% (95% confidence interval [CI] 65.8-91.9) for MB and 90.9% (95% CI 79.4-96.2) for FB UKA (P = .102), and 88.0% (95% CI 79.3-93.2) for the entire cohort. Patient outcomes were similar between groups, as were timing and etiologies for revision to total knee arthroplasty. One-third of revisions required either stems or tibial augments, and of these, all were of MB design. CONCLUSION:Survival and functional outcomes were similar between MB and FB designs. One-third of revisions required either stems or augments, all were of MB design. 10.1016/j.arth.2018.01.001
    Meta-Review of the Quantity and Quality of Evidence for Knee Arthroplasty Devices. Gagliardi Anna R,Ducey Ariel,Lehoux Pascale,Ross Sue,Trbovich Patricia,Easty Anthony,Bell Chaim,Takata Julie,Pabinger Christof,Urbach David R PloS one INTRODUCTION:Some cardiovascular devices are licensed based on limited evidence, potentially exposing patients to devices that are not safe or effective. Research is needed to ascertain if the same is true of other types of medical devices. Knee arthroplasty is a widely-used surgical procedure yet implant failures are not uncommon. The purpose of this study was to characterize available evidence on the safety and effectiveness of knee implants. METHODS:A review of primary studies included in health technology assessments (HTA) on total (TKA) and unicompartmental knee arthroplasty (UKA) was conducted. MEDLINE, EMBASE, CINAHL, Cochrane Library and Biotechnology & BioEngineering Abstracts were searched from 2005 to 2014, plus journal tables of contents and 32 HTA web sites. Patients were aged 18 and older who underwent primary TKA or UKA assessed in cohort or randomized controlled studies. Summary statistics were used to report study characteristics. RESULTS:A total of 265 eligible primary studies published between 1986 and 2014 involving 59,217 patients were identified in 10 HTAs (2 low, 7 moderate, 1 high risk of bias). Most evaluated TKA (198, 74.5%). The quality of evidence in primary studies was limited. Most studies were industry-funded (23.8%) or offered no declaration of funding or conflict of interest (44.9%); based on uncontrolled single cohorts (58.5%), enrolled fewer than 100 patients (66.4%), and followed patients for 2 years or less (UKA: single cohort 29.8%, comparative cohort 16.7%, randomized trial 25.0%; TKA: single cohort 25.0%, comparative cohort 31.4%, randomized trial 48.6%). Furthermore, most devices were evaluated in only one study (55.3% TKA implants, 61.1% UKA implants). CONCLUSIONS:Patients, physicians, hospitals and payers rely on poor-quality evidence to support decisions about knee implants. Further research is needed to explore how decisions about the use of devices are currently made, and how the evidence base for device safety and effectiveness can be strengthened. 10.1371/journal.pone.0163032
    Cementless fixation in medial unicompartmental knee arthroplasty: a systematic review. Campi S,Pandit H G,Dodd C A F,Murray D W Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The aim of this study was to evaluate clinical outcome, failures, implant survival, and complications encountered with cementless fixation in unicompartmental knee arthroplasty (UKA). METHODS:A systematic review of the literature on cementless fixation in UKA was performed according to the PRISMA guidelines. The following database was comprehensively searched: PubMed, Cochrane, Medline, CINAHL, Embase, and Google Scholar. The keywords "unicompartmental", "unicondylar", "partial knee arthroplasty", and "UKA" were combined with each of the keyword "uncemented", "cementless" and "survival", "complications", and "outcome". The following data were extracted: demographics, clinical outcome, details of failures and revisions, cumulative survival, and complications encountered. The risk of bias of each study was estimated with the MINORS score and a further scoring system based on the presence of the primary outcomes. RESULTS:From a cohort of 63 studies identified using the above methodology, 10 papers (1199 knees) were included in the final review. The mean follow-up ranged from 2 to 11 years (median 5 years). The 5-year survival ranged from 90 to 99 % and the 10-year survival from 92 to 97 %. There were 48 revisions with an overall revision rate of 0.8 per 100 observed component-years. The most common cause of failure was progression of osteoarthritis in the retained compartment (0.9 %). The cumulative incidence of complications and revisions was comparable to that reported in similar studies on cemented UKAs. The advantages of cementless fixation include faster surgical time, avoidance of cementation errors, and lower incidence of radiolucent lines. CONCLUSIONS:Cementless fixation is a safe and effective alternative to cementation in medial UKA. Clinical outcome, failures, reoperation rate, and survival are similar to those reported for cemented implants with lower incidence of radiolucent lines. LEVEL OF EVIDENCE:IV. 10.1007/s00167-016-4244-5
    Sports activities after medial unicompartmental knee arthroplasty Oxford III-what can we expect? Pietschmann Matthias F,Wohlleb Lisa,Weber Patrick,Schmidutz Florian,Ficklscherer Andreas,Gülecyüz Mehmet F,Safi Elem,Niethammer Thomas R,Jansson Volkmar,Müller Peter E International orthopaedics PURPOSE:Excellent long-term results have been reported for implantation of unicompartmental knee arthroplasty (UKA). In many patients the desire for improvement in function often includes an aspiration to return to sports. The purpose of our study was to evaluate physical activities after medial Oxford-III (Biomet) UKA surgery. METHODS:Patients' physical activity before and after the surgery was assessed using a self reporting questionnaire. We used the Oxford knee scoring system (OKS), the WOMAC-, the Knee society- (KSS) and the UCLA-score to assess postoperative knee function. The mean follow-up was 4.2 years. The female-to-male ratio was 1.3:1. The mean age at surgery was 65.3 years. RESULTS:Of the 131 patients studied 78 participated in some kind of sports before surgery (mean age 64.4 years), while 53 patients did not perform any sports (mean age 66.5 years) (p > 0.05). At follow-up the patients in the active group were significantly younger than the patients in the inactive group (p < 0.05). The majority of patients (80.1 %) returned to their level of sports activity after UKA surgery. Six patients took up sports after surgery while 15 patients stopped their sports. Among the active patients we found a shift from high- towards low-impact sports. The active patients had significantly higher scores for the OKS, KSS, WOMAC and UCLA score. The complication rate was comparable in both groups. CONCLUSION:Our study demonstrates that a high degree of patient satisfaction in terms of sports activity can be achieved using the Oxford-III UKA for medial osteoarthritis. 10.1007/s00264-012-1710-7
    Formal Physical Therapy May Not Be Necessary After Unicompartmental Knee Arthroplasty: A Randomized Clinical Trial. Fillingham Yale A,Darrith Brian,Lonner Jess H,Culvern Chris,Crizer Meredith,Della Valle Craig J The Journal of arthroplasty BACKGROUND:The purpose of this randomized clinical trial was to compare formal outpatient physical therapy (PT) and unsupervised home exercises after unicompartmental knee arthroplasty (UKA). METHODS:Fifty-two patients were randomized to 6 weeks of outpatient PT or an unsupervised home exercise program after UKA. The primary outcome was change in range of motion at 6 weeks with secondary outcomes including total arc of motion, Knee Society Score, Knee Injury and Osteoarthritis Outcome Score Jr, Lower Extremity Functional Scale, and Veterans Rands-12 score. RESULTS:Twenty-five patients received outpatient PT, 22 patients the self-directed exercise program, while 3 patients deviated from the protocol, 1 patient withdrew, and 1 patient was lost to follow-up. There was no difference in the change of range of motion (P = .43) or total arc of motion at 6 weeks (P = .17) between the groups and likewise no significant differences were found in any of the secondary outcomes. Two patients who crossed over from the unsupervised home exercise program to formal outpatient PT within the first 2 weeks postoperatively required a manipulation under anesthesia. CONCLUSIONS:Our results suggest self-directed exercises may be appropriate for most patients following UKA. However, there is a subset of patients who may benefit from formal PT. 10.1016/j.arth.2018.02.049
    Medial compartment knee osteoarthritis: age-stratified cost-effectiveness of total knee arthroplasty, unicompartmental knee arthroplasty, and high tibial osteotomy. Smith William B,Steinberg Joni,Scholtes Stefan,Mcnamara Iain R Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:To compare the age-based cost-effectiveness of total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and high tibial osteotomy (HTO) for the treatment of medial compartment knee osteoarthritis (MCOA). METHODS:A Markov model was used to simulate theoretical cohorts of patients 40, 50, 60, and 70 years of age undergoing primary TKA, UKA, or HTO. Costs and outcomes associated with initial and subsequent interventions were estimated by following these virtual cohorts over a 10-year period. Revision and mortality rates, costs, and functional outcome data were estimated from a systematic review of the literature. Probabilistic analysis was conducted to accommodate these parameters' inherent uncertainty, and both discrete and probabilistic sensitivity analyses were utilized to assess the robustness of the model's outputs to changes in key variables. RESULTS:HTO was most likely to be cost-effective in cohorts under 60, and UKA most likely in those 60 and over. Probabilistic results did not indicate one intervention to be significantly more cost-effective than another. The model was exquisitely sensitive to changes in utility (functional outcome), somewhat sensitive to changes in cost, and least sensitive to changes in 10-year revision risk. CONCLUSIONS:HTO may be the most cost-effective option when treating MCOA in younger patients, while UKA may be preferred in older patients. Functional utility is the primary driver of the cost-effectiveness of these interventions. For the clinician, this study supports HTO as a competitive treatment option in young patient populations. It also validates each one of the three interventions considered as potentially optimal, depending heavily on patient preferences and functional utility derived over time. 10.1007/s00167-015-3821-3
    Unicompartmental knee arthroplasty in patients over 75 years: a definitive solution? Iacono Francesco,Raspugli Giovanni Francesco,Akkawi Ibrahim,Bruni Danilo,Filardo Giuseppe,Budeyri Aydin,Bragonzoni Laura,Presti Mirco Lo,Bonanzinga Tommaso,Marcacci Maurilio Archives of orthopaedic and trauma surgery INTRODUCTION:The purpose of this study was to perform a mid-long-term clinical and radiographic evaluation of the results obtained in patients older than 75 years treated with minimally invasive unicompartmental knee arthroplasty (UKA). The hypothesis was that UKA is a viable solution for the definitive treatment of localized disease in this age group, with good results and a low failure rate. METHODS:An all-poly tibial component UKA was applied with a minimally invasive technique. Sixty-seven knees in patients with a minimum age of 75 years were evaluated at mean 9 years' follow-up. The Oxford knee score, Knee Society Score, WOMAC score, Visual Analogue Scale (VAS) for pain self-assessment and range of motion (ROM) were determined, as well as weight-bearing antero-posterior and laterolateral radiographs. RESULTS:All clinical scores, as well as VAS and ROM, improved significantly at 9-year follow-up, and the outcome was considered good or excellent in 92.6% of the patients. Radiographic results showed that both tibial plateau angle and posterior tibial slope angles were maintained, whereas femoro-tibial angle was significantly changed at follow-up. Further analysis showed no significant correlation between clinical scores and body mass index, whereas the clinical outcome was correlated with the ROM obtained. Only two failures and one major post-operative complication were observed. CONCLUSIONS:UKA is a viable option for treating unicompartmental knee osteoarthritis. With the proper indications and an accurate technique UKA may be indicated also in very elderly patients with reduced complications and morbidity, and excellent survivorship. 10.1007/s00402-015-2323-6
    Feasibility and safety of performing outpatient unicompartmental knee arthroplasty. Cross Michael B,Berger Richard International orthopaedics PURPOSE:Unicompartmental knee arthroplasty (UKA) has a faster short-term recovery than total knee arthroplasty (TKA). The purpose of this study was to determine the feasibility and safety of performing outpatient UKAs in a consecutive group of patients presenting with unicompartmental knee osteoarthritis. METHODS:A total of 105 consecutive patients underwent unicompartmental arthroplasty before noon with the intention of being discharged as an outpatient. All patients followed an established rapid recovery pathway to facilitate a same-day discharge. Post-operative complications and hospital readmissions were retrospectively recorded for all patients at one week and at three months after surgery. RESULTS:All of the 105 patients (100 %) indicated for outpatient UKA could be discharged home on the same day of surgery. No patients required readmission within the first week post-operatively, while one patient required readmission between week one and week 12. The single patient who required readmission developed a post-operative infection requiring irrigation/debridement with polyethylene liner exchange and intravenous antibiotics. CONCLUSION:Using an established, multidisciplinary, rapid recovery protocol, outpatient UKA is safe and feasible in the vast majority of patients. 10.1007/s00264-013-2214-9
    Morphologic difference and size mismatch in the medial and lateral tibial condyles exist with respect to gender for unicompartmental knee arthroplasty in the Korean population. Koh Yong-Gon,Nam Ji-Hoon,Chung Hyun-Seok,Lee Hwa-Yong,Kang Kyoung-Tak Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The purpose of this study was to characterize the geometry of the proximal tibia in both genders in the Korean population. Anthropometric data on the medial and lateral tibial condyles of the osteoarthritic knees of 149 males and 814 females were obtained using three-dimensional magnetic resonance imaging. METHODS:In the medial and lateral proximal tibial condyles, the anteroposterior (AP) dimension, widest dimension (WD) at defined points, and condylar aspect ratio were evaluated. These measurements were compared with similar dimensions of the tibial components from five commonly used unicompartmental knee arthroplasty (UKA) designs in Korea. RESULTS:Both the AP dimension and WD in the medial and lateral tibial condyles of the male patients were significantly greater than those of the female patients (P < 0.05). In addition, the AP dimension and WD were greater in the medial than in the lateral tibial condyle (P < 0.05). There was WD overhang in three and two prostheses in the medial and lateral tibial condyles, respectively. A decrease in the condylar aspect ratio with an increasing AP dimension was found in the medial and lateral tibial condyles for both the male and female patients. CONCLUSIONS:Smaller medial and lateral tibial condylar dimensions are more frequent in Korean women than in Korean men. This study highlights the finding that conventional UKA designs lead to size mismatch in the Korean population and may indicate an important guideline on proper gender-specific UKA tibial prostheses with different WD/AP dimension aspect ratios. In addition, this study suggests that the shape of the medial tibial plateau is different to that of the lateral plateau, which can lead to a mediolateral overhang for medial UKA in an attempt to optimize the AP coverage. LEVEL OF EVIDENCE:III. 10.1007/s00167-019-05600-5
    The results of Oxford unicompartmental knee arthroplasty in the United States: a mean ten-year survival analysis. Emerson R H,Alnachoukati O,Barrington J,Ennin K The bone & joint journal AIMS:Approved by the Food and Drug Administration in 2004, the Phase III Oxford Medial Partial Knee is used to treat anteromedial osteoarthritis (AMOA) in patients with an intact anterior cruciate ligament. This unicompartmental knee arthroplasty (UKA) is relatively new in the United States, and therefore long-term American results are lacking. PATIENTS AND METHODS:This is a single surgeon, retrospective study based on prospectively collected data, analysing a consecutive series of primary UKAs using the Phase III mobile-bearing Oxford Knee and Phase III instrumentation. Between July 2004 and December 2006, the senior author (RHE) carried out a medial UKA in 173 patients (213 knees) for anteromedial osteoarthritis or avascular necrosis (AVN). A total of 95 patients were men and 78 were women. Their mean age at surgery was 67 years (38 to 89) and mean body mass index 29.87 kg/m2 (17 to 62). The mean follow-up was ten years (4 to 11). RESULTS:Survivorship of the Oxford UKA at ten years was 88%, using life table analysis. Implant survivorship at ten years was 95%. The most common cause for revision was the progression of osteoarthritis in the lateral compartment. The mean knee score element of the American Knee Society Score (AKSS) was 50 pre-operatively and increased to 93 post-operatively. The mean AKSS function score was 56 pre-operatively rising to 78 post-operatively CONCLUSION: This ten-year follow-up study of the Oxford UKA undertaken in the United States shows good survivorship and excellent function in a wide selection of patients with AMOA and AVN. Cite this article: Bone Joint J 2016;98-B(10 Suppl B):34-40. 10.1302/0301-620X.98B10.BJJ-2016-0480.R1
    Sports activities before and after medial unicompartmental knee arthroplasty using the new Heidelberg Sports Activity Score. Jahnke Alexander,Mende Johannes Karl,Maier Gerrit Steffen,Ahmed Gafar Adam,Ishaque Bernd Alexander,Schmitt Holger,Rickert Markus,Clarius Michael,Seeger Jörn Bengt International orthopaedics PURPOSE:The purpose of our study was to investigate the change of sports activities before and after medial unicompartmental knee arthroplasty (UKA) with the use of the Heidelberg Sports Activity Score (HAS). METHODS:The Heidelberg Sports Activity Score (HAS) as well as FFb-H-OA, Oxford-12-Score, Tegner, UCLA and ACS were carried out to assess sports activities in 157 patients with medial osteoarthritis of the knee joint before and after UKA. The newly developed HAS also records the important duration and the sporting activity. RESULTS:Patients practiced sports in a more deliberate manner after UKA. Hiking, cycling and swimming were the sports most increased after surgery. Patients ≤65 years of age were sportier than those >65 years. Men were sportier than women, but all became sportier postoperatively. Patients with a high body mass index (BMI) are less sporty at first, but then increase their sports activity after surgery. CONCLUSIONS:HAS is an effective and valid assessment scale for evaluating sports activities before and after knee replacement. 10.1007/s00264-014-2524-6
    Computer-assisted unicompartmental knee arthroplasty using dedicated software versus a conventional technique. Manzotti Alfonso,Cerveri Pietro,Pullen Chris,Confalonieri Norberto International orthopaedics PURPOSE:The aim of this study was to retrospectively compare the results of two matched-paired groups of patients who had undergone a medial unicompartmental knee arthroplasty (UKA) performed using either a conventional or a non-image-guided navigation technique specifically designed for unicompartmental prosthesis implantation. METHODS:Thirty-one patients with isolated medial-compartment knee arthritis who underwent an isolated navigated UKA were included in the study (group A) and matched with patients who had undergone a conventional medial UKA (group B). The same inclusion criteria were used for both groups. At a minimum of six months, all patients were clinically assessed using the Knee Society Score (KSS) and the Western Ontario and McMaster Osteoarthritis Index (WOMAC) index. Radiographically, the frontal-femoral-component angle, the frontal-tibial-component angle, the hip-knee-ankle angle and the sagittal orientation of components (slopes) were evaluated. Complications related to the implantation technique, length of hospital stay and surgical time were compared. RESULTS:At the latest follow-up, no statistically significant differences were seen in the KSS, function scores and WOMAC index between groups. Patients in group B had a statistically significant shorter mean surgical time. Tibial coronal and sagittal alignments were statistically better in the navigated group, with five cases of outliers in the conventional alignment technique group. Postoperative mechanical axis was statistically better aligned in the navigated group, with two cases of overcorrection from varus to valgus in group B. No differences in length of hospital stay or complications related to implantation technique were seen between groups. CONCLUSION:This study shows that a specifically designed UKA-dedicated navigation system results in better implant alignment in UKA surgery. Whether this improved alignment results in better clinical results in the long term has yet to be proven. 10.1007/s00264-013-2215-8
    Usage of unicompartmental knee arthroplasty. Murray D W,Parkinson R W The bone & joint journal Unicompartmental knee arthroplasty (UKA) has numerous advantages over total knee arthroplasty (TKA) and one disadvantage, the higher revision rate. The best way to minimize the revision rate is for surgeons to use UKA for at least 20% of their knee arthroplasties. To achieve this, they need to learn and apply the appropriate indications and techniques. This would decrease the revision rate and increase the number of UKAs which were implanted, which would save money and patients would benefit from improved outcomes over their lifetime. Cite this article: Bone Joint J 2018;100-B:432-5. 10.1302/0301-620X.100B4.BJJ-2017-0716.R1
    Better quality of life after medial versus lateral unicondylar knee arthroplasty. Liebs Thoralf R,Herzberg Wolfgang Clinical orthopaedics and related research BACKGROUND:The number of unicompartmental knee arthroplasties (UKAs) is growing worldwide. Because lateral UKAs are performed much less frequently than medial UKAs, the limited information leaves unclear whether UKAs have comparable survival and health-related quality of life (HRQoL) of the lateral UKA to medial UKAs. QUESTIONS/PURPOSES:We therefore compared the (1) survivorship and (2) HRQoL after lateral versus medial cemented mobile-bearing UKAs and (3) determined whether there is an association of survival to modifications of surgical technique in one of three phases. METHODS:We retrospectively reviewed 558 patients who underwent mobile-bearing UKAs from 2002 to 2009. From the records we determined revision of the joint for any reason and revision for aseptic loosening. Patients reported their physical function, pain, and stiffness as measured by the WOMAC, SF-36 physical-component summary (PCS), and Lequesne knee score. Information regarding implant survival was collected for 93% of the patients. We analyzed the patients separately by three phases based on surgical changes associated with each phase (1: initial technique; 2: improved cementing; 3: additional bone resection to ensure backward sliding of the inlay without impingement). The minimum followup was 2.1 years (mean, 6 years; range, 2.1-9.8 years). RESULTS:Implant survival was 88% at 9 years. We found similar implant survival rates for medial (90%) and lateral UKAs (83%). In all HRQoL measures, patients receiving a medial UKA had better mean scores compared with patients who had a lateral UKA: WOMAC physical function (23 versus 34, respectively) and pain (21 versus 34) and SF-36 PCS (41 versus 38). There were no survival differences by surgical phase. CONCLUSIONS:Our observations suggest a medial UKA is associated with superior HRQoL when compared with a lateral UKA, although implant survival is similar. 10.1007/s11999-013-2966-y
    Unicompartmental Knee Arthroplasty vs High Tibial Osteotomy for Knee Osteoarthritis: A Systematic Review and Meta-Analysis. Cao ZhenWu,Mai XiuJun,Wang Jun,Feng EnHui,Huang YongMing The Journal of arthroplasty BACKGROUND:Prior studies have compared unicompartmental knee arthroplasty (UKA) with high tibial osteotomy (HTO) suggesting that both procedures had good clinical outcomes. However, which treatment is more beneficial for unicompartmental knee osteoarthritis is still a controversy. The purpose of our study is to obtain postoperative outcomes of revision rate, complications, function results, range of motion (ROM), and pain between the 2 procedures. METHODS:Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed and study protocol was published online at PROSPERO under registration number CRD42016049316. We searched the databases MEDLINE, EMBASE, Cochrane Library, and Web of Science up to May 2017. Articles that directly compared postoperative outcomes of UKA to HTO were included. RESULTS:A total of 10 comparative studies were included in our meta-analysis. UKA patients showed less revision rate, less complications, and less postoperative pain than HTO patients; however, HTO patients obtained more ROM. No significant difference was observed between the group accruing to the knee function scores and excellent/good surgical results. CONCLUSION:UKA offers a safe and efficient alternative to osteoarthritis reduced postoperative pain, less postoperative complication, and revision. The 2 surgical techniques showed satisfactory function results for the patients; however, the HTO group achieved superior ROM compared to the UKA group. HTO may be suitable for patients with high activity requirements. Treatment options should be carefully considered for each patient in accordance with their age, body mass index, grade of osteoarthritis, and patients' activity levels. 10.1016/j.arth.2017.10.025
    Medial unicompartmental knee arthroplasty in the ACL-deficient knee. Mancuso Francesco,Dodd Christopher A,Murray David W,Pandit Hemant Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology Symptomatic osteoarthritis (OA) of the knee develops often in association with anterior cruciate ligament (ACL) deficiency. Two distinct pathologies should be recognised while considering treatment options in patients with end-stage medial compartment OA and ACL deficiency. Patients with primary ACL deficiency (usually traumatic ACL rupture) can develop secondary OA (typically presenting with symptoms of instability and pain) and these patients are typically young and active. Patients with primary end stage medial compartment OA can develop secondary ACL deficiency (usually degenerate ACL rupture) and these patients tend to be older. Treatment options in either of these patient groups include arthroscopic debridement, reconstruction of the ACL, high tibial osteotomy (HTO) with or without ACL reconstruction, unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). General opinion is that a functionally intact ACL is a fundamental prerequisite to perform a UKA. This is because previous reports showed higher failure rates when ACL was deficient, probably secondary to wear and tibial loosening. Nevertheless in some cases of ACL deficiency with end-stage medial compartment OA, UKA has been performed in isolation and recent papers confirm good short- to mid-term outcome without increased risk of implant failure. Shorter hospital stay, fewer blood transfusions, faster recovery and significantly lower risk of developing major complications like death, myocardial infarction, stroke, deep vein thrombosis (as compared to TKA) make the UKA an attractive option, especially in the older patients. On the other hand, younger patients with higher functional demands are likely to benefit from a simultaneous or staged ACL reconstruction in addition to UKA to regain knee stability. These procedures tend to be technically demanding. The main aim of this review was to provide a synopsis of the existing literature and outline an evidence-based treatment algorithm. 10.1007/s10195-016-0402-2
    Robotic-assisted unicompartmental knee replacement offers no early advantage over conventional unicompartmental knee replacement. Wong Jason,Murtaugh Taylor,Lakra Akshay,Cooper H John,Shah Roshan P,Geller Jeffrey A Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Unicompartmental knee arthroplasty (UKA) is effective for treating degenerative joint disease in a single compartment. Robotic-arm-assisted arthroplasty (RAA) has gained popularity and has theoretical benefits of improved outcomes over conventional (CONV) UKA due to the technical precision of bone preparation. This study compares the short-term clinical outcomes, including survivorship and patient-reported functional outcomes, for a series of medial UKAs performed with RAA and CONV. METHODS:One hundred seventy-six consecutive fixed-bearing medial UKAs were retrospectively identified with a minimum follow-up of 2 years. One hundred and eighteen CONV and 58 RAA were performed. Pre- and post-operative SF12, WOMAC, and KSS Functional Questionnaires were available for all patients. RESULTS:At 2 years, both groups improved in all functional outcomes, with no significant difference between the RAA and CONV cohorts. However, the RAA cohort had a significantly longer operative time (p < 0.001) and a higher early revision rate than the CONV group (7 [12.0%] vs. 7 [6.8%]; p < 0.05). CONCLUSIONS:These results demonstrate that at short-term follow-up of 2 years, RAA was not superior to CONV in terms of functional scores and instead was associated with greater operative time and cost and lower survivorship. Therefore, at this time usage of RAA in UKA is not recommended compared to conventional UKA. Longer term studies are necessary to draw conclusions about the overall outcomes of RAA compared to CONV. LEVEL OF EVIDENCE:III. 10.1007/s00167-019-05386-6
    Postoperative fixed flexion deformity greater than 10° lead to poorer functional outcome 10 years after unicompartmental knee arthroplasty. Yeh Jared Ze Yang,Chen Jerry Yongqiang,Lim Joel Wei-An,Pang Hee Nee,Tay Darren Keng Jin,Chia Shi-Lu,Lo Ngai Nung,Yeo Seng Jin Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The primary aim of this study was to evaluate the influence of postoperative fixed flexion deformity (FFD) on the clinical outcomes 10 years after unicompartmental knee arthroplasty (UKA). The secondary aim was to identify predictors for the occurrence of postoperative FFD. METHODS:Patients who underwent UKA between 2003 and 2007 were prospectively followed up for 10 years. A total of 172 patients were categorized into 3 groups based on the amount of postoperative FFD: (1) 0° or less (Min-FFD), (2) 1°-9° (Mid-FFD), and (3) 10° or more (Max-FFD). Functional outcome was quantified using Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS). RESULTS:At 10 years after UKA, the mean KSKS and OKS were 6 ± 5 (95% CI 6-18, p = 0.050) and 5 ± 2 (95% CI 0-9, p = 0.041) points lower in patients with Max-FFD than those with Min-FFD. Other clinical outcomes were not different between groups. Patients with a higher preoperative body mass index (OR 1.122 per unit increase, 95% CI 1.006-1.253, p = 0.040) or worse preoperative FFD (OR 1.108 per unit increase, 95% CI 1.022-1.201, p = 0.013) were at increased risk of having postoperative FFD of 10° or more at 10 years after UKA. CONCLUSIONS:The clinical relevance of this study was to demonstrate the long-term negative correlation between severe postoperative FFD and functional outcome and, therefore, the importance of achieving good knee alignment after UKA. The authors recommend that FFD should be fully corrected intra-operatively if possible while preserving knee balance and stable dynamic function through full range of motion. LEVEL OF EVIDENCE:Prognostic level II. 10.1007/s00167-017-4749-6
    Revision of unicompartmental knee arthroplasty versus primary total knee arthroplasty. Craik Johnathan D,El Shafie Sherif A,Singh Vinay K,Twyman Roy S The Journal of arthroplasty The risk of revision following unicompartmental arthroplasty (UKA) is greater compared with primary total knee arthroplasty (TKA). Some surgeons report that UKA revision is straightforward with outcomes comparable to TKA. We reviewed all Oxford medial UKAs and TKAs performed at our institution over a five year period. Patient reported outcomes were compared between revised UKAs, successful UKAs and primary TKAs. Out of 546 Oxford medial UKAs, twenty-nine (5.3%) were revised at a mean of 25months. The commonest indications for revision were aseptic loosening and progression of osteoarthritis. Ten patients (34%) required augments, stemmed implants or bone grafts. Outcomes following revision were poorer than those following successful UKA and primary TKA, and were a consequence of poor pre-operative function rather than the complexity of surgery. 10.1016/j.arth.2014.10.038
    Inferior outcome of revision of unicompartmental knee arthroplasty to total knee arthroplasty compared with primary total knee arthroplasty: systematic review and meta-analysis. Lee Jin Kyu,Kim Hyun Jung,Park Jae Ok,Yang Jae-Hyuk Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The purpose of this study was to compare the revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) with primary TKA through a review of previously published studies. The hypothesis was that the revised UKA group would need additional operative procedures, including the use of stems and augments, resulting in poorer clinical outcomes than those of the primary TKA group. METHODS:A literature search of online register databases was performed to identify clinical trials that compared revised UKA to TKA with primary TKA. An electronic literature search was performed using the Medline, Embase, Cochrane Library, Web of Science, and Scopus databases. No language or date restrictions were applied. RESULTS:A total of 2034 articles were identified from a keyword search, of which 11 studies were determined as eligible. They were all retrospective comparative studies. The revised UKA to TKA group had longer operation times resulting from additional procedures such as bone grafting and use of stems and augments, higher reoperation rates, and worse postoperative clinical outcomes based on the Western Ontario and McMaster Universities Osteoarthritis Index and Oxford Knee Score than the primary TKA group, with the differences being statistically significant. CONCLUSION:UKA should not be considered an alternative procedure to TKA. LEVEL OF EVIDENCE:Therapeutic Level III. 10.1007/s00167-018-4909-3
    Medial Unicondylar Knee Arthroplasty Improves Patellofemoral Congruence: a Possible Mechanistic Explanation for Poor Association Between Patellofemoral Degeneration and Clinical Outcome. Thein Ran,Zuiderbaan Hendrik A,Khamaisy Saker,Nawabi Danyal H,Poultsides Lazaros A,Pearle Andrew D The Journal of arthroplasty The purpose was to determine the effect of medial fixed bearing unicondylar knee arthroplasty (UKA) on postoperative patellofemoral joint (PFJ) congruence and analyze the relationship of preoperative PFJ degeneration on clinical outcome. We retrospectively reviewed 110 patients (113 knees) who underwent medial UKA. Radiographs were evaluated to ascertain PFJ degenerative changes and congruence. Clinical outcomes were assessed preoperatively and postoperatively. The postoperative absolute patellar congruence angle (10.05 ± 10.28) was significantly improved compared with the preoperative value (14.23 ± 11.22) (P = 0.0038). No correlation was found between preoperative PFJ congruence or degeneration severity, and WOMAC scores at two-year follow up. Pre-operative PFJ congruence and degenerative changes do not affect UKA clinical outcomes. This finding may be explained by the post-op PFJ congruence improvement. 10.1016/j.arth.2015.05.034
    Valgus Correctability and Meniscal Extrusion Were Associated With Alignment After Unicompartmental Knee Arthroplasty. Ishibashi Kyota,Sasaki Eiji,Otsuka Hironori,Kazushige Koyama,Yamamoto Yuji,Ishibashi Yasuyuki Clinical orthopaedics and related research BACKGROUND:Appropriate postoperative lower limb alignment is one important element of a successful unicompartmental knee arthroplasty (UKA). To predict postoperative alignment, it is important to investigate the association between preoperative imaging evaluations and lower limb alignment after medial UKA. QUESTIONS/PURPOSES:(1) Do preoperative valgus stress radiographic and MRI measurements (% mechanical axis, hip-knee-ankle angle, medial meniscal extrusion distance, and osteophyte area at the medial femur and tibia) correlate with postoperative lower limb alignment after UKA; and (2) Can useful cutoffs be calculated in advance of surgery for those findings that were associated with coronal-plane overcorrection? METHODS:We retrospectively analyzed 125 patients with medial knee pain who underwent UKA from January 2012 to October 2018. Valgus stress radiography and MRI were performed routinely to assess the knee. Valgus stress radiography was obtained with the patient supine with the knee in full extension and a firm manual valgus force applied to the knee. Full-length weightbearing radiography was performed 3 months after surgery. There were 12% (15) of patients who did not undergo MRI, and 4% (five) of patients who did not receive the postoperative full-length weightbearing radiograph and they were excluded, leaving 84% (105) of patients available for analysis. There were 27 men and 78 women with a mean (range) age of 77 years ± 6 years (60 to 87). The preoperative diagnosis was medial osteoarthritis in 99 patients and osteonecrosis of the medial femoral condyle in six. To investigate the associations, we routinely measured % mechanical axis using radiography, and also measured the medial meniscal extrusion distance and osteophyte area at the medial femur and tibia using MRI after surgery. Medial meniscus extrusion distance was defined as the distance from the outermost edge of the medial meniscus to a line connecting the femoral and tibial cortices. From these parameters, postoperative alignment was estimated using regression and receiver operating characteristic curve analyses. Variables with p < 0.05 were included. RESULTS:The % mechanical axis on the valgus stress radiograph and medial meniscal extrusion distance were correlated with postoperative lower limb alignment after UKA (adjusted correlation coefficient 0.72; p < 0.001, adjusted correlation coefficient 0.2; p = 0.003, respectively). The estimated % mechanical axis on the postoperative weightbearing radiograph was equal to -0.27 + 0.86% (% mechanical axis on valgus stress radiograph) + 1.14 mm (medial meniscal extrusion distance). Using a cutoff point of 36%, the % mechanical axis on valgus stress radiograph was associated with overcorrection after UKA (area under the curve: 0.89; odds ratio 14 [95% CI 0.75 to 0.95]; p < 0.001, sensitivity 77.8%, specificity 80.9%). CONCLUSIONS:The overcorrection of a varus knee on a valgus stress radiograph before UKA and the increased extrusion of the medial meniscus on preoperative MRI was associated with a greater likelihood of overcorrected alignment after UKA. Future studies should conduct long-term follow-up of malalignment patients to assess the possible complications. LEVEL OF EVIDENCE:Level III, diagnostic study. 10.1097/CORR.0000000000001260
    Anterior cruciate ligament reconstruction after unicompartmental knee arthroplasty. Citak Musa,Bosscher Marianne Roberta Frederiek,Citak Mustafa,Musahl Volker,Pearle Andrew D,Suero Eduardo M Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:ACL deficiency may cause abnormal knee kinematics and is associated with a tenfold increase in surgical failures after unicompartmental knee arthroplasty, such as aseptic loosening of the tibial compartment and medial bearing instability. The current investigators hypothesized that in a knee with UKA, single-bundle ACL reconstruction would restore tibiofemoral translation to levels similar to those of the intact ACL. METHODS:Two fresh frozen pelvis-to-toes specimens (four paired knees) were used. On each knee, medial unicompartmental knee arthroplasty was performed by a single surgeon. ACL reconstructions were performed by conventional single-bundle technique. Three trials of Lachman and pivot shift tests were performed and recorded for each knee with the ACL-intact, after sectioning the ACL and after single-bundle ACL reconstruction. A mechanized pivot shifter was used to perform the pivot shift maneuvers. A surgical navigation system (Praxim Grenoble, France) simultaneously tracked tibiofemoral kinematics. RESULTS:There was a significant difference in lateral compartment translation during the Lachman and pivot shift tests between the ACL-intact/UKA knee and the ACL-deficient/UKA knee (P < 0.05). There was no significant difference in lateral compartment translation during the Lachman and pivot shift tests between the intact/UKA knee and the ACL-reconstructed/UKA knee (n.s.). CONCLUSIONS:For both the Lachman test and the pivot shift test, single-bundle ACL reconstruction restored kinematics in the UKA knee to magnitudes similar to those in the ACL-intact knee. 10.1007/s00167-011-1449-5
    Unicompartmental knee arthroplasty versus total knee arthroplasty: Which type of artificial joint do patients forget? Zuiderbaan Hendrik A,van der List Jelle P,Khamaisy Saker,Nawabi Danyal H,Thein Ran,Ishmael C,Paul Sophia,Pearle Andrew D Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:During recent years, there has been an intensive growth of interest in the patient's perception of functional outcome. The Forgotten Joint Score (FJS) is a recently introduced score that measures joint awareness of patients who have undergone knee arthroplasty and is less limited by ceiling effects. The aim of this study was to compare the FJS between patients who undergo medial unicompartmental knee arthroplasty (UKA) and patients who undergo total knee arthroplasty (TKA) 1 and 2 years post-operatively. METHODS:This prospective study compares the FJS at a minimum of one (average 1.5 years, range 1.0-1.9) and a minimum of 2 years (average 2.5 years, range 2.0-3.6) post-operatively between patients who underwent medial UKA and TKA. RESULTS:One-hundred and thirty patients were included. Sixty-five patients underwent medial UKA and 65 patients underwent TKA. At both follow-up points, the FJS was significantly higher in the UKA group (FJS 1 year 73.9 ± 22.8, FJS 2 year 74.3 ± 24.8) in contrast to the TKA group (FJS 1 year 59.3 ± 29.5 (p = 0.002), FJS 2 year 59.8 ± 31.5, (p = 0.004)). No significant improvement in the FJS was observed between 1- and 2-year follow-up of the two cohorts. CONCLUSION:Patients who undergo UKA are more likely to forget their artificial joint in daily life and consequently may be more satisfied. LEVEL OF EVIDENCE:II. 10.1007/s00167-015-3868-1
    Weight-bearing status affects in vivo kinematics following mobile-bearing unicompartmental knee arthroplasty. Kono Kenichi,Inui Hiroshi,Tomita Tetsuya,Yamazaki Takaharu,Taketomi Shuji,Yamagami Ryota,Kawaguchi Kohei,Sugamoto Kazuomi,Tanaka Sakae Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The effects of weight bearing (WB) on knee kinematics following mobile-bearing unicompartmental knee arthroplasty (UKA) remain unknown. The purpose of this study was to clarify the effects of WB on in vivo kinematics of mobile-bearing UKA during high knee flexion activities. METHODS:The kinematics of UKA were evaluated under fluoroscopy during squatting (WB) and active-assisted knee flexion (non-weight bearing, NWB). Range of motion, femoral axis rotation relative to the tibia, anteroposterior (AP) translation of the medial and lateral sides, and kinematic pathway were measured. RESULTS:There were no differences in knee flexion range and external rotation of the femur in each flexion angle between the WB conditions. The amount of femoral external rotation between minimum flexion and 60° of flexion during WB was significantly larger than that during NWB, and that between 60° and 130° of flexion during NWB was significantly larger than that during WB. There were no differences in medial AP translation of the femur in each flexion angle between the WB conditions. However, on the lateral side, posterior translation of 52.9 ± 12.7% was observed between minimum flexion and 130° of flexion during WB. During NWB, there was no significant translation between minimum flexion and 60° of flexion; beyond 60° of flexion, posterior translation was 41.6 ± 8.7%. Between 20° and 80° of flexion, the lateral side in WB was located more posteriorly than in NWB (p < 0.05). CONCLUSION:Mobile-bearing UKA has good anterior stability throughout the range of knee flexion. WB status affects the in vivo kinematics following mobile-bearing UKA. LEVEL OF EVIDENCE:III. 10.1007/s00167-020-05893-x
    In vitro kinematics of fixed versus mobile bearing in unicondylar knee arthroplasty. Ettinger Max,Zoch Johanna Marie,Becher Christoph,Hurschler Christof,Stukenborg-Colsman Christina,Claassen Leif,Ostermeier Sven,Calliess Tilman Archives of orthopaedic and trauma surgery PURPOSE:When performing unicondylar knee arthroplasty (UKA), the surgeon can choose between two fundamentally different designs: a mobile-bearing (MB) inlay with high conformity, or a low-conformity, fixed bearing (FB) inlay. There is an ongoing debate in the orthopaedic community about which design is superior. To date, there have been no comparative biomechanical studies regarding each system's effects on the quadriceps force and the medial contact pressure. The purpose of this study was to investigate these alterations in vitro before and after UKA with two prosthesis systems, representing the MB and FB designs. METHODS:FB and MB unicondylar knee prosthesis designs were tested in sequence under isokinetic extension in an in vitro simulator. In each case, the required quadriceps extension force was determined before and after implantation of a medial UKA. Furthermore, the tibiofemoral contact pressures were evaluated for both prosthesis designs. RESULTS:The quadriceps force maximum was achieved at 106° and 104° of flexion with the FB and MB designs, respectively. Implantation of the FB UKA resulted in a significant increase in the necessary maximum quadriceps force (p = 0.006). In addition, implantation of the MB UKA resulted in a significantly higher extension force (p = 0.03). The difference between the two groups was statistically significant in deep flexion (p = 0.03), with higher forces in MB UKA. CONCLUSION:The MB design showed significantly increased quadriceps extension force compared with the FB inlay in deep flexion. Although the FB design showed higher maximum peak pressures concentrated on a smaller area, the pressure introduction in deep flexion was lower, compared to MB inserts. 10.1007/s00402-015-2214-x
    Outcomes After Arthroscopic Evaluation of Patients With Painful Medial Unicompartmental Knee Arthroplasty. Hurst Jason M,Ranieri Riccardo,Berend Keith R,Morris Michael J,Adams Joanne B,Lombardi Adolph V The Journal of arthroplasty BACKGROUND:Persistent pain after medial unicompartmental knee arthroplasty (UKA) is a prevailing reason for revision to total knee arthroplasty (TKA). Many of these pathologies can be addressed arthroscopically. The purpose of this study is to examine the outcomes of patients who undergo an arthroscopy for any reason after medial UKA. METHODS:A query of our practice registry revealed 58 patients who had undergone medial UKA between October 2003 and June 2015 with subsequent arthroscopy. Mean interval from medial UKA to arthroscopy was 22 months (range 1-101 months). Indications for arthroscopy were acute anterior cruciate ligament tear (1), arthrofibrosis (7), synovitis (12), recurrent hemarthrosis (2), lateral compartment degeneration including isolated lateral meniscus tears (11), and loose cement fragments (25). RESULTS:Mean follow-up after arthroscopy was 49 months (range 1-143 months). Twelve patients have been revised from UKA to TKA. Relative risk of revision after arthroscopy for lateral compartment degeneration was 4.27 (6 of 11; 55%; P = .002) and for retrieval of loose cement fragments was 0.05 (0 of 25; 0%; P = .03). Relative risk for revision after arthroscopy for anterior cruciate ligament tear, arthrofibrosis, synovitis, or recurrent hemarthrosis did not meet clinical significance secondary to the low number of patients in these categories. CONCLUSION:The results of this study suggest that arthroscopic retrieval of cement fragments does not compromise UKA longevity. However, arthroscopy for lateral compartment degradation after UKA, while not the cause of revision, appears to be an ineffective treatment and predicts a high risk of revision to TKA regardless of its relative radiographic insignificance. 10.1016/j.arth.2018.05.031
    Gait comparison of unicompartmental and total knee arthroplasties with healthy controls. Jones G G,Kotti M,Wiik A V,Collins R,Brevadt M J,Strachan R K,Cobb J P The bone & joint journal AIMS:To compare the gait of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) patients with healthy controls, using a machine-learning approach. PATIENTS AND METHODS:145 participants (121 healthy controls, 12 patients with cruciate-retaining TKA, and 12 with mobile-bearing medial UKA) were recruited. The TKA and UKA patients were a minimum of 12 months post-operative, and matched for pattern and severity of arthrosis, age, and body mass index. Participants walked on an instrumented treadmill until their maximum walking speed was reached. Temporospatial gait parameters, and vertical ground reaction force data, were captured at each speed. Oxford knee scores (OKS) were also collected. An ensemble of trees algorithm was used to analyse the data: 27 gait variables were used to train classification trees for each speed, with a binary output prediction of whether these variables were derived from a UKA or TKA patient. Healthy control gait data was then tested by the decision trees at each speed and a final classification (UKA or TKA) reached for each subject in a majority voting manner over all gait cycles and speeds. Top walking speed was also recorded. RESULTS:92% of the healthy controls were classified by the decision tree as a UKA, 5% as a TKA, and 3% were unclassified. There was no significant difference in OKS between the UKA and TKA patients (p = 0.077). Top walking speed in TKA patients (1.6 m/s; 1.3 to 2.1) was significantly lower than that of both the UKA group (2.2 m/s; 1.8 to 2.7) and healthy controls (2.2 m/s; 1.5 to 2.7; p < 0.001). CONCLUSION:UKA results in a more physiological gait compared with TKA, and a higher top walking speed. This difference in function was not detected by the OKS. Cite this article: Bone Joint J 2016;98-B(10 Suppl B):16-21. 10.1302/0301-620X.98B10.BJJ.2016.0473.R1
    Outcome of Unicondylar Knee Arthroplasty vs Total Knee Arthroplasty for Early Medial Compartment Arthritis: A Randomized Study. Kulshrestha Vikas,Datta Barun,Kumar Santhosh,Mittal Gaurav The Journal of arthroplasty BACKGROUND:With increasing number of patients with early osteoarthritis of knee opting for total knee arthroplasty (TKA), there has been increase in patients dissatisfied with surgical outcomes. It is being presumed that offering unicondylar knee arthroplasty (UKA) to them would improve outcomes. METHODS:Primary objective of our study was to look for any difference in patient-reported outcome and function at 2-year follow-up in patients undergoing UKA as compared to TKA. Our study was a randomized study with parallel assignment conducted at a high-volume specialized arthroplasty center. Eighty patients with bilateral isolated medial compartment knee arthritis were randomized into simultaneous 2-team bilateral TKA (n = 40) and UKA (n = 40) group. We finally analyzed 36 patients in each group. Main outcome measure was improvement in Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS) and High Activity Arthroplasty Score (HAAS) obtained at 2-year follow-up. RESULTS:Improvement in KOS-ADLS and HAAS at 2 years was similar (P = .2143 and .2010) in both groups. Performance as assessed with Delaware index was also similar. Length of hospital stay was less in UKA group (6.6 days as against 5.4 days). Complications and readmission rates were more in TKA group (nil in UKA group; 08 in TKA group). CONCLUSION:At 2-year follow-up, UKA provides similar improvement in patient-reported outcomes, function, and performance as compared to TKA when performed in patients with early arthritis. However, UKA patients have shorter hospital stay and fewer complications. 10.1016/j.arth.2016.12.014
    Unicompartmental Knee Arthroplasty in Patients Older Than 75 Results in Better Clinical Outcomes and Similar Survivorship Compared to Total Knee Arthroplasty. A Matched Controlled Study. Fabre-Aubrespy Maxime,Ollivier Matthieu,Pesenti Sébastien,Parratte Sébastien,Argenson Jean-Noël The Journal of arthroplasty BACKGROUND:Due to the potential reduction of morbidity and mortality, unicompartmental knee arthroplasty (UKA) may represent an interesting solution for older patients with unicompartmental arthritis. It was our hypothesis that UKA can represent an alternative to total knee arthroplasty (TKA) for patients older than 75. We, thus, aimed to compare in those patients (1) functional results, (2) rates of forgotten joint, and (3) survivorships of UKA vs TKA. METHODS:In this retrospective matched-pair study, 101 patients who underwent UKA in our institution were included and then matched one-to-one with TKA group based on age, gender, body mass index, preoperative Knee Society Score (KSS). Inclusion criteria were age between 75 and 90 years on the day of surgery, knee arthroplasty performed for primary osteoarthritis or osteonecrosis of the knee. All patients were evaluated clinically (using KSS, Knee Injury Osteoarthritis Outcome Score [KOOS], and Forgotten Joint Score) at 1, 2, and every 5 years, thereafter. Survivorships of UKA and TKA implants were also compared. RESULTS:At last follow-up, patients from UKA group had better KSS than in TKA group, (respectively, KSS function 82.8 ± 12.2 vs 79.2 ± 13.1 [P = .0448] and KSS knee 88.2 ± 8.9 vs 82.3 ± 12.5 [P = .0005]). Knee Injury Osteoarthritis Outcome Scores were also higher in UKA group (all P < .001) as well as the rate of forgotten knees (42% vs 25% P = .01). Sixteen-year survivorships free from revision for any reason were similar in the 2 groups (91.8% vs 94.6% P = .66). CONCLUSION:The results of our study showed that UKA provide higher function and better forgotten joint scores with similar survivorship, compared to TKA, for patients older than 75. 10.1016/j.arth.2016.06.034
    Patients with isolated lateral osteoarthritis: Unicompartmental or total knee arthroplasty? van der List J P,Chawla H,Zuiderbaan H A,Pearle A D The Knee BACKGROUND:Lateral unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are both reliable treatment options for patients with isolated lateral osteoarthritis (OA). However, studies comparing both procedures are scarce. Aims of this study were to (I) compare short-term functional outcomes following lateral UKA and TKA and (II) assess the role of patient characteristics on outcomes as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). METHODS:In this retrospective cohort study, 82 patients (48 undergoing lateral UKA and 34 undergoing TKA) were identified that presented with lateral OA and completed the WOMAC. Independent t-tests were used to compare outcomes following lateral UKA and TKA. RESULTS:Mean follow-up was 2.8 years (range: 2.0 - 5.0 years). Preoperatively, no differences between lateral UKA and TKA were seen (50.1±13.5 and 53.3±17.1, respectively, p=0.551). Postoperatively, lateral UKA patients reported better overall outcomes than TKA (90.5±11.7 vs. 81.8±17.9, p=0.017). Subgroup analysis showed better outcomes following lateral UKA than TKA in patients younger than 75 years (92.1±9.9 vs. 81.3±19.6, p=0.014) and in females (91.6±9.9 vs. 81.0±18.2, p=0.014). CONCLUSION:These findings indicate that lateral UKA has superior short-term functional outcomes compared to TKA in patients with isolated lateral OA. Better outcomes were especially seen in younger patients and females. These findings may help orthopedic surgeons choose treatment for patients presenting with lateral OA and optimize treatment for individual patients. 10.1016/j.knee.2016.06.007
    Comparison of clinical outcomes between total knee arthroplasty and unicompartmental knee arthroplasty for osteoarthritis of the knee: a retrospective analysis of preoperative and postoperative results. Horikawa Akira,Miyakoshi Naohisa,Shimada Yoichi,Kodama Hiroyuki Journal of orthopaedic surgery and research BACKGROUND:Excellent results have recently been reported for both total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), but there have been few reports about which has a better long-term outcome. The preoperative and postoperative results of TKA and UKA for osteoarthritis of the knee were thus compared. METHODS:The results of 48 patients who underwent TKA and 25 patients who underwent UKA were evaluated based on clinical scores and survivorship in the middle long-term period. Preoperative, latest postoperative, and changes in the femoro-tibial angle (FTA), range of motion (ROM), Japanese Orthopedic Association score (JOA score), and Japanese Knee Osteoarthritis Measure (JKOM) were compared. The patients' mean age was 73 years. The mean follow-up period was 9 years (TKA: mean, 10.5 years; range, 7-12 years; UKA: mean, 9 years; range, 6-11 years). RESULTS:Preoperative FTA and ROM were significantly higher in the UKA group than in the TKA group. Total changes in all scores were similar among the two groups, as were changes in scores for all JOA and JKOM domains. The cumulative revision rate was higher for UKA than for TKA (7 versus 4%). Kaplan-Meier survivorship at 10 years was 84% for UKA and 92% for TKA. CONCLUSIONS:This clinical study found no significant differences between TKA and UKA, except in long-term survivorship. 10.1186/s13018-015-0309-2
    Open wedge high tibial osteotomy (HTO) versus mobile bearing unicondylar medial joint replacement: five years results. Petersen Wolf,Metzlaff Sebastian Archives of orthopaedic and trauma surgery INTRODUCTION:Aim of this study was to compare clinical results after open wedge HTO (OW-HTO and medial unicondylar joint replacement (UKA) in patients aged between 55 and 65. MATERIALS AND METHODS:Fifty-four patients aged between 55 and 65 years with medial OA and varus malalignement who had been treated by either OW-HTO or UKA could be included. Minimum follow up was 5 years. The HSS knee score and the KOOS were used to evaluate clinical outcome. RESULTS:There was no difference in the revision rate, the HSS knee score and the KOOS subscales Sports/Rec and ADL between the OW-HTO and UKA group. However, the KOOS subscales pain, Symptoms and QoL were significantly better in the UKA group compared to the OW-HTO. CONCLUSIONS:The results of this study showed that 5 years after surgery patients after UKA had less residual pain and symptoms than patients after UKA. These advantages might result in a higher quality of life. 10.1007/s00402-016-2465-1
    Obesity, morbid obesity and their related medical comorbidities are associated with increased complications and revision rates after unicompartmental knee arthroplasty. Kandil Abdurrahman,Werner Brian C,Gwathmey Winston F,Browne James A The Journal of arthroplasty Recent studies have demonstrated clinical success in expanding the indications for unicompartmental knee arthroplasty (UKA) to patients with increased body mass index (BMI). This study utilized national databases to identify 15,770 unique patients who underwent UKA between 2005 and 2011. 18.7% of patients undergoing a UKA were obese or morbidly obese. Univariate analysis demonstrated that obesity and morbid obesity were associated with significantly higher complication rates within 90 days postoperatively compared to non-obese patients. The overall short-term revision rate in obese and morbidly obese patients undergoing UKA was almost twice as high as the revision rate in non-obese patients. Obese and morbidly obese patients being considered for UKA should be counseled preoperatively regarding their increased risk of postoperative complications and revision surgery. 10.1016/j.arth.2014.10.016
    Lower limb kinematics of unicompartmental knee arthroplasty individuals during stair ascent. Kakar Rumit Singh,Fu Yang-Chieh,Kinsey Tracy L,Brown Cathleen N,Mahoney Ormonde M,Simpson Kathy J Journal of orthopaedics Objective:Purpose of the study was to compare lower-limb kinematics and interlimb asymmetry during stair ascent in individuals post-medial or lateral unicompartmental knee arthroplasty (UKA). Methods:60 patients (20 medial; 10 lateral) post-UKA and 30 matched healthy controls performed stair ascent. Spatio-temporal, lower-limb kinematics and interlimb asymmetries during stair ascent were compared. Results:Medial-UKA group displayed 5° less knee extension of the UKA limb than controls (p = 0.005) and 2° less than the contralateral limb during stance phase. No interlimb asymmetries were found for lateral-UKA. Conclusion:Patients post-UKA demonstrate satisfactory lower-limb kinematics and minimal interlimb asymmetry during stair ascent compared to healthy individuals. 10.1016/j.jor.2020.04.009
    Return to Sports and Physical Activity After Total and Unicondylar Knee Arthroplasty: A Systematic Review and Meta-Analysis. Witjes Suzanne,Gouttebarge Vincent,Kuijer P Paul F M,van Geenen Rutger C I,Poolman Rudolf W,Kerkhoffs Gino M M J Sports medicine (Auckland, N.Z.) BACKGROUND:People today are living longer and want to remain active. While obesity is becoming an epidemic, the number of patients suffering from osteoarthritis (OA) is expected to grow exponentially in the coming decades. Patients with OA of the knee are progressively being restricted in their activities. Since a knee arthroplasty (KA) is a well accepted, cost-effective intervention to relieve pain, restore function and improve health-related quality of life, indications are expanding to younger and more active patients. However, evidence concerning return to sports (RTS) and physical activity (PA) after KA is sparse. OBJECTIVES:Our aim was to systematically summarise the available literature concerning the extent to which patients can RTS and be physically active after total (TKA) and unicondylar knee arthroplasty (UKA), as well as the time it takes. METHODS:PRISMA guidelines were followed and our study protocol was published online at PROSPERO under registration number CRD42014009370. Based on the keywords (and synonyms of) 'arthroplasty', 'sports' and 'recovery of function', the databases MEDLINE, Embase and SPORTDiscus up to January 5, 2015 were searched. Articles concerning TKA or UKA patients who recovered their sporting capacity, or intended to, were included and were rated by outcomes of our interest. Methodological quality was assessed using Quality in Prognosis Studies (QUIPS) and data extraction was performed using a standardised extraction form, both conducted by two independent investigators. RESULTS:Out of 1115 hits, 18 original studies were included. According to QUIPS, three studies had a low risk of bias. Overall RTS varied from 36 to 89% after TKA and from 75 to >100% after UKA. The meta-analysis revealed that participation in sports seems more likely after UKA than after TKA, with mean numbers of sports per patient postoperatively of 1.1-4.6 after UKA and 0.2-1.0 after TKA. PA level was higher after UKA than after TKA, but a trend towards lower-impact sports was shown after both TKA and UKA. Mean time to RTS after TKA and UKA was 13 and 12 weeks, respectively, concerning low-impact types of sports in more than 90 % of cases. CONCLUSIONS:Low- and higher-impact sports after both TKA and UKA are possible, but it is clear that more patients RTS (including higher-impact types of sports) after UKA than after TKA. However, the overall quality of included studies was limited, mainly because confounding factors were inadequately taken into account in most studies. 10.1007/s40279-015-0421-9
    Early comparative outcomes of unicompartmental and total knee arthroplasty in severely obese patients. Lum Zachary C,Crawford David A,Lombardi Adolph V,Hurst Jason M,Morris Michael J,Adams Joanne B,Berend Keith R The Knee BACKGROUND:Medial unicompartmental knee arthroplasty (UKA) may have advantages over total knee arthroplasty (TKA) in the setting of obesity. There has been no direct comparison between the two cohorts. This study compares outcomes and complications of severely obese patients undergoing medial UKA versus TKA. METHODS:Six hundred and fifty medial UKA and 1300 TKA were performed in patients with BMI >35kg/m (mean 41kg/m) between 2007 and 2012. Pre- and postoperative ROM, Knee Society scores, perioperative factors, complications and reoperations were compared. RESULTS:UKA patients had higher preoperative ROM, and Knee Society pain (KSP), functional (KSF), and clinical (KSC) scores (p<0.001, p=0.0008, p=0.0003, p=0.051 respectively). Mean tourniquet times, operative times, and lengths of stay were lower after UKA. Four TKA patients required transfusion. Mean follow-up was 2.3years. The frequency of manipulation under anesthesia was higher in TKA patients (p<0.001), while the rate of component revision was similar between the two groups (1.2% vs. 1.7%, p=0.328). Frequency of deep infection was lower in the UKA group (p=0.016). Postoperative KSF, change in KSF, and ROM were higher (p<0.0001) after UKA, but KSP and KSC were equivalent. CONCLUSIONS:Severely obese patients who underwent medial UKA demonstrated equal survivorship with substantially fewer reoperations, reduced deep infection, and less perioperative complications at short term follow-up. Severely obese patients had improved KSF scores and maintenance of ROM after UKA compared with TKA. 10.1016/j.knee.2017.10.006
    [Research progress in unicompartmental knee arthroplasty]. Wu Dong,Yang Minzhi,Cao Zheng,Kong Xiangpeng,Wang Yi,Guo Renwen,Chai Wei Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery Objective:To summarize the clinical application and research progress in unicompartmental knee arthroplasty (UKA). Methods:The literature related to UKA in recent years was reviewed and the emerging indications, implant options, comparisons between other surgical techniques, and recent advances were summarized. Results:Clinical studies show that UKA has many advantages, such as less trauma, faster recovery, and fewer postoperative complications. At present, the operative indication has been expanded. The body mass index more than 25 kg/m , less than 60 years old, patellofemoral arthritis, and anterior cruciate ligament dysfunction are no longer considered as contraindications. The prosthesis type in UKA should be selected according to the patient's condition. In recent years, the robot-assisted UKA can effectively improve the effectiveness, improve patient satisfaction, and reduce postoperative complications. Conclusion:With the development of surgical techniques, designs of prosthesis, and the robotic technology, UKA would be further applicated. As more long-term data on UKA become available, it will further guide clinicians in counseling patients on whether UKA should be performed. 10.7507/1002-1892.201906085
    Systematic review of medial versus lateral survivorship in unicompartmental knee arthroplasty. van der List J P,McDonald L S,Pearle A D The Knee BACKGROUND:Unicompartmental knee arthroplasty (UKA) has gained popularity in patients with isolated unicompartmental osteoarthritis. To our knowledge no systematic review has assessed and compared survivorship of medial and lateral UKA. We performed a systematic review assessing medial and lateral UKA survivorship and comparing survivorship in cohort studies and registry-based studies. METHODS:A search was performed using PubMed, Embase and Cochrane systems. Ninety-six eligible studies reported survivorship, of which fifty-eight reported medial and sixteen reported lateral UKA survivorship. Nineteen cohort studies and seven registry-based studies reported combined medial and lateral survivorship. RESULTS:The five-year, ten-year and fifteen-year medial UKA survivorship was 93.9%, 91.7% and 88.9%, respectively. Lateral UKA survivorship was 93.2%, 91.4% and 89.4% at five-year, ten-year and fifteen-year, respectively. No statistical difference between both compartments was found. At twenty years and twenty-five years survivorship of medial UKA was 84.7% and 80%, respectively, but no studies reported lateral UKA survivorship at these follow-up intervals. Survivorship of cohort studies was not significantly higher compared to registry-based studies at five years (94.3 vs. 91.7, respectively, p=0.133) but was significantly higher at ten years (90.5 vs. 84.1, p=0.015). CONCLUSION:This is the first systematic review that shows no difference in the five-, ten- and fifteen-year survivorship of medial and lateral UKA. We found a lower survivorship in the registry-based studies compared to cohort studies. 10.1016/j.knee.2015.09.011
    Effect of Computer Navigation on Complication Rates Following Unicompartmental Knee Arthroplasty. Chona Deepak,Bala Abiram,Huddleston James I,Goodman Stuart B,Maloney William J,Amanatullah Derek F The Journal of arthroplasty BACKGROUND:We evaluated whether the complication and revision rates of unicompartmental knee arthroplasty (UKA) performed with intraoperative computer-based navigation differ from standard UKAs performed without intraoperative computer-based navigation. METHODS:A Medicare database containing administrative claims data from 2005 to 2014 was queried. Patients who underwent a single UKA and had a minimum of 2 years of follow-up were included in the study. Data from 1025 UKAs performed with navigation were compared against 9228 age and gender-matched UKAs performed without it. Postoperative complications were identified using International Classification of Diseases, Ninth Revision, codes and evaluated at 30 days, 90 days, and 2 years. RESULTS:Orthopedic complications after UKA are rare, and the use of navigation did not affect the rate of conversion to total knee arthroplasty at 2-year follow-up (3.8% in navigated UKAs vs 4.7% in standard UKAs, P = .218). There were also no significant differences in the rates of knee arthrotomy at 2-year follow-up (1.3% in navigated UKAs vs 1.6% in standard UKAs, P = .379). The rates of deep vein thrombosis at 90-day follow-up did not significantly differ between the 2 groups (1.4% in navigated UKAs vs 2.0% in standard UKAs, P = .157). CONCLUSION:This is one of the first studies to use a large cohort to compare outcomes in computer-assisted surgery-UKA against standard UKAs without navigation. The results, particularly that there was not a difference in the rate of conversion to total knee arthroplasty, are directly relevant to clinical decision-making when surgeons are considering employing navigation during UKA. 10.1016/j.arth.2018.06.030
    Differences in Patient-Reported Outcomes Between Unicompartmental and Total Knee Arthroplasties: A Propensity Score-Matched Analysis. Kim Man S,Koh In J,Choi Young J,Lee Jong Y,In Yong The Journal of arthroplasty BACKGROUND:The purpose of this study was to compare the patient-reported outcomes regarding joint awareness, function, and satisfaction after unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). METHODS:We identified all patients who underwent a UKA or TKA at our institution between September 2011 and March 2014, with a minimum follow-up of 2 years. Propensity score matching was performed for age, gender, body mass index, operation side, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. One hundred UKAs to 100 TKAs were matched. Each knee was evaluated according to the WOMAC score, Forgotten Joint Score (FJS), High Flexion Knee Score (HFKS) and patient's satisfaction at postoperative 2 years. RESULTS:There was no significant difference in WOMAC score at postoperative 2 years between UKA and TKA groups. However, the FJS of the UKA group was significantly higher than that of the TKA group (67.3 ± 19.8 and 60.6 ± 16.6, respectively; P = .011). The HFKS was also significantly higher in the UKA group compared with the TKA group (34.4 ± 6.4 and 31.3 ± 5.2, respectively; P < .001). Eighty-six percent of all patients who underwent UKA were satisfied compared with 71% of those who underwent TKA (P = .027). CONCLUSION:Patients who underwent UKA had higher FJS, HFKS, and satisfaction rate when compared with patients who underwent TKA, indicating that UKA facilitated less knee awareness and better function and satisfaction than TKA. 10.1016/j.arth.2016.11.034
    Lateral unicompartmental knee replacement for the treatment of arthritis progression after medial unicompartmental replacement. Pandit H,Mancuso F,Jenkins C,Jackson W F M,Price A J,Dodd C A F,Murray D W Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Lateral progression of arthritis following medial unicompartmental knee arthroplasty (UKA), although infrequent, is still the most common reason for revision surgery. Treatment options normally include conversion to total knee arthroplasty. An alternative strategy for some patients may be addition of a lateral UKA. We report the first results of staged bi-compartmental UKA (Bi-UKA) strategy. METHODS:We retrospectively selected from our UKA database patients who underwent a lateral UKA to treat a symptomatic lateral osteoarthritis progression after a medial UKA. The analysis included a clinical and radiological assessment of each patient. RESULTS:Twenty-five patients for a total of 27 knees of staged Bi-UKA were carried out in a single centre. The mean time interval between primary medial UKA and the subsequent lateral UKA was 8.1 years (SD ± 4.6 years). The mean age at the time of the Bi-UKA was 77.1 years (SD ± 6.5 years). The median hospital stay was 3 (range 2-9 days) days, and the mean follow-up after Bi-UKA was 4 years (SD ± 1.9 years). The functional scores showed a significant improvement as compared to the pre-operative status (paired t test, p = 0.003). There were no radiological evidences of failure. None of the patients needed blood transfusion, and there was no significant complications related to the surgical procedure without further surgeries or revisions at final follow-up. CONCLUSIONS:These results suggest that addition of a lateral UKA for arthritis progression following medial UKA is a good option in appropriately selected patients. LEVEL OF EVIDENCE:Observational study without controls, Level IV. 10.1007/s00167-016-4075-4
    Unicompartmental Knee Arthroplasty vs Total Knee Arthroplasty for Medial Compartment Arthritis in Patients Older Than 75 Years: Comparable Reoperation, Revision, and Complication Rates. Siman Homayoun,Kamath Atul F,Carrillo Nazly,Harmsen William S,Pagnano Mark W,Sierra Rafael J The Journal of arthroplasty BACKGROUND:Prior studies comparing unicompartmental knee arthroplasty (UKA) with total knee arthroplasty (TKA) in the elderly are limited by heterogeneity in arthritic disease patterns and patient selection. We report the results of UKA and TKA in patients 75 years and older with isolated medial compartmental arthritis, with special emphasis on immediate postoperative recovery, complications, reoperation rates, and implant survivorship at midterm follow-up. METHODS:A retrospective review was performed of all patients 75 years and older who underwent UKA or TKA at our institution between 2002 and 2012. All TKA preoperative X-rays were reviewed by a blind observer to identify knees with isolated medial compartmental arthritis considered acceptable candidates for UKA. Patients with less than 2 years of follow-up, flexion contracture greater than 10°, and rheumatoid arthritis were excluded. The final sample included 120 UKA (106 patients) and 188 TKA (170 patients) procedures. Patient records were reviewed to determine early postoperative recovery, complications, reoperations for any reason, and implant survivorship. RESULTS:UKA patients experienced significantly shorter operative time, shorter hospital stay, lower intraoperative estimated blood loss, lower postoperative transfusions, greater postoperative range of motion, and higher level of activity at time of discharge. Two UKA and 2 TKA patients required revision surgery. There was no statistically significant difference in postoperative Knee Society Scores. There were no differences in 5-year survivorship estimates. CONCLUSION:Due to its less invasive nature, patients older than 75 undergoing UKA demonstrated faster initial recovery when compared to TKA, while maintaining comparable complications and midterm survivorship. UKA should be offered as an option in the elderly patient who fits the selection criteria for UKA. 10.1016/j.arth.2017.01.020
    Faster return to sport after robotic-assisted lateral unicompartmental knee arthroplasty: a comparative study. Canetti R,Batailler C,Bankhead C,Neyret P,Servien E,Lustig S Archives of orthopaedic and trauma surgery INTRODUCTION:Unicompartmental knee arthroplasty (UKA) is frequently performed on active patients with symptomatic osteoarthritis who desire a quick return to sports. The aim of this study was to compare return to sport after lateral UKA performed by robotic-assisted and conventional techniques. MATERIALS AND METHODS:This retrospective study has assessed 28 lateral UKA (25 patients), 11 performed with robotic-assisted technique and 17 with conventional technique, between 2012 and 2016. The mean age was 65.5 and 59.5 years, with a mean follow-up of 34.4 months (range 15-50) and 39.3 months (range 22-68). Both groups were comparable pre-operatively. Sport habits and the details of the return to sports were assessed using University of California, Los Angeles Scale (UCLA) and direct questioning. RESULTS:Robotic-assisted surgical technique provided significantly quicker return to sports than conventional technique (4.2 ±1.8 months; range 1-6 vs 10.5 ± 6.7 months; range 3-24; p < 0.01), with a comparable rate of return to sports (100% vs 94%). The practiced sports after lateral UKA were similar to those done preoperatively, with mainly low- and mid-impact sports (hiking, cycling, swimming, and skiing). CONCLUSION:Robotic-assisted lateral UKA reduces the time to return to sports at pre-symptomatic levels when compared with conventional surgical technique. The return to sports rate after surgery is high in both groups. A long-term study would provide data on the prothesis wear in this active population. LEVEL OF EVIDENCE:Comparative retrospective study, Level III. 10.1007/s00402-018-3042-6
    Robotic-assisted Medial Unicompartmental Knee Arthroplasty: Options and Outcomes. Lonner Jess H,Klement Mitchell R The Journal of the American Academy of Orthopaedic Surgeons Medial unicompartmental knee arthroplasty (UKA) has several benefits over total knee arthroplasty for the surgical treatment of isolated medial compartmental arthritis in the knee, including reduced surgical risk and postoperative morbidity, rapid recovery, more normal kinematics, greater patient satisfaction, and shorter hospitalization. Nonetheless, there is substantial concern about the higher revision rates and lower survivorship in UKA compared to those in total knee arthroplasty. Robotic assistance has been advanced to improve the precision of bone preparation, component alignment, and quantified ligament balance in UKA, with the ultimate goal of improving kinematics and implant survivorship. Two currently available semiautonomous robotic platforms have demonstrated improved accuracy, and emerging short-term follow-up has demonstrated satisfactory functional outcomes. Further studies will be needed to determine if these technologies indeed have a meaningful impact on patient outcomes and survivorship in the mid- to long term. 10.5435/JAAOS-D-17-00710
    Pros and Cons: A Balanced View of Robotics in Knee Arthroplasty. Lonner Jess H,Fillingham Yale A The Journal of arthroplasty In both unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA), compared with conventional techniques robotic technology has been shown to optimize the precision of bone preparation and component alignment, reducing outliers and increasing the percentage of components aligned within 2° or 3° of the target goal. In addition, soft tissue balance can be quantified through a range of motion in UKA and TKA using the various robotic technologies available. Although the presumption has been that the improved alignment associated with robotics will improve function and implant durability, there are limited data to support that notion. Based on recent and emerging data, it may be unreasonable to presume that robotics is necessary for both UKA and TKA. In fact, despite improvements in various proxy measures, the precision of robotics may be more important for UKA than TKA, although if system costs and surgical efficiencies continue to improve, streamlining perioperative processes, reducing instrument inventory, and achieving comparable outcomes in TKA may be a reasonable goal of robotic surgery. 10.1016/j.arth.2018.03.056
    Prior high tibial osteotomy is not a contraindication for medial unicompartmental knee arthroplasty. Schlumberger Michael,Oremek Damian,Brielmaier Moritz,Buntenbroich Uli,Schuster Philipp,Fink Bernd Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:To report on the outcome and complications of minimal invasive medial unicondylar knee arthroplasty (UKA) after failed prior high tibial osteotomy (HTO) as treatment for medial osteoarthritis in the knee. The hypothesis was that good results can be achieved, if no excessive postoperative valgus alignment and abnormal proximal tibial geometry is present. METHODS:All medial UKAs after failed prior HTO (n = 30), performed between 2010 and 2018 were retrospectively reviewed. The patients were followed for revision surgery and survival of the UKA (defined as revision to TKA). Clinical examination using the Knee Society Score (KSS), Oxford Knee Score (OKS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), as well as radiological examination was performed. Radiographs were studied and the influence of the demographic factors and the radiographic measurements on the survival and the clinical outcome was analysed. RESULTS:After a follow-up of 4.3 ± 2.6 years (2.1-9.9) 27 UKAs were available. The survival rate was 93.0%. Two UKAs were revised to TKA (excessive valgus alignment and tibial loosening with femoropatellar degeneration). Two further patients had revision surgery (hematoma and lateral meniscus tear). Follow-up clinical and radiological examination was performed in 21 cases: KSS 82.9 ± 10.1 (54.0-100.0), KSS (function) 93.3 ± 9.7 (70.0-100.0); OKS 42.7 ± 6.0 (25.0-48.0); WOMAC 7.9 ± 15.6 (0.0-67.1). No significant influence of demographic factors or radiological measurements on the clinical outcome was present. CONCLUSION:Prior HTO is not a contraindication for medial UKA, because good-to-excellent results can be achieved in selected patients with medial osteoarthritis and previous HTO, treated with medial UKA, in a midterm follow-up. Excessive mechanical valgus axis should be avoided; therefore, patient selection and accurate evaluation of medial laxity, preoperative mechanical axis, joint line convergence and proximal tibial geometry are important. LEVEL OF EVIDENCE:III. 10.1007/s00167-020-06149-4
    Gait comparison of unicompartmental knee arthroplasty and total knee arthroplasty during level walking. Nha Kyung-Wook,Shon Oog-Jin,Kong Byung-Sic,Shin Young-Soo PloS one This meta-analysis compared the gait patterns of unicompartmental knee arthroplasty (UKA) patients and total knee arthroplasty (TKA) patients during level walking by evaluating the kinetics, kinematics, and spatiotemporal parameters. Studies were included in the meta-analysis if they assessed the vertical ground reaction force (GRF), joint moment at stance, flexion at initial contact, flexion at swing, overall range of motion (ROM), coronal knee angle at stance, walking speed, cadence, and stride length in UKA patients or TKA patients. Seven non-randomized studies met the criteria for inclusion in this meta-analysis. UKA patients and TKA patients were similar in terms of vertical GRF (95% CI: -0.36 to 0.20; P = 0.60), joint moment (95% CI: -0.55 to 0.63; P = 0.90), kinematic outcomes (95% CI: -0.72 to 1.02; P = 0.74), walking speed (95% CI: -0.27 to 0.81; P = 0.32), and cadence (95% CI: -0.14 to 0.68; P = 0.20). In contrast, the stride length (95% CI: 0.01 to 0.80; P = 0.04) differed significantly between groups. Subgroup analyses revealed that the pooled data were similar between the groups: 1st maximum (heel strike), -0.18 BW (P = 0.53); 1st minimum (mid-stance), -0.43 BW (P = 0.08); and 2nd maximum (toe off), -0.03 BW (P = 0.87). On gait analysis, there were no significant differences in vertical GRF, joint moment at stance, overall kinematics, walking speed, or cadence between UKA patients and TKA patients during level walking. However, the TKA group had significantly shorter stride length than UKA patients. Although the comparison was inconclusive in determining which types of knee arthroplasty offered the closest approximation to normal gait, we consider it important to provide better rehabilitation programs to reduce the abnormal stride length in TKA patients compared to UKA patients. 10.1371/journal.pone.0203310
    Increased Operative Time Impacts Rates of Short-Term Complications After Unicompartmental Knee Arthroplasty. Cregar William M,Goodloe J Brett,Lu Yining,Gerlinger Tad L The Journal of arthroplasty BACKGROUND:Previous evidence has demonstrated an exacerbating effect of increased operative time on short-term complications in total joint arthroplasty. While the same relationship may be expected for unicompartmental knee arthroplasty (UKA), supporting evidence remains sparse. The purpose of this study is to determine the impact of operative time on short-term complication rates after UKA and determine a critical threshold in operative times after which complications may increase. METHODS:The American College of Surgeons National Surgical Quality Improvement Project was queried from 2007 to 2018 to identify 11,633 UKA procedures that were included in the final analysis. The effect of operative time on complications within 30 days was evaluated using multivariate logistic regression models. Receiver operating characteristics curves and spline regression models were used to identify critical thresholds in operative time that increase the likelihood of short-term complications. RESULTS:Longer operative times (in minutes) were associated with higher rates of surgical site infection (90.4 ± 26.7 vs 84.8 ± 25.5, P = .003), blood transfusions (94.9 ± 28.6 vs 84.9 ± 25.5, P = .007), as well as reoperation rates (90.8 ± 27.9 vs 84.9 ± 25.5, P = .01), extended hospital length of stay (93.4 ± 29.8 vs 84.5 ± 25.2, P < .001), and mortality (110.4 ± 35.5 vs 84.9 ± 25.5, P = .008). Following multivariate logistic regression, operative time was found to independently predict increased surgical site infection, blood transfusion, myocardial infarction, extended length of stay, and mortality (odds ratio: 1.09 - 1.45, CI: 1.01 - 1.91, all P values <0.02). Receiver operating characteristics curves found an increase in mortality risk during the 30-day postoperative period after 88.5 minutes of operative time, a finding supported by spline regression plots. CONCLUSION:The present study found a positive correlation between increased operative times and short-term postoperative complication rates after UKA. Despite a statistically significant association with increasing operative time, odds ratios of reported complications are relatively low. 10.1016/j.arth.2020.08.032
    High Prevalence of Radiographic Outliers and Revisions with Unicompartmental Knee Arthroplasty. Kazarian Gregory S,Barrack Toby N,Okafor Louis,Barrack Robert L,Nunley Ryan M,Lawrie Charles M The Journal of bone and joint surgery. American volume BACKGROUND:Alignment outcomes and their impact on implant survival following unicompartmental knee arthroplasty (UKA) are unclear. The purpose of this study was to assess the implant survival and radiographic outcomes after UKA as well as the impact of component alignment and overhang on implant survival. METHODS:We performed a retrospective analysis of 253 primary fixed-bearing and mobile-bearing medial UKAs from a single academic center. All UKAs were performed by 2 high-volume fellowship-trained arthroplasty surgeons. UKAs comprised <10% of their knee arthroplasty practices, with an average of 14.2 medial UKAs per surgeon per year. Implant survival was assessed. Femoral coronal (FCA), femoral sagittal (FSA), tibial coronal (TCA), and tibial sagittal (TSA) angles as well as implant overhang were radiographically measured. Outliers were defined for FCA (>±10° deviation from neutral), FSA (>15° of flexion), TCA (>±5° deviation from neutral), and TSA (>±5° deviation from 7°). "Far outliers" were an additional >±2° of deviation. Outliers for overhang were identified as >3 mm for anterior overhang, >2 mm for posterior overhang, and >2 mm for medial overhang. RESULTS:Among patients with a failed UKA, revision was performed at an average of 3.7 years (range, 0.03 to 8.7 years). The cumulative revision rate was 14.2%. Kaplan-Meier survival analysis demonstrated 5 and 10-year survival rates of 88.0% (95% confidence interval [CI] = 82.0% to 91.0%) and 70.0% (95% CI = 56.0% to 80.0%), respectively. Only 19.0% (48) of the UKAs met target alignment for all 4 alignment measures, and only 72.7% (184) met all 3 targets for overhang. Only 11.9% (30) fell within all alignment and overhang targets. The risk of implant failure was significantly impacted by outliers for FCA (failure rate = 15.4%, p = 0.036), FSA (16.2%, p = 0.028), TCA (17.9%, p = 0.020), and TSA (15.2%, p = 0.034) compared with implants with no alignment or overhang errors (0%); this was also true for far outliers (p < 0.05). Other risk factors for failure were posterior overhang (failure rate = 25.0%, p = 0.006) and medial overhang (38.2%, p < 0.001); anterior overhang was not a significant risk factor (10.0%, p = 0.090). CONCLUSIONS:The proportions of UKA revisions and alignment outliers were greater than expected, even among high-volume arthroplasty surgeons performing an average of 14.2 UKAs per year (just below the high-volume UKA threshold of 15). Alignment and overhang outliers were significant risk factors for implant failure. LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence. 10.2106/JBJS.19.01277
    Unicompartmental Knee Arthroplasty Achieves Greater Flexion With No Difference in Functional Outcome, Quality of Life, and Satisfaction vs Total Knee Arthroplasty in Patients Younger Than 55 Years. A Propensity Score-Matched Cohort Analysis. Goh Graham Seow-Hng,Bin Abd Razak Hamid Rahmatullah,Tay Darren Keng-Jin,Chia Shi-Lu,Lo Ngai-Nung,Yeo Seng-Jin The Journal of arthroplasty BACKGROUND:Improvements in surgical techniques, implant design, and adherence to indications have resulted in favorable outcomes after unicompartmental knee arthroplasty (UKA), particularly in an older population. However, no studies have compared the performance of contemporary UKA and total knee arthroplasty (TKA) in a young population. METHODS:Prospectively collected registry data of 160 UKAs performed in 160 patients younger than 55 years were reviewed. Propensity scores generated using logistic regression were used to adjust for confounding variables of age, gender, body mass index, preoperative range of motion, Knee Society Score, Oxford Knee Score, and Short-Form 36, allowing matching of the TKA cohort to the UKA cohort in a 1:1 ratio using the nearest-neighbor method. RESULTS:The UKA group had significantly greater flexion at 6 months and 2 years (P < .001). There was no significant difference in Knee Society Score, Oxford Knee Score, and Short-Form 36. At 2 years, 89.4% and 88.8% of the TKA and UKA groups were satisfied (P = 1.00) while 86.9% and 86.3% had their expectations fulfilled (P = 1.00). At a mean follow-up of 7 years, there were 2 revisions in each group (2.2%). CONCLUSION:Although native knee biomechanics are preserved, younger patients do not seem to perceive this oft-cited benefit of UKA, as this did not translate into greater health-related quality of life or patient satisfaction compared to TKA. The theoretical advantages of UKA were not borne out by our findings, other than greater flexion up to 2 years postoperatively. 10.1016/j.arth.2017.09.022
    Robotic arm-assisted unicompartmental knee arthroplasty: high survivorship and good patient-related outcomes at a minimum five years of follow-up. Zambianchi Francesco,Daffara Valerio,Franceschi Giorgio,Banchelli Federico,Marcovigi Andrea,Catani Fabio Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Robotic arm-assisted unicompartmental knee arthroplasty (RA-UKA) has been shown to improve component placement, reduce intraoperative variability, increase patient satisfaction and improve short-term survivorship results. The aim of this retrospective study was to determine the incidence of revision and the clinical performance at a minimum of 5-year follow-up for a cohort of patients who received a medial RA-UKA. METHODS:Between April 2011 and July 2013, a total of 254 patients underwent medial RA-UKA at a single centre. Clinical performance was investigated using the Forgotten Joint Score-12 (FJS-12) and a 5-level Likert scale made of five items to assess joint perception and patient satisfaction. Kaplan-Meier implant survivorship was calculated and reasons for revision were collected. The effect of age, gender and body mass index (BMI) on the probability of reporting high FJS-12 and satisfaction were assessed. RESULTS:After considering exclusion criteria and loss to follow-up, a total of 216 patients (224 medial RA-UKAs) were assessed at a mean 5.9 years of follow-up. Five RA-UKAs underwent implant revision, resulting in an overall Kaplan-Meier survivorship of 97.8%. Unexplained knee pain (0.9%) was the most common reason for RA-UKA revision. Good-to-excellent FJS-12 scores and high satisfaction levels were reported at mid-term follow-up. Male patients had higher probability of having FJS-12 > 90 (p < 0.05) and high satisfaction levels (p < 0.05). CONCLUSIONS:RA-UKAs demonstrated high survivorship and good-to-excellent patient-reported outcome measures and satisfaction levels at minimum 5-year follow-up. Results for male patients had improved clinical performance when compared to female subjects. LEVEL OF EVIDENCE:IV. 10.1007/s00167-020-06198-9
    Kinematics of mobile-bearing unicompartmental knee arthroplasty compared to native: results from an in vitro study. Peersman Geert,Slane Josh,Vuylsteke Philippe,Fuchs-Winkelmann Susanne,Dworschak Philipp,Heyse Thomas,Scheys Lennart Archives of orthopaedic and trauma surgery INTRODUCTION:Fixed-bearing unicompartmental knee arthroplasty (UKA) closely replicates native knee kinematics. As few studies have assessed kinematics following mobile-bearing (MB) UKA, the current study aimed to investigate whether MB UKA preserves natural knee kinematics. MATERIALS AND METHODS:Seven fresh-frozen full-leg cadaver specimens were prepared and mounted in a kinematic rig that allowed all degrees of freedom at the knee. Three motion patterns, passive flexion-extension (0°-110° flexion), open-chain extension (5°-70° flexion) and squatting (30°-100° flexion), were performed pre- and post-implantation of a medial MB UKA and compared in terms of rotational and translational knee joint kinematics in the different anatomical planes, respectively. RESULTS:In terms of frontal plane rotational kinematics, MB UKA specimens were in a more valgus orientation for all motion patterns. In the axial plane, internal rotation of the tibia before and after UKA was consistent, regardless of motion task, with no significant differences. In terms of frontal plane, i.e., inferior-superior, translations, the FMCC was significantly higher in UKA knees in all flexion angles and motor tasks, except in early flexion during passive motion. In terms of axial plane, i.e., anteroposterior (AP), translations, during open-chain activities, the femoral medial condyle center (FMCC) tended to be more posterior following UKA relative to the native knee in mid-flexion and above. AP excursions of the FMCC were small in all tested motions, however. There was substantial AP translation of the femoral lateral condyle center during passive motion before and after UKA, which was significantly different for flexion angles > 38°. CONCLUSIONS:Our study data demonstrate that the kinematics of the unloaded knee following MB UKA closely resemble those of the native knee while relative medial overstuffing with UKA will result in the joint being more valgus. However, replacing the conforming and rigidly fixed medial meniscus with a mobile inlay may successfully prevent aberrant posterior translation of the medial femoral compartment during passive motion and squatting motion. 10.1007/s00402-017-2794-8
    Unicondylar Knee Arthroplasty Has Fewer Complications but Higher Revision Rates Than Total Knee Arthroplasty in a Study of Large United States Databases. Hansen Erik N,Ong Kevin L,Lau Edmund,Kurtz Steven M,Lonner Jess H The Journal of arthroplasty BACKGROUND:Unicondylar knee arthroplasty (UKA) has superior functional outcomes compared to total knee arthroplasty (TKA) with good mid-term and long-term survival data from high-volume institutions. We sought to quantify the risk of complications, re-operation/revision, hospital re-admission for any reason, and mortality of knee arthroplasty patients in the US patient population using 2 large databases. METHODS:UKA and TKA patients who were identified in the 2002-2011, 5% sample of Medicare data and 2004-2012 (June) MarketScan Commercial and Medicare Supplemental Databases were followed to evaluate the risk of complications, hospital re-admission for any reason, and mortality within 90 days of surgery. Survival probability defined by re-operation was calculated using the Kaplan-Meier method at 0.5, 2, 5, 7, and up to 10 years post-operatively. RESULTS:Compared to UKA, complication rates for TKA patients were significantly higher, including wound complication, pulmonary embolism, stiffness, peri-prosthetic joint infection, myocardial infarction, re-admission, and death. Age was found to be a significant risk factor (P < .05) for all complications in the Medicare cohort, except stiffness (P = .839), and all complications in the MarketScan cohort, except re-admission (P = .418), whereas gender had a variable effect on complications based on age. Survivorship of UKA was lower than TKA at all time points. Additionally, younger age adversely affected implant survival. By 7 years post-surgery, UKA survivorship in the Medicare and MarketScan cohorts was 80.9% and 74.4%, respectively. In contrast, TKA survivorship for the same cohorts was 95.7% and 91.9% by the same time point. CONCLUSION:Patients undergoing UKA have fewer post-operative complications and re-admissions than those undergoing TKA. However, patients undergoing UKA have a higher rate of re-operation and revision at up to 10 years of follow-up. It appears that age, as well as surgeon and hospital volume significantly impacts implant survivorship while gender does not have a relation. LEVEL OF EVIDENCE:Level III. 10.1016/j.arth.2019.04.004
    Unicompartmental knee arthroplasty fails to completely restore normal gait patterns during level walking. Kim Myung-Ku,Yoon Jung-Ro,Yang Se-Hyun,Shin Young-Soo Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Gait analysis is a valuable instrument for measuring function objectively after unicompartmental knee arthroplasty (UKA). However, most gait analysis studies have reported conflicting results for functional assessment after UKA. This meta-analysis compared the gait patterns of UKA patients and healthy controls during level walking. METHODS:Studies were included in the meta-analysis if they recorded vertical ground reaction force (GRF), flexion at initial contact, flexion at loading response, extension at mid-stance, flexion at swing, walking speed, cadence, and stride length in UKA patients or healthy controls. RESULTS:Seven studies met the criteria for inclusion in the meta-analysis. The UKA patients and healthy controls were similar in terms of vertical GRF (95% CI - 0.54 to 0.23; ns), flexion at initial contact (95% CI - 0.47 to 4.96; ns), flexion at loading response (95% CI - 1.29 to 3.69; ns), and flexion at swing (95% CI - 8.85 to 0.40; ns). In contrast, extension at mid-stance (95% CI 0.53 to 4.88; P = 0.01), walking speed (95% CI - 2.13 to - 0.15; P = 0.02), cadence (95% CI - 1.02 to - 0.25; P = 0.001), and stride length (95% CI - 2.02 to - 0.22; P = 0.01) differed significantly between groups. Subgroup analyses revealed that the pooled data were similar between groups: 1st maximum (heel strike), - 0.43 BW (ns); 1st minimum (mid-stance), 0.61 BW (ns); and 2nd maximum (toe off), - 0.46 BW (ns). CONCLUSIONS:There were no significant differences in vertical GRF or overall kinematics in the sagittal plane between UKA patients and healthy controls during level walking. However, the UKA group had a significantly slower walking speed and cadence and a shorter stride length than healthy controls. The current findings suggest that, clinically, UKA fails to completely restore normal gait patterns. LEVEL OF EVIDENCE:Level II, therapeutic study. 10.1007/s00167-018-4863-0
    Unicompartmental knee arthroplasty: Current indications, technical issues and results. Rodríguez-Merchán E Carlos,Gómez-Cardero Primitivo EFORT open reviews An age younger than 60 years, a body weight of 180 lb (82 kg) or more, performing heavy work, having chondrocalcinosis and having exposed bone in the patellofemoral (PF) joint are not contraindications for unicompartmental knee arthroplasty (UKA).Severe wear of the lateral facet of the PF joint with bone loss and grooving is a contraindication for UKA.Medial UKA should only be performed in cases of severe osteoarthritis (OA) as shown in pre-operative X-rays, with medial bone-on-bone contact and a medial/lateral ratio of < 20%.The post-operative results of UKA are generally good. Medium-term and long-term studies have reported acceptable results at 10 years, with implant survival greater than 95% for UKAs performed for medial OA or osteonecrosis and for lateral UKA, especially when fixed-bearing implants are used.When all implant-related re-operations are considered, the 10-year survival rate is 94%, and the 15-year survival rate is 91%.Aseptic loosening is the principal failure mechanism in the first few years in mobile-bearing implants, whereas OA progression causes most failures in later years in fixed-bearing implants.The overall complication rate and the comprehensive re-operation rate are comparable in both mobile bearings and fixed bearings.The survival likelihood of the all-polyethylene UKA implant is similar to that of metal-backed modular designs for UKA.Notable cost savings of approximately 50% can be achieved with an outpatient UKA surgery protocol. Outpatient surgery for UKA is efficacious and safe, with satisfactory clinical results thus far. Cite this article: 2018;3:363-373. DOI: 10.1302/2058-5241.3.170048. 10.1302/2058-5241.3.170048
    An Experienced Surgeon Can Meet or Exceed Robotic Accuracy in Manual Unicompartmental Knee Arthroplasty. Bush Ashleigh N,Ziemba-Davis Mary,Deckard Evan R,Meneghini R Michael The Journal of bone and joint surgery. American volume BACKGROUND:Reports in the literature indicate that implant placement is more accurate with robotic-assisted unicompartmental knee arthroplasty (UKA); however, these studies have not always accounted for surgeon experience. The purpose of the present study was to compare the accuracy of tibial component alignment in UKA between an experienced high-volume surgeon and the published data on robotic-assisted surgery. METHODS:The radiographs made before and after 128 consecutive medial UKAs performed manually by a single surgeon using a cemented fixed-bearing implant were reviewed. Native tibial and tibial implant slope and varus alignment of the tibial implant were measured on preoperative and postoperative lateral and anteroposterior radiographs, respectively. The percentages of knees in which the postoperative measurements were within preoperative targets and the root mean square (RMS) error rates between the planned and achieved targets were compared with published robotic-assisted-UKA data. RESULTS:In the present study, the proportion of manual UKAs in which the tibial component alignment was within the preoperative target was 66% (85 of 128), which exceeded published values in a study comparing robotic (58%) with manual (41%) UKA. The RMS error for tibial component alignment in the present study (1.48°) was less than published RMS error rates for robotic UKAs (range, 1.8° to 5°). Fifty-eight percent (74) of the 128 study UKAs were within the surgeon's preoperative goal for tibial slope, which was closer to the published value of 80% for robotic UKAs than is the published rate of 22% for manual UKAs. The RMS error for tibial slope in the study UKAs (1.50°) was smaller than the published RMS error rates for tibial slope in robotic UKAs (range, 1.6° to 1.9°). CONCLUSIONS:Accurate implant alignment is important in UKA. In this study, an experienced surgeon achieved or exceeded robotic accuracy of tibial implant alignment in UKA. However, the relationship between implant position and patient outcomes is unknown, and a consensus on ideal surgical targets for optimal implant survivorship has yet to be established. LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence. 10.2106/JBJS.18.00906
    Revision of Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty: Is It as Good as a Primary Result? Lombardi Adolph V,Kolich Mark T,Berend Keith R,Morris Michael J,Crawford David A,Adams Joanne B The Journal of arthroplasty BACKGROUND:Unicompartmental knee arthroplasty (UKA) is touted as a more conservative, bone- and tissue-sparing procedure than total knee arthroplasty (TKA). Similarly, revision of UKA to TKA is generally a simpler procedure than revision of TKA to TKA and can be accomplished with primary TKA components in most cases. The purpose of this study was to review a consecutive series of patients undergoing revision of failed UKA to TKA to determine if etiology is similar to that reported in recent literature and evaluate if the results align more with primary TKA vs revision of TKA to TKA. METHODS:A query of our private practice registry from 1996 to 2015 revealed 184 patients (193 knees) who underwent revisions of failed UKA with minimum 2-year follow-up. The mean age was 63.5 (37-84) years, body mass index was 32.3 (19-57) kg/m, and interval after UKA was 4.8 (0-35) years. The most prevalent indications for UKA revision were aseptic loosening (42%) arthritic progression (20%), and tibial collapse (14%). RESULTS:At 6.1-year mean follow-up (2-20), 8 knees (4.1%) required re-revision, which is similar to what we reported at 5.5 years in a group of primary TKA patients (6 of 189; 3.2%) and much lower than what we observed at 6.0 years in a recent study of aseptic revision TKA patients (35 of 278; 12.6%). In the study group, Knee Society clinical and function scores improved from 50.8 and 52.1 preoperatively to 83.4 and 67.6 at the most recent evaluation. Re-revisions were for aseptic loosening (3), instability (2), arthrofibrosis (2), and infection (1). CONCLUSIONS:Compared to published individual institution and national registry data, re-revision rates of failed UKA are equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA. 10.1016/j.arth.2018.03.023
    Medium-term outcome of cementless, mobile-bearing, unicompartmental knee arthroplasty. Stempin Radosław,Stempin Kacper,Kaczmarek Wiesław Annals of translational medicine Background:Cemented, mobile-bearing unicondylar knee arthroplasty (UKA) yields good functional results. However, radiolucent lines (RLL) are not uncommon, even in asymptomatic patients, and it has been debated whether these "physiological" RLLs are indicative of loosening. Cementless UKA may lead to fewer RLLs compared with cemented devices. The present study was designed to document mid-term outcome with an emphasis on clinical outcomes. Methods:We included 153 knees of 150 consecutive patients in a retrospective study. All patients had received a cementless medial mobile-bearing UKA. Patients were evaluated with use of the Knee Society Score (KSS), which was obtained at baseline and at final follow-up. The WOMAC, Oxford Knee Score (OKS) and Forgotten Joint Scores (FJS-12) were administered at the final follow-up. Anteroposterior (AP) and lateral radiographs were taken at final follow-up. Results:At a mean follow-up of 5 years (range, 3-7 years), implant survival was 97.1% (95% confidence interval, 91.1-99.1%). Excellent postoperative KSS, WOMAC, OKS and FJS scores were obtained. Postoperative radiography was available for 78 knees. RLL was observed in 10.3% of the cases, but no cases with complete RLLs were seen. Conclusions:Favourable results were found for cementless, mobile-bearing UKA, with no aseptic loosening at an average follow-up of 5 years. Cementless UKA fixation may lead to a clinically "forgotten joint" and may decrease the rate of RLLs. 10.21037/atm.2018.12.50
    The unicompartmental knee is the preferred side in individuals with both a unicompartmental and total knee arthroplasty. Wiik Anatole Vilhelm,Nathwani Dinesh,Akhtar Ahsan,Al-Obaidi Bilal,Strachan Robin,Cobb Justin Peter Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:To determine the preferred knee in patients with both one total and one unicompartmental knee arthroplasty. METHOD:Patients simply with a unicompartmental (UKA) and total knee arthroplasty (TKA) on contralateral sides were retrospectively screened from three senior knee surgeon's logs over a 15 year period. Patients safe and free from other diseases to affect gait were approached. A total of 16 patients (mean age 70 ± 8) agreed to ground reaction force testing on an instrumented treadmill at a fair pace and incline. A gender-ratio identical group of 16 healthy control subjects (mean age 67 ± 10) and 16 patients with ipsilateral medial knee OA (mean age 66 ± 7) were analysed to compare. RESULTS:Radiographically the mode preoperative Kellgren-Lawrence knee grade for each side was 3. Postoperatively, the TKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 89° with a mean posterior slope of 5° in the sagittal plane. The UKA side had a mean coronal femoral component alignment of 7° and a mean tibial coronal alignment of 86° with a mean posterior slope of 4° in the sagittal plane. In 7 patients, the TKA was the first procedure, while 6 for the UKA and 3 done simultaneously. Gait analysis demonstrated in both walking conditions the UKA limb was the preferred side through all phases of loading (p < 0.05) and nearer to normal than the TKA limb when compared to healthy controls and patients with knee OA. The greatest difference was observed between the transition of weight acceptance and midstance (p = 0.008), when 22% more load was taken by the UKA side. CONCLUSION:By using a dynamic metric of an everyday activity, a distinct gait difference between differing arthroplasty types were established. A more natural loading pattern can be achieved with unicompartmentals as compared to total knees. LEVEL OF EVIDENCE:Retrospective comparative study, Level III. 10.1007/s00167-019-05814-7
    A novel preoperative scoring system for the indication of unicompartmental knee arthroplasty, as predictor of clinical outcome and satisfaction. Antoniadis Alexander,Dimitriou Dimitris,Canciani Jean Pierre,Helmy Naeder Archives of orthopaedic and trauma surgery INTRODUCTION:Proper patient selection is a crucial factor for the outcome of the unicompartmental knee arthroplasty (UKA). However, there is still not a clear consensus on which patients could benefit the utmost from a UKA. The purpose of this prospective study was to introduce a novel, preoperative, predictive score (Unicompartmental Indication Score, UIS) to aid proper patient selection in UKA. MATERIALS AND METHODS:A total of 152 patients with an average age of 68 years and a mean follow-up of 27 months were evaluated preoperatively with the UIS and postoperative at every follow-up. Correlation analysis was applied to identify potential relationships between the UIS, functional outcomes, pain relief, patient satisfaction, and range of motion. The ROC analysis was used to identify the best cutoff value of the UIS, which would have predicted an optimal outcome following UKA. RESULTS:The majority of the patients (91%) were satisfied with the operation, with 61% reporting excellent and 30% good satisfaction. The UIS was positively correlated to the postoperative Knee Society Score (KSS) for both pain (r = 0.26, p < 0.001) and function (r = 0.31, p < 0.001). The UIS was also positively correlated to the patient satisfaction (p = 0.46, p < 0.001) and maximum postoperative flexion (r = 0.25, p < 0.001). The ROC analysis provided an ideal cutoff for UIS at 25 points (sensitivity: 75%, sensibility: 93%, area under the curve: 86%). At a mean follow-up of 27 months (range 24-37), we observed three revisions in 152 consecutive UKA with a mean UIS of 27 points (range 20-30). CONCLUSIONS:The newly introduced UIS score might be a reliable preoperative scoring system to predict patients with excellent satisfaction, functional outcome, pain relief and possibly implant survivorship following UKA, and therefore, could help the proper patient selection and decision-making in UKA. LEVEL-OF-EVIDENCE:Prospective study, II. 10.1007/s00402-018-3069-8
    Greater activity, better range of motion and higher quality of life following unicompartmental knee arthroplasty: a comparative case-control study. Hauer Georg,Sadoghi Patrick,Bernhardt Gerwin A,Wolf Matthias,Ruckenstuhl Paul,Fink Andrea,Leithner Andreas,Gruber Gerald Archives of orthopaedic and trauma surgery PURPOSE:The purpose of this study was to provide a matched cohort comparison of clinical and functional outcome scores, range of motion and quality of life following unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA). The hypothesis was that patients receiving UKA report better results than comparable patients who receive conventional TKA. METHODS:Clinical and functional results of 35 patients with medial end-stage osteoarthritis who had received a fixed-bearing UKA were compared with the results of 35 matched patients who had received a TKA from the same manufacturer by the same surgeon. Outcome scores were measured before surgery and at final follow-up using Tegner Activity Scale (TAS), range of motion (ROM) and Short Form 36 Health Survey (SF-36). The Knee Society Score (KSS) was assessed at final follow-up. The mean observation period was 2.3 years in both groups. RESULTS:The preoperative knee scores had no statistically significant differences between the two groups. Postoperatively, however, UKAs performed significantly better regarding TAS and ROM (4 vs. 3 and 118.4 vs. 103.7, respectively). The results of the SF-36 showed significantly better results for the UKA group in the mental component summary score and in the subscale of social function. CONCLUSIONS:The present study suggests that UKA is associated with higher activity level, higher quality of life, and greater ROM when compared with TKA on comparable patients. Prolonged clinical follow-up in a larger patient cohort with a randomised-controlled study design would be beneficial to confirm these findings. LEVEL OF EVIDENCE:III. 10.1007/s00402-019-03296-3
    Larger range of motion and increased return to activity, but higher revision rates following unicompartmental versus total knee arthroplasty in patients under 65: a systematic review. Kleeblad Laura J,van der List Jelle P,Zuiderbaan Hendrik A,Pearle Andrew D Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Due to the lack of comparative studies, a systematic review was conducted to determine revision rates of unicompartmental and total knee arthroplasty (UKA and TKA), and compare functional outcomes, range of motion and activity scores in patients less than 65 years of age. METHODS:A literature search was performed using PubMed, Embase, and Cochrane systems since 2000. 27 UKA and 33 TKA studies were identified and included. Annual revision rate (ARR), functional outcomes, and return to activity were assessed for both types of arthroplasty using independent t tests. RESULTS:Four level I studies, 12 level II, 16 level III, and 29 level IV were included, which reported on outcomes in 2224 UKAs and 4737 TKAs. UKA studies reported 183 revisions, yielding an ARR of 1.00 and extrapolated 10-year survivorship of 90.0%. TKA studies reported 324 TKA revisions, resulting in an ARR of 0.53 and extrapolated 10-year survivorship of 94.7%. Functional outcomes scores following UKA and TKA were equivalent, however, following UKA larger ROM (125° versus 114°, p = 0.004) and higher UCLA scores were observed compared to TKA (6.9 versus 6.0, n.s.). CONCLUSION:These results show that good-to-excellent outcomes can be achieved following UKA and TKA in patients less than 65 years of age. A higher ARR was noted following UKA compared to TKA. However, improved functional outcomes, ROM and return to activity were found after UKA than TKA in this young population. Comparative studies are needed to confirm these findings and assess factors contributing to failure at the younger patient population. Outcomes of UKA and TKA in patients younger than 65 years are both satisfying, and therefore, both procedures are not contraindicated at younger age. UKA has several important advantages over TKA in this young and frequently more active population. LEVEL OF EVIDENCE:IV. 10.1007/s00167-017-4817-y
    Should Medicare Remove Total Knee Arthroplasty From Its Inpatient Only List? A Total Knee Arthroplasty Is Not a Partial Knee Arthroplasty. Courtney P Maxwell,Froimson Mark I,Meneghini R Michael,Lee Gwo-Chin,Della Valle Craig J The Journal of arthroplasty BACKGROUND:The Centers for Medicare and Medicaid Services have solicited comments to consider removing total knee arthroplasty (TKA) from the Inpatient Only list, as it has done for unicompartmental knee arthroplasty (UKA). The purpose of this study is to determine whether Medicare-aged patients undergoing TKA had comparable outcomes to those undergoing UKA. METHODS:We queried the American College of Surgeons-National Surgical Quality Improvement Program database for all patients aged 65 years or older who underwent elective TKA or UKA from 2014 and 2015. Demographic variables, comorbidities, length of stay (LOS), 30-day complication, and readmission rates were compared between UKA and TKA patients. A multivariate regression analysis was then performed to identify independent risk factors for complications and hospital LOS greater than 1 day. RESULTS:Of the 50,487 patients in the study, there were 49,136 (97%) TKA patients and 1351 UKA patients (3%). Medicare-aged TKA patients had a longer mean LOS (2.97 vs 1.57 days, P < .001), had a higher complication rate (9% vs 3%, P < .001), and were more likely to be discharged to a rehabilitation facility (31% vs 9%, P < .001) than Medicare-aged UKA patients. When controlling for other variables, TKA patients were more likely to experience a complication (odds ratio, 2.562; P < .001) and require LOS >1 day (odds ratio, 14.679; P < .001) than UKA patients. CONCLUSION:TKA procedure in the Medicare population is an independent risk factor for increased complications and LOS compared to UKA. Policymakers should use caution extrapolating UKA data to TKA patients and recognize the inherent disparities between the 2 procedures. 10.1016/j.arth.2017.11.028
    Mobile-bearing unicompartmental knee arthroplasty in old-aged patients demonstrates superior short-term clinical outcomes to open-wedge high tibial osteotomy in middle-aged patients with advanced isolated medial osteoarthritis. Cho Won-Joon,Kim Jong-Min,Kim Won-Kyeong,Kim Dong-Eun,Kim Nam-Ki,Bin Seong-Il International orthopaedics PURPOSE:The aim of the present study was to compare the clinical outcomes of mobile-bearing unicompartmental knee arthroplasty (MB-UKA) and open-wedge high tibial osteotomy (OWHTO) for advanced isolated medial osteoarthritis (OA). METHODS:Patients with advanced medial compartment OA (Ahlbäck grade ≥ II) who underwent either MB-UKA with Oxford Knee or OWHTO were included. The minimum follow-up was two years. Clinical outcomes were evaluated using the Hospital for Special Surgery (HSS) score, knee score (KS), and function score (FS) of the Knee Society Knee Scoring System. Pre-operative and post-operative values were compared within groups. Pre-operative and post-operative values and the degree of change were compared between the two groups. Radiologic progression of OA in either the lateral or patellofemoral compartment was evaluated. RESULTS:Forty knees (20 received MB-UKA, 20 received OWHTO) were enrolled. The mean age was higher in the MB-UKA group (67.9 ± 9.0 years) than in the OWHTO group (58.4 ± 5.5 years). The HSS score, KS, and FS were significantly increased post-operatively in both groups. The preoperative HSS score, KS, and FS were significantly lower in the MB-UKA than in the OWHTO group; however, only the post-operative HSS score was significantly higher in the MB-UKA group. The changes in HSS score and KS were also greater in the MB-UKA group. There was no significant difference in OA progression. CONCLUSIONS:Although there was an age difference between the two groups, MB-UKA demonstrated superior short-term clinical outcomes to OWHTO for advanced isolated medial OA. In particular, MB-UKA was more effective in terms of pain relief. 10.1007/s00264-018-3880-4
    Does Patellofemoral Disease Affect Outcomes in Contemporary Medial Fixed-Bearing Unicompartmental Knee Arthroplasty? Deckard Evan R,Jansen Kirsten,Ziemba-Davis Mary,Sonn Kevin A,Meneghini R Michael The Journal of arthroplasty BACKGROUND:Pre-existing patellofemoral disease has traditionally been a contraindication to unicompartmental knee arthroplasty (UKA), as proposed by Kozinn and Scott. More recently, some propose that patellofemoral disease can be ignored in UKA; however, the supporting research is predominantly in mobile-bearing designs. The study purpose was to evaluate the effect of patellofemoral disease osteoarthritis severity on latest outcomes after fixed-bearing medial UKA. METHODS:A retrospective review of 147 consecutive medial fixed-bearing UKAs with minimum 1-year follow-up was performed. The medial and lateral patellofemoral compartments were graded according to the Kellgren & Lawrence grading system, Osteoarthritis Research Society International atlas, and intraoperative assessment performed using the Outerbridge classification. Prospectively collected University of California Los Angeles Activity Level, modern Knee Society pain and function scores, and Likert scale satisfaction were correlated with presence and severity of pre-existing patellofemoral disease. RESULTS:One hundred forty-three medial UKAs were analyzed with mean age, body mass index, and follow-up of 64.1 years, 30.7 kg/m, and 24.0 months, respectively. No correlations were observed between patellofemoral disease severity and patient-reported outcome measures at latest follow-up or improvement scores for Kellgren & Lawrence grading system or Osteoarthritis Research Society International atlas (P ≥ .058). Improvement in activity level scores was significantly higher for patients with less patellar and trochlear chondral damage despite not reaching minimal clinically important difference of 2.0 (P ≤ .028). Regardless of patellofemoral disease severity, 93% of UKAs were satisfied or very satisfied. CONCLUSION:Clinical outcomes of fixed-bearing medial UKA were not adversely impacted by intraoperatively visualized or radiographically evaluated patellofemoral disease. Furthermore, long-term follow-up is warranted and caution should be used before considering patellofemoral disease as a contraindication for UKA. 10.1016/j.arth.2020.03.007
    The outcomes of mobile bearing unicompartmental knee arthroplasty and total knee arthroplasty on anteromedial osteoarthritis of the knee in the same patient. Pongcharoen Boonchana,Timjang Jitisak Archives of orthopaedic and trauma surgery INTRODUCTION:Compared to total knee arthroplasty (TKA), mobile-bearing unicompartmental knee arthroplasty (UKA) is associated with better outcomes, such as an earlier recovery, less postoperative pain, lower morbidity and mortality, and a greater "feel" of a normal knee. However, no study has reported the clinical outcomes in patients with the same stage of osteoarthritis of the knee. The purpose of this study was to determine the clinical outcomes, including the Joint Forgotten Score (JFS), Oxford Knee Score (OKS), Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Kujala score after UKA on one knee and TKA on the opposite knee in the same patient. MATERIALS AND METHODS:We retrospectively reviewed 32 patients with anteromedial OA who underwent mobile-bearing UKA in one knee and TKA in the other knee from 2009 to 2017. The JFS, OKS, KSS, KOOS, and Kujala scores were recorded and compared between the groups. Patients' preferences between UKA and TKA and satisfaction were also recorded. RESULTS:The JFS and KOOS in the UKA group were significantly (p = 0.01, 0.01) higher than those in the TKA group: 97.01 ± 3.26 (89.58-100) vs. 94.92 ± 3.34 (87.80-100) and 91.16 ± 2.67 (85.25-96) vs. 89.24 ± 2.67 (84.50-94.71), respectively. The OKS, KSS, and Kujala scores were not different between the two groups (p = 0.82, 0.95, and 0.31, respectively) and neither was patient preference (p = 0.41) or satisfaction (p = 0.42). The mean follow-up was 48.36 months (range 24.00-96.00 months), during which there were no postoperative complications. CONCLUSION:UKA was associated with a better JFS and KOOS but was otherwise comparable to TKA and may be preferable. 10.1007/s00402-020-03527-y
    Should patients aged 75 years or older undergo medial unicompartmental knee arthroplasty? A propensity score-matched study. Liow Ming Han Lincoln,Goh Graham S,Pang Hee-Nee,Tay Darren Keng-Jin,Chia Shi-Lu,Lo Ngai-Nung,Yeo Seng-Jin Archives of orthopaedic and trauma surgery INTRODUCTION:With increasing life expectancies worldwide, more elderly patients with isolated medial compartment osteoarthritis may become suitable UKA candidates. However, there is a paucity of literature comparing outcomes between older patients (≥ 75 years) and younger patients undergoing UKA. The aim of this study was to determine if there were differences in functional and HRQoL measures between older patients (≥ 75 years) and younger controls (< 75 years) undergoing primary UKA. MATERIALS AND METHODS:Prospectively collected registry data of 1041 patients who underwent primary, cemented, fixed-bearing medial UKA at a single institution from 2002-2013 were reviewed. Propensity scores generated using logistic regression was used to match older patients (≥ 75 years, n = 94) to controls (< 75 years, n = 188) in a 1:2 ratio. Knee Society Scores, Oxford Knee Score, Short Form-36, satisfaction/expectation scores, proportion of patients attaining OKS/SF-36 PCS MCID and survivorship were analysed. RESULTS:Patients ≥ 75 years had significantly lower KSFS (67.1 ± 17.9 vs 79.4 ± 18.2, p < 0.001) and SF-36 PCS (47.3 ± 10.1 vs 50.4 ± 9.1, p = 0.01) as compared to the control group. In addition, a significantly lower proportion of patients ≥ 75 years attained MCID for SF-36 PCS when compared to the controls (50.0% vs 63.8%, p = 0.04). Survival rates at mean 8.3 ± 3.0 years were 98.9% (95% CI, 96.7-100) in the older group versus 92.8% (95% CI, 86.8-98.8) in the younger group (p = 0.31). CONCLUSIONS:Our findings highlight the need to counsel older patients regarding potentially reduced improvements in functional outcomes, despite advantages of lower revision. However, UKA in older patients continues to be a viable option for isolated medial compartment osteoarthritis LEVEL OF EVIDENCE: Level III Propensity score matched study. 10.1007/s00402-020-03440-4
    General Anesthesia Leads to Increased Adverse Events Compared With Spinal Anesthesia in Patients Undergoing Unicompartmental Knee Arthroplasty. Lu Yining,Cregar William M,Goodloe J Brett,Khazi Zain,Forsythe Brian,Gerlinger Tad L The Journal of arthroplasty BACKGROUND:The volume of unicompartmental knee arthroplasty (UKA) has increased dramatically in recent years with good reported long-term outcomes. UKA can be performed under general or neuraxial (ie, spinal) anesthesia; however, little is known as to whether there is a difference in outcomes based on anesthesia type. The purpose of the present study is to compare perioperative outcomes between anesthesia types for patients undergoing primary elective UKA. METHODS:Patients who underwent primary elective UKA from 2007 to 2017 were identified from the American College of Surgeons-National Surgical Quality Improvement Program Database. Operating room times, length of stay (LOS), 30-day adverse events, and readmission rates were compared between patients who received general anesthesia and those who received spinal anesthesia. Propensity-adjusted multivariate analysis was used to control for selection bias and baseline patient characteristics. RESULTS:A total of 8639 patients underwent UKA and met the inclusion criteria for this study. Of these, 4728 patients (54.7%) received general anesthesia and 3911 patients (45.3%) received spinal anesthesia. On propensity-adjusted multivariate analyses, general anesthesia was associated with increased operative time (P < .001) and the occurrence of any severe adverse event (odds ratio [OR], 1.39; 95% confidence interval [95% CI], 1.04-1.84; P = .024). In addition, general anesthesia was associated with higher rates of deep venous thrombosis (OR, 2.26; 95% CI, 1.11-4.6; P = .024) and superficial surgical site infection (OR, 1.04; 95% CI, 0.6-1.81; P < .001). Finally, general anesthesia was also associated with a reduced likelihood of discharge to home (OR, 0.72; 95% CI, 0.59-0.88; P < .001). No difference existed in postoperative hospital LOS or readmission rates among cohorts. CONCLUSION:General anesthesia was associated with an increased rate of adverse events and increased operating room times as well as a reduced likelihood of discharge to home. There was no difference in hospital LOS or postoperative readmission rates between anesthesia types. 10.1016/j.arth.2020.03.012
    Trends and risk factors for prolonged opioid use after unicompartmental knee arthroplasty. Bedard N A,DeMik D E,Dowdle S B,Callaghan J J The bone & joint journal AIMS:The purpose of this study was to evaluate trends in opioid use after unicompartmental knee arthroplasty (UKA), to identify predictors of prolonged use and to compare the rates of opioid use after UKA, total knee arthroplasty (TKA) and total hip arthroplasty (THA). MATERIALS AND METHODS:We identified 4205 patients who had undergone UKA between 2007 and 2015 from the Humana Inc. administrative claims database. Post-operative opioid use for one year post-operatively was assessed using the rates of monthly repeat prescription. These were then compared between patients with and without a specific variable of interest and with those of patients who had undergone TKA and THA. RESULTS:A total of 4205 UKA patients were analysed. Of these, 1362 patients (32.4%) were users of opioids. Pre-operative opioid use was the strongest predictor of prolonged opioid use after UKA. Opioid users were 1.4 (81.6% 57.7%), 3.7 (49.5% 13.3%) and 5.5 (35.8% 6.5%) times more likely to be taking opioids at one, two and three months post-operatively, respectively (p < 0.05 for all). Younger age and specific comorbidities such as anxiety/depression, smoking, back pain and substance abuse were found to significantly increase the rate of repeat prescription for opioids after UKA. Overall, UKA patients required significantly less opioid prescriptions than patients who had undergone THA and TKA. CONCLUSION:One-third of patients who undergo UKA are given opioids in the three months pre-operatively. Pre-operative opioid use is the best predictor of increased repeat prescriptions after UKA. However, other intrinsic patient characteristics are also predictive. Cite this article: 2018;100-B(1 Supple A):62-7. 10.1302/0301-620X.100B1.BJJ-2017-0547.R1
    Unicondylar vs. total knee arthroplasty in medial osteoarthritis: a retrospective analysis of registry data and functional outcome. Liebensteiner Michael,Köglberger Paul,Ruzicka Alexander,Giesinger Johannes M,Oberaigner Wilhelm,Krismer Martin Archives of orthopaedic and trauma surgery PURPOSE:It was the aim of our study to compare the functional outcome (WOMAC score, range of motion) achieved with unicondylar knee arthroplasty (UKA) and total knee arthroplasty (TKA). It was hypothesized that UKA and TKA would differ with regard to the WOMAC function scale (hypothesis 1) and the WOMAC total scale (hypothesis 2). It was assumed that the groups would differ with respect to changes in range of motion (ROM) over time (hypothesis 3). METHODS:A retrospective comparative study was conducted to analyze data available from the federal state's Arthroplasty Registry (WOMAC score) and from clinical routine (ROM). Patients who underwent UKA or TKA between 2008 and 2015 were considered. ANOVAs for repeated measurements were applied, adjusted for age, to test hypotheses 1-3. RESULTS:The UKA group was comprised of 112 patients (age 65, BMI 29). The TKA group included 330 cases (age 69, BMI 29). Regarding hypothesis 1, the amount of improvement in WOMAC function was not influenced by the surgical group (no significant group*time interactions, p = 0.608). Similarly, for hypothesis 2, the amount of improvement in the WOMAC total score was not influenced by the surgical group (no significant group*time interactions, p = 0.392). Regarding hypothesis 3, we found no significant group*time interaction for the ROM data (p = 0.731). CONCLUSIONS:On the basis of our findings, it is concluded that whether knee osteoarthritis is treated with either medial UKA or TKA has no influence on the WOMAC total score or any of the WOMAC subscales. It has no effect on early or late ROM gain. 10.1007/s00402-020-03377-8
    Is Mobile-Bearing Medial Unicompartmental Knee Arthroplasty Appropriate for Asian Patients With the Risk of Bearing Dislocation? Kang Suk-Woong,Kim Kyung-Taek,Hwang Youn-Soo,Park Won-Ro,Shin Jong-Ki,Song Moo-Ho The Journal of arthroplasty BACKGROUND:Mobile-bearing unicompartmental knee arthroplasty (UKA) is an attractive operation for medial unicompartmental knee arthritis, but unexpected bearing dislocation is a drawback. Bearing dislocation occurs more frequently in Asians, whose lifestyle involves deeper knee flexion than Westerners. This study investigated whether mobile-bearing medial UKA is appropriate for Asians by analyzing (1) the rate of bearing dislocation and (2) the results of patients with bearing dislocation. METHODS:We retrospectively reviewed 531 consecutive mobile-bearing medial UKA in the previous 15 years, including 22 patients with bearing dislocation who had at least 2 years of follow-up. The entire patient cohort was divided into 2 groups: the symmetrical bearing (187 knees) and the anatomic bearing (344 knees) groups. In the anatomic bearing group, patients who underwent surgery using the conventional phase III (283 knees) vs the Microplasty (61 knees) instrumentation systems were compared. RESULTS:The overall incidence of bearing dislocation was 4.1% (22/531). Patients with the symmetrical bearing displayed a relatively high dislocation rate of 9.6% (18/187), which significantly decreased to 1.1% (4/344) after changing to the anatomic bearing (P < .001). In the anatomic bearing group, the dislocation rate with the conventional phase III system was 1.4% (4/283). There were no bearing dislocations in the Microplasty system group (0%, 0/61) after at least 2 years of follow-up. CONCLUSION:Although mobile-bearing medial UKA was reported to have a high incidence of bearing dislocation in Asians, this frequency of dislocation is drastically decreased by bearing design and implantation system improvements. We consider mobile-bearing medial UKA appropriate for Asians. 10.1016/j.arth.2019.12.036
    No difference in patient satisfaction after mobile bearing or fixed bearing medial unicompartmental knee arthroplasty. Pronk Yvette,Paters Angela Anna Maria,Brinkman Justus-Martijn Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Medial unicompartmental knee arthroplasty (UKA) has excellent survival rates using one of the two implant designs: mobile bearing (MB) or fixed bearing (FB). There is a lack of studies comparing patient-reported outcomes (PROs) of both implants. This study aimed to document and compare PROs of MB UKA to FB UKA at 6, 12 and 24 months after surgery. METHODS:A single high-volume surgeon, retrospective cohort study with prospectively collected data of two groups of UKA patients, with a MB (n = 66) or FB (n = 97) implant. Primary outcome was patient satisfaction (0-10; NRS). Secondary outcomes were pain at rest (NRS), pain during activity (NRS), function (OKS, KOOS-PS), quality of life (EQ-5D-3L), anchor pain, anchor function and anchor recovery. PROs were collected 6, 12 and 24 months postoperatively. The complication rate and revision rate within one year after surgery were recorded. RESULTS:For the MB group, the median NRS satisfaction score was 9.0 (8.0-10.0) compared to 9.0 (8.0-9.5) for the FB group at 6 months (p = 0.620). Similar scores were found at 12 and 24 months; both MB 9.0 (8.0-10.0) and FB 9.0 (8.0-10.0) (p = 0.556 and p = 0.522, respectively). There were no statistically significant differences between MB and FB groups in all secondary outcomes postoperatively. CONCLUSION:Medial UKA performed by a high-volume surgeon, using a MB or a FB implant, results in excellent patient satisfaction, pain relief, functional improvement and quality of life improvement at 6, 12 and 24 months after surgery. The recommendation and use of one over the other is not justified based on the outcomes in the current study. LEVEL OF EVIDENCE:III. 10.1007/s00167-020-06053-x
    Improved implant position and lower revision rate with robotic-assisted unicompartmental knee arthroplasty. Batailler Cécile,White Nathan,Ranaldi Filippo Maria,Neyret Philippe,Servien Elvire,Lustig Sébastien Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The aim of this case-control study was to compare implant position and revision rate for UKA, performed with either a robotic-assisted system or with conventional technique. METHODS:Eighty UKA (57 medial, 23 lateral) were performed with robotic assistance (BlueBelt Navio system) between 2013 and 2017. These patients were matched with 80 patients undergoing UKA using the same prosthesis, implanted using conventional technique. The sagittal and coronal component position was assessed on postoperative radiographs. The revision rate was reported at last follow-up. RESULTS:The mean follow-up was 19.7 months ± 9 for the robotic-assisted group, and 24.2 months ± 16 for the control group. The rate of postoperative limb alignment outliers (± 2°) was significantly higher in the control group than in the robotic-assisted group for both lateral UKA (26% in robotic group versus 61% in control group; p = 0.018) and medial UKA (16% versus 32%, resp.; p = 0.038). The coronal and sagittal tibial baseplate position had significantly less outliers (± 3°) in the robotic-assisted group, than in the control group. Revision rates were: 5% (n = 4/80) for robotic assisted UKA and 9% (n = 7/80) for conventional UKA (n.s.). The reasons for revision were different between groups, with 86% of revisions in the control group occurring in association with component malposition or limb malalignment, compared with none in the robotic-assisted group. CONCLUSION:Robotic-assisted UKA has a lower rate of postoperative limb alignment outliers, as well as a lower revision rate, compared to conventional technique. The accuracy of implant positioning is improved by this robotic-assisted system. LEVEL OF EVIDENCE:Level of evidence III. Retrospective case-control study CLINICAL RELEVANCE: This is the first paper comparing implant position, clinical outcome, and revision rate for UKA performed using the Navio robotic system with a control group. 10.1007/s00167-018-5081-5
    Revision Risk for Total Knee Arthroplasty Converted from Medial Unicompartmental Knee Arthroplasty: Comparison with Primary and Revision Arthroplasties, Based on Mid-Term Results from the Danish Knee Arthroplasty Registry. El-Galaly Anders,Kappel Andreas,Nielsen Poul Torben,Jensen Steen Lund The Journal of bone and joint surgery. American volume BACKGROUND:Medial unicompartmental knee arthroplasties (UKAs) have good clinical outcomes but implant survival is inferior to that of total knee arthroplasties (TKAs). Conversion to a TKA is a reliable option when UKA fails. However, there is controversy regarding these conversions. The aim of this study was to analyze the survival of TKAs converted from UKAs when compared with both primary and revision TKAs. METHODS:On the basis of registrations in the Danish Knee Arthroplasty Registry from 1997 to 2017, 1,012 TKAs converted from UKAs were compared with 73,819 primary TKAs and 2,572 revision TKAs. The primary outcome was the risk of revision. Secondarily, the study analyzed the influence of different implants, the indication for the UKA conversion, and surgical volume on the survival of TKA converted from UKA. Third, the study compared the indications for revision. RESULTS:The converted UKAs were mainly mobile-bearing (85%) and, at the time of conversion, the patients were younger (mean [standard deviation], 66 ± 10 years) and more were Charnley class A (55%) compared with patients with primary TKA (70 ± 9 years and 35% class A) or revision TKA (70 ± 10 years and 42% class A) (all p < 0.001). The survival of TKAs converted from UKAs was comparable with that of revision TKAs (p = 0.42) and significantly inferior to the survival of primary TKAs (p < 0.001). This relationship was unaffected by differences between the groups, with an adjusted hazard ratio of 0.94 (95% confidence interval [CI]: 0.74 to 1.19) compared with revision TKAs and 3.00 (95% CI: 2.47 to 3.66) compared with primary TKAs. The survival of TKA converted from UKA was unaffected by differences in the conversion implants (all p ≥ 0.47), experience with revision surgery (all p ≥ 0.06), and the indications for the UKA-to-TKA conversion (all p ≥ 0.27). Instability (26%) and unexplained pain (13%) were more frequent indications for revisions of TKA converted from UKA (p < 0.001). CONCLUSIONS:TKA converted from medial UKA has a 3-fold higher risk of revision when compared with primary TKA. The implant survival resembled that of revision TKA but with a higher prevalence of unexplained pain and instability. LEVEL OF EVIDENCE:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. 10.2106/JBJS.18.01468
    Comparison of Fixed-Bearing and Mobile-Bearing Unicompartmental Knee Arthroplasty: A Systematic Review and Meta-Analysis. Cao ZhenWu,Niu CaiLi,Gong ChunZhu,Sun Yong,Xie JunHui,Song YueLi The Journal of arthroplasty BACKGROUND:Prior studies have compared fixed-bearing unicompartmental knee arthroplasty (FB-UKA) with mobile-bearing UKA (MB-UKA), suggesting that both procedures have good clinical outcomes. However, which treatment is more beneficial for patients is controversial. The purpose of our study is to evaluate the postoperative outcomes, including the revision rate, complications, functional results, range of motion, and femoral-tibial angle, between the 2 procedures. METHODS:We searched the MEDLINE, EMBASE, Cochrane Library, and Web of Science databases starting from August 2017 to May 2018. The publication date of articles was not restricted. Before we submit our contribution, we have re-searched it again. Articles that directly compared the postoperative outcomes of the 2 prosthesis type were included. RESULTS:A total of 15 comparative studies were included in our meta-analysis. The pooled data indicated no differences between the 2 operation modes in terms of revision rates, complications, and knee function, but earlier failure occurred more frequently with the MB design. CONCLUSION:Both the arthroplasty types provided satisfactory clinical results for patients with classic indications. However, MB-UKA tended to fail in early postoperative years whereas fixed-bearing UKA in later postoperative years. Therefore treatment options should be carefully considered for each patient, and surgeons should still use their personal experience when deciding between these options. 10.1016/j.arth.2019.07.005
    The learning curve associated with robotic-arm assisted unicompartmental knee arthroplasty: a prospective cohort study. Kayani B,Konan S,Pietrzak J R T,Huq S S,Tahmassebi J,Haddad F S The bone & joint journal Aims:The primary aim of this study was to determine the surgical team's learning curve for introducing robotic-arm assisted unicompartmental knee arthroplasty (UKA) into routine surgical practice. The secondary objective was to compare accuracy of implant positioning in conventional jig-based UKA versus robotic-arm assisted UKA. Patients and Methods:This prospective single-surgeon cohort study included 60 consecutive conventional jig-based UKAs compared with 60 consecutive robotic-arm assisted UKAs for medial compartment knee osteoarthritis. Patients undergoing conventional UKA and robotic-arm assisted UKA were well-matched for baseline characteristics including a mean age of 65.5 years (sd 6.8) vs 64.1 years (sd 8.7), (p = 0.31); a mean body mass index of 27.2 kg.m2 (sd 2.7) vs 28.1 kg.m2 (sd 4.5), (p = 0.25); and gender (27 males: 33 females vs 26 males: 34 females, p = 0.85). Surrogate measures of the learning curve were prospectively collected. These included operative times, the Spielberger State-Trait Anxiety Inventory (STAI) questionnaire to assess preoperative stress levels amongst the surgical team, accuracy of implant positioning, limb alignment, and postoperative complications. Results:Robotic-arm assisted UKA was associated with a learning curve of six cases for operating time (p < 0.001) and surgical team confidence levels (p < 0.001). Cumulative robotic experience did not affect accuracy of implant positioning (p = 0.52), posterior condylar offset ratio (p = 0.71), posterior tibial slope (p = 0.68), native joint line preservation (p = 0.55), and postoperative limb alignment (p = 0.65). Robotic-arm assisted UKA improved accuracy of femoral (p < 0.001) and tibial (p < 0.001) implant positioning with no additional risk of postoperative complications compared to conventional jig-based UKA. Conclusion:Robotic-arm assisted UKA was associated with a learning curve of six cases for operating time and surgical team confidence levels but no learning curve for accuracy of implant positioning. Cite this article: Bone Joint J 2018;100-B:1033-42. 10.1302/0301-620X.100B8.BJJ-2018-0040.R1
    Anterior Cruciate Ligament Deficiency is Not Always a Contraindication for Medial Unicompartmental Knee Arthroplasty: A Retrospective Study in Nondesigner's Japanese Hospital. Kikuchi Kenichi,Hiranaka Takafumi,Kamenaga Tomoyuki,Hida Yuichi,Fujishiro Takaaki,Okamoto Koji The Journal of arthroplasty BACKGROUND:An intact anterior cruciate ligament (ACL) is thought to be prerequisite for successful unicompartmental knee arthroplasty (UKA), but recent studies reported successful midterm results of UKA in ACL-deficient (ACLD) knees. We hypothesized that ACLD is not always a contraindication for medial UKA when preoperative radiographs showed typical anteromedial knee patterns. METHODS:From April 2012 to March 2016, 401 Oxford mobile-bearing UKAs in 282 patients were retrospectively identified from our database. Patients whose ACL was severely damaged, but preoperative X-rays showed typical anteromedial osteoarthritis patterns, were categorized into the ACLD group. From intraoperative data, those whose ACL was intact were categorized into the ACL functional (ACLF) group. There were 32 and 369 knees in the ACLD and ACLF groups, respectively, and mean follow-up periods were 66.1 and 63.8 months for the ACLD and ACLF groups, respectively. We compared the postoperative clinical outcome and component survivorship, with an endpoint of component revision, between ACLD groups and ACLF groups. RESULTS:In both groups, the Oxford knee score, Knee Society score, Tegner activity score, and knee range of motion in extension were improved after surgery. The UKA component survival rate at five years was 100% in the ACLD group and 98.9% in the ACLF group. There were no significant differences between the groups. CONCLUSION:Mid-term clinical outcomes of Oxford mobile-bearing UKA in ACLD knees were similar to those in ACLF knees. ACL deficiency is not always a contraindication for medial unicompartmental knee arthroplasty in patients with typical anteromedial osteoarthritis radiographs. 10.1016/j.arth.2020.08.024
    Revision Risk for Total Knee Arthroplasty Converted from Medial Unicompartmental Knee Arthroplasty: Comparison with Primary and Revision Arthroplasties, Based on Mid-Term Results from the Danish Knee Arthroplasty Registry. El-Galaly Anders,Kappel Andreas,Nielsen Poul Torben,Jensen Steen Lund The Journal of bone and joint surgery. American volume BACKGROUND:Medial unicompartmental knee arthroplasties (UKAs) have good clinical outcomes but implant survival is inferior to that of total knee arthroplasties (TKAs). Conversion to a TKA is a reliable option when UKA fails. However, there is controversy regarding these conversions. The aim of this study was to analyze the survival of TKAs converted from UKAs when compared with both primary and revision TKAs. METHODS:On the basis of registrations in the Danish Knee Arthroplasty Registry from 1997 to 2017, 1,012 TKAs converted from UKAs were compared with 73,819 primary TKAs and 2,572 revision TKAs. The primary outcome was the risk of revision. Secondarily, the study analyzed the influence of different implants, the indication for the UKA conversion, and surgical volume on the survival of TKA converted from UKA. Third, the study compared the indications for revision. RESULTS:The converted UKAs were mainly mobile-bearing (85%) and, at the time of conversion, the patients were younger (mean [standard deviation], 66 ± 10 years) and more were Charnley class A (55%) compared with patients with primary TKA (70 ± 9 years and 35% class A) or revision TKA (70 ± 10 years and 42% class A) (all p < 0.001). The survival of TKAs converted from UKAs was comparable with that of revision TKAs (p = 0.42) and significantly inferior to the survival of primary TKAs (p < 0.001). This relationship was unaffected by differences between the groups, with an adjusted hazard ratio of 0.94 (95% confidence interval [CI]: 0.74 to 1.19) compared with revision TKAs and 3.00 (95% CI: 2.47 to 3.66) compared with primary TKAs. The survival of TKA converted from UKA was unaffected by differences in the conversion implants (all p ≥ 0.47), experience with revision surgery (all p ≥ 0.06), and the indications for the UKA-to-TKA conversion (all p ≥ 0.27). Instability (26%) and unexplained pain (13%) were more frequent indications for revisions of TKA converted from UKA (p < 0.001). CONCLUSIONS:TKA converted from medial UKA has a 3-fold higher risk of revision when compared with primary TKA. The implant survival resembled that of revision TKA but with a higher prevalence of unexplained pain and instability. LEVEL OF EVIDENCE:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence. 10.2106/JBJS.18.01468
    Equal tibial component fixation of a mobile-bearing and fixed-bearing medial unicompartmental knee arthroplasty: a randomized controlled RSA study with 2-year follow-up. Koppens Daan,Rytter Søren,Munk Stig,Dalsgaard Jesper,Sørensen Ole G,Hansen Torben B,Stilling Maiken Acta orthopaedica Background and purpose - Differences in stress distribution in a mobile-bearing and fixed-bearing unicompartmental knee arthroplasty (UKA) design might lead to a difference in fixation of the tibial component. We compared tibial component migration of a mobile-bearing (MB) UKA and a fixed-bearing (FB) UKA using radiostereometric analysis.Patients and methods - In a randomized, patient-blinded clinical trial 62 patients received either the MB Oxford UKA or the FB Sigma UKA. The patients were followed for 24 months with radiostereometric analysis. Clinical outcome was assessed with Oxford Knee Score (OKS), RAND-36 and leg extension power.Results - Migration of the tibial components was similar between groups throughout follow-up. At 12 months, MTPM of the tibial component was 0.44 mm (95% CI 0.34-0.55) for the MB group and 0.40 mm (CI 0.31-0.50) for the FB group. Between 12 and 24 months, the tibial components migrated with a median MTPM increase of 0.03 mm (CI -0.02 to 0.08) in the MB group and 0.03 mm (CI -0.02 to 0.07) in the FB group. Continuous migration of the tibial component was found for 1 MB UKA and 2 FB UKAs. Both groups showed similar and clinically relevant improvement in clinical outcome.Interpretation - MB and FB tibial components had similar good fixation and clinical improvement until 2 years. Based on this study, a low 5- to 10-year revision rate can be expected for both implants. 10.1080/17453674.2019.1639965
    The forgotten joint score in total and unicompartmental knee arthroplasty: a prospective cohort study. Peersman Geert,Verhaegen Jeroen,Favier Barbara International orthopaedics PURPOSE:The purpose of this study was to assess whether unicompartmental knee arthroplasty (UKA) results in better patient-reported and clinical outcome than total knee arthroplasty (TKA). The study hypothesis was UKA yields better patient-reported and clinical outcomes than TKA. METHODS:Our prospective cohort study compared patients who underwent medial UKA or TKA from February 2014 through June 2015. Forgotten Joint Score (FJS), the short form of the Knee Injury and Osteoarthritis Outcome Score (KOOS PS), EuroQOL Five Dimensions Questionnaire (EQ-5D), and the Knee Society Score (KSS) were completed at two weeks, six weeks, three months, six months, and one year post-operatively. The KOOS PS, EQ-5D, and the KSS were also documented pre-operatively. RESULTS:Fifty-seven patients (57 knees) were allocated to the UKA group and 62 patients (62 knees) to the TKA group. At baseline, no statistically significant differences were observed between groups regarding patient demographics and pre-operative scores. Except for FJS at 2 weeks (p = 0.326), all postoperative scores revealed significant differences as early as two weeks and up to 12 months (p < 0.05). CONCLUSIONS:Our findings suggest UKA patients are less aware of their joint replacements than TKA patients for medial osteoarthritis of the knee. UKA conserves more soft tissue and bone than TKA, which may be the reason for the differences observed. 10.1007/s00264-019-04342-w
    Comparison of robotic-assisted versus conventional unicompartmental knee arthroplasty for the treatment of single compartment knee osteoarthritis: A meta-analysis. Zhang Pei,Xu Keteng,Zhang Jiale,Chen Pengtao,Fang Yongchao,Wang Jingcheng The international journal of medical robotics + computer assisted surgery : MRCAS BACKGROUND:The robotic-assisted unicompartmental knee arthroplasty (UKA) is proposed to improve the accuracy of component positioning. METHODS:We conducted a literature search in Medline, Embase, Web of Science and the Cochrane Library until April 2020. RESULTS:Our meta-analysis included 10 articles, involving 1231 knees. Our meta-analysis demonstrated that the robotic group had significantly better results in outliers of limb alignment (p < 0.001) and outliers of tibial alignment (p < 0.001). No statistical differences were found in the American Knee Society Score (p = 0.63), range of motion (p = 0.93), pain (p = 0.27), rate of revisions (p = 0.73) and rate of complications (p = 0.67). CONCLUSIONS:Robotic-assisted UKA has better component position accuracy compared with conventional UKA. But there was no significant difference in clinical results. In order to further evaluate the utility of robotic-assisted UKA, long-term follow-up randomized controlled trials (RCTs) are needed, as well as studies to evaluate the correlation between postoperative alignment and long-term clinical results. 10.1002/rcs.2170
    Robot-assisted unicompartmental knee arthroplasty for patients with isolated medial compartment osteoarthritis is cost-effective: a markov decision analysis. Clement Nick D,Deehan David J,Patton James T The bone & joint journal AIMS:The primary aim of the study was to perform an analysis to identify the cost per quality-adjusted life-year (QALY) of robot-assisted unicompartmental knee arthroplasty (rUKA) relative to manual total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) for patients with isolated medial compartment osteoarthritis (OA) of the knee. Secondary aims were to assess how case volume and length of hospital stay influenced the relative cost per QALY. PATIENTS AND METHODS:A Markov decision analysis was performed, using known parameters for costs, outcomes, implant survival, and mortality, to assess the cost-effectiveness of rUKA relative to manual TKA and UKA for patients with isolated medial compartment OA of the knee with a mean age of 65 years. The influence of case volume and shorter hospital stay were assessed. RESULTS:Using a model with an annual case volume of 100 patients, the cost per QALY of rUKA was £1395 and £1170 relative to TKA and UKA, respectively. The cost per QALY was influenced by case volume: a low-volume centre performing ten cases per year would achieve a cost per QALY of £7170 and £8604 relative to TKA and UKA. For a high-volume centre performing 200 rUKAs per year with a mean two-day length of stay, the cost per QALY would be £648; if performed as day-cases, the cost would be reduced to £364 relative to TKA. For a high-volume centre performing 200 rUKAs per year with a shorter length of stay of one day relative to manual UKA, the cost per QALY would be £574. CONCLUSION:rUKA is a cost-effective alternative to manual TKA and UKA for patients with isolated medial compartment OA of the knee. The cost per QALY of rUKA decreased with reducing length of hospital stay and with increasing case volume, compared with TKA and UKA. Cite this article: 2019;101-B:1063-1070. 10.1302/0301-620X.101B9.BJJ-2018-1658.R1
    Unicompartmental knee arthroplasty has higher revisions than total knee arthroplasty at long term follow-up: a registry study on 6453 prostheses. Di Martino A,Bordini B,Barile F,Ancarani C,Digennaro V,Faldini C Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The purpose of this study is to analyse long-term unicompartmental knee arthroplasty (UKA) focusing on survivorship, causes of failure and revision strategy. METHODS:This study is a retrospective analysis of data from a regional arthroplasty registry for cases performed between 2000 and 2017. A total of 6453 UKAs were identified and the following information was analysed: demographic data, diagnosis leading to primary implant, survivorship, complication rate, causes of failure, revision strategies. UKA registry data were compared with total knee arthroplasty (TKA) registry data of 54,012 prostheses, which were implanted in the same time period. RESULTS:6453 UKAs were included in the study: the vast majority of them (84.4%) were implanted due to primary osteoarthritis followed by deformity (7.1%) and necrosis of the condyle (5.1%). When compared to TKA, UKA showed lower perioperative complication rate (0.3% compared to 0.6%) but higher revision rate (18.2% at 15 years, compared to 6.2% for TKA). No correlation was found between diagnosis leading to primary implant and prosthesis survival. The most frequent cause of failure was total aseptic loosening (37.4%), followed by pain without loosening (19.8%). Of the 620 UKAs requiring revision, 485 were revised with a TKA and 61 of them required a re-revision; on the other hand, of the 35 cases where another UKA was implanted, 16 required a re-revision. CONCLUSION:UKA is associated with fewer perioperative complications but higher revision rates when compared to TKA. Its survivorship is not affected by the diagnosis leading to primary implant. Revision surgery of a failed UKA should be performed implanting a TKA, which is associated with a lower re-revision rate when compared to another UKA. LEVEL OF EVIDENCE:Level 3, therapeutic study. 10.1007/s00167-020-06184-1
    A systematic review of imageless hand-held robotic-assisted knee arthroplasty: learning curve, accuracy, functional outcome and survivorship. Clement Nicholas D,Al-Zibari Marwan,Afzal Irrum,Deehan David J,Kader Deiary EFORT open reviews The aim of this systematic review was to present and assess the quality of evidence for learning curve, component positioning, functional outcomes and implant survivorship for imagefree hand-held roboticassisted knee arthroplasty.Searches of PubMed and Google Scholar were performed in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. The criteria for inclusion was any published fulltext article or abstract assessing imagefree hand-held robotic knee arthroplasty and reporting learning curve, implant positioning, functional outcome or implant survival for clinical or non-clinical studies.There were 22 studies included. Five studies reported the learning curve: all were for unicompartmental knee arthroplasty (UKA) - no learning curve for accuracy, operative time was reduced after five to 10 cases and a steady surgical time was achieved after eight cases.There were 16 studies reporting accuracy: rate of outliers was halved, higher rate of joint line and mechanical axis restoration, supported by low root mean square error values.Six studies reported functional outcome: all for UKA, improvement at six to 52 weeks, no difference from manual UKA except when assessed for lateral UKA which showed improved clinical outcomes.Two studies reported survivorship: one reported an unadjusted revision rate of 7% at 20 months for medial UKA and the other found a 99% two-year survival rate for UKA.There was evidence to support more accurate implant positioning for UKA, but whether this is related to superior functional outcomes or improved implant survivorship was not clear and further studies are required. Cite this article: 2020;5:319-326. DOI: 10.1302/2058-5241.5.190065. 10.1302/2058-5241.5.190065
    High Failure Rates for Unicompartmental Knee Arthroplasty in Morbidly Obese Patients: A Two-Year Minimum Follow-Up Study. Nettrour John F,Ellis Robert T,Hansen Benjamin J,Keeney James A The Journal of arthroplasty BACKGROUND:Several recent studies have recommended offering unicompartmental knee arthroplasty (UKA) to all patients regardless of body mass index (BMI). The aim of this investigation was to evaluate the proposition that UKA can indeed be offered to the morbidly-obese and super-obese (morbidly-obese, BMI ≥ 40 kg/m) without compromising results or survivorship. METHODS:We retrospectively reviewed mobile-bearing medial UKA procedures performed at our facility from January 2012 to May 2015 with a minimum of 2-year follow-up. The study cohort was divided into patients with morbid obesity (BMI ≥ 40 kg/m) and those without morbid obesity (BMI < 40 kg/m). A detailed medical record review was performed. Extracted outcome data included the frequency of (1) major revision procedures (components revised), (2) minor secondary procedures (components not revised), (3) infection procedures, and (4) recommendations for revision. RESULTS:We found 152 patients (190 knees) who met criteria for inclusion. Mean follow-up duration was 3.4 years (range: 2.0-6.8 years). Major revision surgery occurred more frequently in the morbid-obesity UKA group (15.7% vs 3.0%, P < .01). Rates of minor secondary surgery and infection were comparable for both groups. Most failures in the morbid-obesity UKA group (85.7%) were due to disease progression involving other compartments or mobile-bearing instability. CONCLUSION:We found the rate of early major revision surgery in morbidly-obese patients undergoing UKA to be over 5-times greater than that of other patients. Failure was predominantly due to disease progression in other compartments or mobile-bearing instability. Further study is warranted and needed before expanding UKA indications to the morbidly-obese population. 10.1016/j.arth.2019.11.003
    Unicompartmental Knee Arthroplasty Provides Significantly Greater Improvement in Function than Total Knee Arthroplasty Despite Equivalent Satisfaction for Isolated Medial Compartment Osteoarthritis. Casper David S,Fleischman Andrew N,Papas Paraskevi Vivian,Grossman Jamie,Scuderi Giles R,Lonner Jess H The Journal of arthroplasty BACKGROUND:While some advocate for unicompartmental knee arthroplasty (UKA) for isolated medial compartment osteoarthritis (OA), others favor total knee arthroplasty (TKA). The purpose of this study was to compare the functional outcomes of UKA and TKA performed for patients with unicompartmental arthritis (OA). METHODS:A study was performed on 133 patients that met strict criteria for UKA, but who underwent either medial UKA or TKA for isolated medial compartment OA based upon physician equipoise. The primary outcome-New Knee Society Score (KSS)-was assessed preoperatively and at 2 years postoperatively. A propensity score weighted regression was used to balance the groups on several key covariates, including age, gender, body mass index, and baseline KSS. RESULTS:After propensity weighting, there were no significant differences between UKA and TKA in overall baseline KSS or KSS after 2 years postoperatively. While TKA patients had demonstrated a significantly greater improvement in the symptoms KSS subscale, UKA patients had a significantly greater improvement in the function subscale. Expectations were significantly more likely to be met after UKA, but there were no differences in patient satisfaction. CONCLUSION:UKA and TKA are both highly successful options for treating patients with medial compartment OA, although functionality increased more, and expectations were more likely to be met, after UKA in this study. Given equivalent patient satisfaction after both TKA and UKA, surgeons should consider factors such as clinical experience, individual preference, cost of care, surgical risk, and recovery needs, when making treatment decisions regarding this clinical entity. 10.1016/j.arth.2019.04.005
    Patients return to work sooner after unicompartmental knee arthroplasty than after total knee arthroplasty. Kievit Arthur J,Kuijer P Paul F M,de Haan Laurens J,Koenraadt Koen L M,Kerkhoffs Gino M M J,Schafroth Matthias U,van Geenen Rutger C I Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:It is not yet known if unicompartmental knee arthroplasty (UKA) patients are more likely to return to work sooner or have improved ability to work (i.e., workability) than total knee arthroplasty (TKA) patients. The following questions were addressed: patients were assessed to determine: (1) whether they returned to work sooner following UKA compared to TKA; (2) whether UKA patients had better WORQ function scores compared to TKA patients; and (3) if UKA patients have higher workability scores and greater satisfaction regarding workability than TKA patients. METHODS:A multicenter retrospective cohort study was performed that included patients at least 2 years after having undergone either UKA or TKA surgery and on the condition that patients had been in work in the 2 years prior to surgery. Time period between stopping work and returning to work was assessed; the WORQ scores (0 = worst-100 = best) and the Work Ability Index (WAI = 0-10) and reported satisfaction with work ability. RESULTS:UKA patients (n = 157, median 60 years, 51% male) were compared to TKA patients (n = 167, median 60 years, 49% male) (n.s.). Of the 157 UKA patients, 115 (73%) returned to work within 2 years compared to 121 (72%) of TKA patients (n.s.). More UKA patients return to work within 3 months (73% versus 48%) (p < 0.01). WORQ scores improved similarly in both groups. The WAI was also comparable between the groups. Dissatisfaction with workability was comparable (UKA 15% versus TKA 18% (n.s.). CONCLUSION:TKA and UKA patients have similar WORQ, WAI, and satisfaction scores. However, in this study population, UKA patients to return to work after surgery significantly sooner than TKA patients, which improves their quality of life and allows them to participate actively in society. This information can help health care providers and patients weigh-up the pros and cons and choose the best treatment and timing for patients in the working population. LEVEL OF EVIDENCE:III. 10.1007/s00167-019-05667-0
    Medial unicompartmental knee arthroplasty in ACL-deficient knees is a viable treatment option: in vivo kinematic evaluation using a moving fluoroscope. Zumbrunn Thomas,Schütz Pascal,von Knoch Fabian,Preiss Stefan,List Renate,Ferguson Stephen J Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Unicompartmental knee arthroplasty (UKA), resulting in similar kinematics to native knees, is functionally superior to total knee arthroplasty (TKA). However, ACL deficiency is generally considered to be a contraindication. The main purpose of this study was to investigate if UKA in ACL-deficient knees would result in similar kinematics to conventional UKA with an intact ACL. METHODS:Ten conventional UKA patients were compared to eight ACL-deficient patients with a reduced tibial slope to compensate for instability, resulting from the deficient ACL. Knee kinematics was evaluated with a moving fluoroscope, tracking the knee joint during daily activities. In a standing position (baseline), posterior shift of the femur was observed for ACL-deficient UKA patients, compared to conventional UKA patients. RESULTS:A significant posterior femoral shift in the ACL-deficient group was observed during the first 25% (near extension) of deep knee bend, while there was no difference in kinematic waveforms for all other activities. No significant range of motion differences across different activities between the two UKA groups were detected, except for an increase of medial AP translation in the ACL-deficient group, during deep knee bend and stair descent. CONCLUSION:Despite the posterior femoral shift due to ACL deficiency, both UKA groups showed similar kinematic waveforms, indicating that posterior tibial slope reduction can partially compensate for ACL function. This supported our hypothesis that fixed bearing UKA can be a viable treatment option for selected ACL-deficient patients, allowing patient-specific kinematics. While anteroposterior laxity can be compensated, rotational stability was a prerequisite for this approach. LEVEL OF EVIDENCE:III. 10.1007/s00167-019-05594-0
    Similar polyethylene wear between cemented and cementless Oxford medial UKA: a 5-year follow-up randomized controlled trial on 79 patients using radiostereometry. Horsager Kristian,Madsen Frank,Odgaard Anders,Fink Jepsen Claus,Rømer Lone,Kristensen Per Wagner,Kaptein Bart L,Søballe Kjeld,Stilling Maiken Acta orthopaedica Background and purpose - Hydroxyapatite (HA)-coated implants have been associated with high polyethylene wear in hip arthroplasties. HA coating as a promoter of wear in knee arthroplasties has not been investigated. We compared the wear-rate of the polyethylene bearing for cemented and cementless HA-coated Oxford medial unicondylar knee arthroplasties (UKA). Secondarily, we investigated whether wear-rates were influenced by overhang or impingement of the bearing. Patients and methods - 80 patients (mean age 64 years), treatment-blinded, were randomized to 1 of 3 Oxford medial UKA versions: cemented with double-pegged or single-pegged femoral component or cementless HA-coated with double-pegged femoral component (ratios 1:1:1). We compared wear between the cemented (n = 55) and cementless group (n = 25) (ratio 2:1). Wear, impingement, and overhang were quantified between surgery and 5-year follow-up using radiostereometry. Clinical outcome was evaluated with the Oxford Knee Score. Results - The mean wear-rate for patients without bearing overhang was 0.04 mm/year (95% CI 0.02-0.07) for the cemented group and 0.05 mm/year (CI 0.02-0.08) for the cementless group. The mean difference in wear was 0.008 mm/year (CI -0.04 to 0.03). No impingement was identified. Half of the patients had medial bearing overhang, mean 2.5 mm (1-5). Wear increased by 0.014 mm/year for each mm increment in overhang. The mean Oxford Knee Score was 39 for the cementless group and 38 for the cemented group at the 5-year follow-up. Interpretation - The wear-rates were similar for the 2 fixation methods, which supports further use of the cementless Oxford medial UKA. However, a caveat is a relatively large 95% CI of the mean difference in wear-rate. Component size and position is important as half of the patients presented with an additional increase in wear-rate due to medial bearing overhang. 10.1080/17453674.2018.1543757
    Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA. Inoue Atsuo,Arai Yuji,Nakagawa Shuji,Inoue Hiroaki,Yamazoe Shoichi,Kubo Toshikazu The Journal of arthroplasty Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. 10.1016/j.arth.2015.07.024
    Is ACL deficiency always a contraindication for medial UKA? Kinematic and kinetic analysis of implanted and contralateral knees. Suter Lorena,Roth Adrian,Angst Michael,von Knoch Fabian,Preiss Stefan,List Renate,Ferguson Stephen,Zumbrunn Thomas Gait & posture BACKGROUND:Prevalence of knee osteoarthritis increases because life expectancy continues to rise with an active patient population. Hence, the concept of unicompartmental knee arthroplasty (UKA) has regained popularity as a treatment option for unicompartmental knee osteoarthritis. Anterior cruciate ligament (ACL) deficiency is widely considered as a contraindication for UKA, however, there are conflicting reports. If otherwise indicated, some surgeons consider UKA for ACL-deficient patients using a modified surgical technique, with a reduction of posterior tibial slope. RESEARCH QUESTION:The purpose of this study was to evaluate outcomes in UKA patients with ACL deficiency in comparison to a conventional UKA group (intact ACL) by the measurement of knee kinematics and kinetics. METHODS:Ten patients with conventional UKA and an intact ACL and eight patients with an ACL-deficient UKA and a reduced posterior tibial slope relative to the native knee were recruited. Three-dimensional joint kinematics of the knee were measured, using skin markers and an infrared optical motion capture system. Ground reaction forces (GRF) were measured with force plates in all three directions. Level walking, ramp descent and stair descent were analyzed, comparing implanted and contralateral native knees and the two UKA groups. RESULTS:No significant differences in kinetics and kinematics were observed between conventional UKA and ACL-deficient UKA groups for any of the activities. However, some asymmetries in GRF between the implanted and contralateral side were present for the ACL-deficient group, during level walking (unloading rate) and stair descent (stance time). SIGNIFICANCE:Promising outcomes of the ACL-deficient UKA group suggest that ACL deficiency may not always be a contraindication. Therefore, ACL-deficient UKA could be an alternative treatment option to total knee arthroplasty for an appropriate surgeon selected patient population. 10.1016/j.gaitpost.2018.11.031
    Bicruciate-retaining total knee arthroplasty reproduces in vivo kinematics of normal knees to a lower extent than unicompartmental knee arthroplasty. Kono Kenichi,Inui Hiroshi,Tomita Tetsuya,Yamazaki Takaharu,Taketomi Shuji,Tanaka Sakae Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:This study aimed to clarify the natural knee kinematics provided by bicruciate-retaining total knee arthroplasty (BCR-TKA) compared with those of unicompartmental knee arthroplasty (UKA) and normal knees. METHODS:Volunteers and patients who had undergone UKA and BCR-TKA with anatomical articular surface performed squatting motion under fluoroscopy. To estimate the knee's spatial position and orientation, a two-dimensional/three-dimensional registration technique was used. The rotation angle and anteroposterior translation of the medial and lateral sides of the femur relative to the tibia in each flexion angle were directly evaluated using the same local coordinate system and their differences amongst the three groups were analysed using two-way analysis of variance and Bonferroni post hoc pairwise comparison. RESULTS:From 0° to 10° of flexion, the femoral external rotation angle of BCR-TKA knees was significantly greater than that of normal and UKA knees and the medial side of BCR-TKA knees was significantly more anteriorly located than that of normal and UKA knees. From 40° to 50° of flexion, the medial side of UKA knees was significantly more posteriorly located than that of normal and BCR-TKA knees. From 30° to 120° of flexion, the lateral side of BCR-TKA knees was significantly more anteriorly located than that of normal and UKA knees. CONCLUSION:The in vivo kinematics of BCR-TKA knees reproduces those of normal knees to a lower extent than those of UKA knees. Thus, BCR-TKA with anatomical articular surface reproduces in vivo kinematics of normal knees to a lower extent than UKA. LEVEL OF EVIDENCE:III. 10.1007/s00167-019-05754-2
    The patient results and satisfaction of knee arthroplasty in a validated grading system. Oosthuizen Christiaan Rudolf,Van Der Straeten Catherine,Maposa Innocent,Snyckers Christian Hugo,Vermaak Duwayne Peter,Magobotha Sebastian International orthopaedics INTRODUCTION:The validated Knee Osteoarthritis Grading System (KOGS) was implemented and clinical results were compared with patient satisfaction data and implant survivorship in a multi-centre study with surgeons familiar with unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA). This is also the first study to evaluate the prevalence of UKA and TKA in consecutive osteoarthritis (OA) knee arthroplasties assessed by this system.. METHOD:A consecutive cohort of knees was gathered at three different institutions as categorized by KOGS and surgically treated with the recommended implant unless clinical reasons or patient preference precluded such an option. One thousand one hundred seventy-seven consecutive knees were evaluated including 311 TKA (26%), 695 medial UKA (59%), 154 lateral UKA (13%) and 17 PFA (2%) and the results of the categories evaluated with the Oxford Knee Score (OKS) and the complications reflected in the different categories. RESULTS:The failure rate of the UKA (3.5%) or TKA (1.6%) is not higher than accepted results in the literature and the difference in complications is negligible between the UKA (72%) and TKA (26%) cohorts. Revision of a UKA to a TKA as an endpoint was 0.58% with ipsilateral progression at 0.8% over a period of five to 84 months (mean follow-up of 36 months) despite the 'excessive' proportion of UKA in this cohort. The Oxford Score improvement is significant in TKA and UKA and contributes to the acceptable outcomes (The OKS for TKA improved from 20 pre-operatively to 36 post-operatively and the UKA improved from 22 pre-operatively to 39 post-operatively). CONCLUSION:KOGS achieves acceptable early survival and functional results when implemented and is a suitable tool for identifying the preferred implant as was validated. 10.1007/s00264-019-04412-z
    Return to Physical Activity After High Tibial Osteotomy or Unicompartmental Knee Arthroplasty: A Systematic Review and Pooling Data Analysis. Belsey James,Yasen Sam K,Jobson Simon,Faulkner James,Wilson Adrian J The American journal of sports medicine BACKGROUND:The 2 most common definitive surgical interventions currently performed for the treatment of medial osteoarthritis of the knee are medial opening wedge high tibial osteotomy (HTO) and medial unicompartmental knee arthroplasty (UKA). Research exists to suggest that physically active patients may be suitably indicated for either procedure despite HTO being historically indicated in active patients and UKA being more appropriate for sedentary individuals. PURPOSE:To help consolidate the current indications for both procedures regarding physical activity and to ensure that they are based on the best information presently available. STUDY DESIGN:Systematic review. METHODS:A search of the literature via the MEDLINE, Embase, and PubMed databases was conducted independently by 2 reviewers in accordance with the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. Studies that reported patient physical activity levels with the Tegner activity score were eligible for inclusion. Patient demographics, operative variables, and patient-reported outcome scores were abstracted from the included studies. RESULTS:Thirteen eligible studies were included, consisting of 401 knees that received HTO (399 patients) and 1622 that received UKA (1400 patients). The patients' mean age at surgery was 48.4 years for the HTO group and 60.6 years for the UKA group. Mean follow-up was 46.6 months (HTO) and 53.4 months (UKA). All outcome scores demonstrated an equal or improved score for activity and knee function regardless of the operation performed. Operative variables during HTO had a larger effect on outcome than during UKA. CONCLUSION:Patients who underwent HTO were more physically active pre- and postoperatively, but patients undergoing UKA experienced an overall greater increase in their physical activity levels and knee function according to Tegner and Lysholm scores. Activity after HTO may be influenced by operative factors such as the implant used and the decision to include a graft material in the osteotomy gap, although this requires further research. Some studies found that patients were able to return to physical activity postoperatively despite having an age or body mass index that would traditionally be a relative contraindication for HTO or UKA. 10.1177/0363546520948861
    An assessment of early functional rehabilitation and hospital discharge in conventional versus robotic-arm assisted unicompartmental knee arthroplasty: a prospective cohort study. Kayani B,Konan S,Tahmassebi J,Rowan F E,Haddad F S The bone & joint journal AIMS:The objectives of this study were to compare postoperative pain, analgesia requirements, inpatient functional rehabilitation, time to hospital discharge, and complications in patients undergoing conventional jig-based unicompartmental knee arthroplasty (UKA) versus robotic-arm assisted UKA. PATIENTS AND METHODS:This prospective cohort study included 146 patients with symptomatic medial compartment knee osteoarthritis undergoing primary UKA performed by a single surgeon. This included 73 consecutive patients undergoing conventional jig-based mobile bearing UKA, followed by 73 consecutive patients receiving robotic-arm assisted fixed bearing UKA. All surgical procedures were performed using the standard medial parapatellar approach for UKA, and all patients underwent the same postoperative rehabilitation programme. Postoperative pain scores on the numerical rating scale and opiate analgesia consumption were recorded until discharge. Time to attainment of predefined functional rehabilitation outcomes, hospital discharge, and postoperative complications were recorded by independent observers. RESULTS:Robotic-arm assisted UKA was associated with reduced postoperative pain (p < 0.001), decreased opiate analgesia requirements (p < 0.001), shorter time to straight leg raise (p < 0.001), decreased number of physiotherapy sessions (p < 0.001), and increased maximum knee flexion at discharge (p < 0.001) compared with conventional jig-based UKA. Mean time to hospital discharge was reduced in robotic UKA compared with conventional UKA (42.5 hours (sd 5.9) vs 71.1 hours (sd 14.6), respectively; p < 0.001). There was no difference in postoperative complications between the two groups within 90 days' follow-up. CONCLUSION:Robotic-arm assisted UKA was associated with decreased postoperative pain, reduced opiate analgesia requirements, improved early functional rehabilitation, and shorter time to hospital discharge compared with conventional jig-based UKA. 10.1302/0301-620X.101B1.BJJ-2018-0564.R2
    Robot-assisted unicompartmental knee arthroplasty can reduce radiologic outliers compared to conventional techniques. Park Kwan Kyu,Han Chang Dong,Yang Ick-Hwan,Lee Woo-Suk,Han Joo Hyung,Kwon Hyuck Min PloS one BACKGROUND:The aim of this study was to compare the clinical and radiologic outcomes of robot-assisted unicompartmental knee arthroplasty (UKA) to those of conventional UKA in Asian patients. METHODS:Fifty-five patients underwent robot-assisted UKA and 57 patients underwent conventional UKA were assessed in this study. Preoperative and postoperative range of motion (ROM), American Knee Society (AKS) score, Western Ontario McMaster University Osteoarthritis Index scale score (WOMAC), and patellofemoral (PF) score values were compared between the two groups. The mechanical femorotibial angle (mFTA) and Kennedy zone were also measured. Coronal alignments of the femoral and tibial components and posterior slopes of the tibial component were compared. Additionally, polyethylene (PE) liner thicknesses were compared. RESULTS:There was no significant difference between the two groups regarding postoperative ROM, AKS, WOMAC and PF score. Robot group showed fewer radiologic outliers in terms of mFTA and coronal alignment of tibial and femoral components (p = 0.022, 0.037, 0.003). The two groups showed significantly different PE liner thicknesses (8.4 ± 0.8 versus 8.8 ± 0.9, p = 0.035). Robot group was the only influencing factor for reducing radiologic outlier (postoperative mFTA) in multivariate model (odds ratio: 2.833, p = 0.037). CONCLUSION:In this study, robot-assisted UKA had many advantages over conventional UKA, such as its ability to achieve precise implant insertion and reduce radiologic outliers. Although the clinical outcomes of robot-assisted UKA over a short-term follow-up period were not significantly different compared to those of conventional UKA, longer follow-up period is needed to determine whether the improved radiologic accuracy of the components in robotic-assisted UKA will lead to better clinical outcomes and improved long-term survival. 10.1371/journal.pone.0225941
    Comparison of implant position and joint awareness between fixed- and mobile-bearing unicompartmental knee arthroplasty: a minimum of five year follow-up study. Kim Man Soo,Koh In Jun,Kim Chul Kyu,Choi Keun Young,Baek Jong Won,In Yong International orthopaedics PURPOSE:To compare the implant position and patient-reported outcomes (PROs) regarding joint awareness using the Forgotten Joint Score (FJS) following between fixed-bearing (FB) and mobile-bearing (MB) unicompartmental knee arthroplasty (UKA) with a minimum of five years' follow-up. METHODS:One hundred fifteen consecutive UKAs (58 FB UKAs and 57 MB UKAs) performed were retrospectively evaluated. We compared the radiographic parameters including component positions and relationships as well as lower extremity alignment. Post-operative clinical outcomes were assessed using Knee Society Score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Tegner activity score, and FJS. RESULTS:The MB UKA group showed more convergent componentry relationship between femoral and tibial components (p < 0.001). The joint line of the MB UKA group was restored significantly better (p < 0.05). In addition, the positioning of femoral and tibial components of the MB UKA group showed less deviation from the weight-bearing line (WBL) (p < 0.05). Although there were no differences in KSS, WOMAC, and Tegner activity scores between the groups, the MB UKA group showed significantly better FJS than did the FB UKA group at five years post-operatively (p < 0.05). CONCLUSION:The MB UKA group had a more convergent componentry relationship, less deviation from WBL, better joint-line restoration, and reduced joint awareness than did the FB UKA group at five years follow-up. 10.1007/s00264-020-04662-2
    Narcotic Consumption in Opioid Naïve Patients Undergoing Unicompartmental and Total Knee Arthroplasty. Dattilo Jonathan R,Cororaton Agnes D,Gargiulo Jeanine M,McDonald James F,Ho Henry,Hamilton William G The Journal of arthroplasty BACKGROUND:Total knee arthroplasty (TKA) is associated with increased risk of prolonged narcotic requirement compared to unicompartmental knee arthroplasty (UKA). The purpose of the current study is to compare acute postoperative narcotic consumption between the 2 procedures and quantify narcotic consumption. METHODS:From October 2017 to August 2019 patients were surveyed for four weeks to determine the amount and duration of opioids consumed and requirement for continued narcotics. Among 976 opioid naïve patients, 314 (32%) underwent UKA and 662 (68%) underwent TKA. Patients were analyzed according to specific narcotic prescribed. Total morphine equivalent dose (MED), number of pills, duration, refill percentage, and usage percentage for 4 weeks were calculated for each procedure. RESULTS:MED used in the postoperative period was lower in patients undergoing UKA than TKA (200 ± 195 vs 259 ± 250 MED, P = .002). Total number of pills consumed and duration of use was less in UKA compared to TKA regardless of which opioid was prescribed. A smaller proportion of patients required narcotics for 4 weeks after UKA (32% vs 43%, P < .001), and fewer UKA patients required narcotic refills (14% vs 27%, P < .001). Sixty pills of any 1 type of narcotic was sufficient for 90% of UKA patients and over 75% of TKA patients. CONCLUSION:UKA is associated with less narcotic consumption, shorter duration of use, less refills, and lower likelihood of narcotic requirement for 4 weeks. We report narcotic consumption patterns for both procedures to aid surgeons in judicious postoperative prescribing. LEVEL OF EVIDENCE:This is a level III retrospective cohort study reviewing narcotic use in over 900 consecutive opioid naïve patients undergoing UKA or TKA. 10.1016/j.arth.2020.03.024
    Reduced survival of total knee arthroplasty after previous unicompartmental knee arthroplasty compared with previous high tibial osteotomy: a propensity-score weighted mid-term cohort study based on 2,133 observations from the Danish Knee Arthroplasty Registry. El-Galaly Anders,Nielsen Poul T,Kappel Andreas,Jensen Steen L Acta orthopaedica Background and purpose - Both medial unicompartmental knee arthroplasties (UKA) and high tibial osteotomies (HTO) are reliable treatments for isolated medial knee osteoarthritis. However, both may with time need conversion to a total knee arthroplasty (TKA). We conducted the largest nationwide registry comparison of the survival of TKA following UKA with TKA following HTO.Patients and methods - From the Danish Knee Arthroplasty Registry, aseptic conversions to TKA from UKA and TKA converted from HTO within the period of 1997-2018 were retrieved. The Kaplan-Meier method and the Cox proportional hazards regression were used to estimate the survival and hazard ratio (HR) for revision, considering confounding by indication utilizing propensity-score based inverse probability of treatment weighting (PS-IPTW).Results - PS-IPTW yielded a well-balanced pseudo-cohort (standard mean difference (SMD) < 0.1 for all covariates, except implant supplementation) of 963.8 TKAs following UKA and 1139.1 TKAs following HTO. The survival of TKA following UKA was significantly less than that of TKA following HTO with a 5-year estimated survival of 0.88 (95% confidence interval (CI) 0.85-0.90) and 0.94 (CI 0.93-0.96), respectively. The differences in survival corresponded to an implant-supplementation adjusted HR of 2.7 (CI 2.4-3.1) for TKA following UKA compared with TKA following HTO.Interpretation - Previous UKA more than doubled the revision risk of a subsequent TKA compared with previous HTO. This potential risk should be considered in the shared treatment decision of patients who are candidates for both UKA and HTO. 10.1080/17453674.2019.1709711
    Mid-term survivorship and patient-reported outcomes of robotic-arm assisted partial knee arthroplasty. Burger Joost A,Kleeblad Laura J,Laas Niels,Pearle Andrew D The bone & joint journal AIMS:Limited evidence is available on mid-term outcomes of robotic-arm assisted (RA) partial knee arthroplasty (PKA). Therefore, the purpose of this study was to evaluate mid-term survivorship, modes of failure, and patient-reported outcomes of RA PKA. METHODS:A retrospective review of patients who underwent RA PKA between June 2007 and August 2016 was performed. Patients received a fixed-bearing medial or lateral unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA), or bicompartmental knee arthroplasty (BiKA; PFA plus medial UKA). All patients completed a questionnaire regarding revision surgery, reoperations, and level of satisfaction. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were assessed using the KOOS for Joint Replacement Junior survey. RESULTS:Mean follow-up was 4.7 years (2.0 to 10.8). Five-year survivorship of medial UKA (n = 802), lateral UKA (n = 171), and PFA/BiKA (n = 35/10) was 97.8%, 97.7%, and 93.3%, respectively. Component loosening and progression of osteoarthritis (OA) were the most common reasons for revision. Mean KOOS scores after medial UKA, lateral UKA, and PFA/BiKA were 84.3 (SD 15.9), 85.6 (SD 14.3), and 78.2 (SD 14.2), respectively. The vast majority of the patients reported high satisfaction levels after RA PKA. Subgroup analyses suggested tibial component design, body mass index (BMI), and age affects RA PKA outcomes. Five-year survivorship was 98.4% (95% confidence interval (CI) 97.2 to 99.5) for onlay medial UKA (n = 742) and 99.1% (95% CI 97.9 to 100) for onlay medial UKA in patients with a BMI < 30 kg/m (n = 479). CONCLUSION:This large single-surgeon study showed high mid-term survivorship, satisfaction levels, and functional outcomes in RA UKA using metal-backed tibial onlay components. In addition, favourable results were reported in RA PFA and BiKA. Cite this article: 2020;102-B(1):108-116. 10.1302/0301-620X.102B1.BJJ-2019-0510.R1
    Is robotic-assisted unicompartmental knee arthroplasty a safe procedure? A case control study. Mergenthaler Guillaume,Batailler Cécile,Lording Timothy,Servien Elvire,Lustig Sébastien Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:The hypotheses were that firstly there is few early specific complications due to the use of a robotic-assisted system for unicompartimental knee arthroplasty (UKA), and secondly there are less revisions and complications after robotic-assisted UKA than after conventional UKA. METHODS:200 robotic-assisted UKA (175 patients) and 191 conventional UKA (179 patients) were performed between 2013 and 2018 from the same center. Revisions, intraoperative and postoperative complications, functional and radiological results were collected at the most recent follow-up. RESULTS:At the most recent follow-up (≥ 1 year), revision rates were 4% (n = 8/200) for robotic-assisted UKA and 11% (n = 21/191) for conventional UKA (p = 0.014). Reoperation rates without implant removal were comparable in the robotic and conventional group (7.3% vs 8.6%). Complication rates for stiffness (4.7% vs 4.2%) and infection (1% vs 1.6%) were comparable in both groups. There was no specific complication related to the robotic-assisted system (no soft tissue or bone lesion caused by the use of the robotic-assistance and no complication related to the use of navigation pins). The KSS function scores were higher following robotic-assisted UKA (p = 0.01). Satisfaction rates and contralateral OA were comparable in the two groups. CONCLUSION:No complications due to the robotic-assisted system were found in this study. There was no difference in the general complications rate between both groups. Robotic-assisted UKA has a lower revision rate compared to conventional technique UKA at the short-term follow-up. LEVEL OF EVIDENCE:III. CLINICAL RELEVANCE:This is the first paper comparing revision rate and clinical outcome between UKA performed using the NAVIO robotic system and a conventional technique and searching for specific complication related to the use of the NAVIO robotic system. 10.1007/s00167-020-06051-z
    A systematic review of MAKO-assisted unicompartmental knee arthroplasty. Lin Jiyan,Yan Shigui,Ye Zhaoming,Zhao Xiang The international journal of medical robotics + computer assisted surgery : MRCAS Unicompartmental knee arthroplasty (UKA), which has many potential advantages compared with total knee arthroplasty, was widely used across the world in recent years. The introduction of the robot systems greatly makes up for the defects of the conventional UKA surgery such as higher complication rates and revision rates. MAKO system, a new image-guided robot system relies on a preoperative computed tomography scan to assist in preoperative mapping and planning, offers an opportunity to improve the outcome of UKA surgeries. In order to have a more comprehensive and in-depth understanding of MAKO-assisted UKA, the studies on MAKO-assisted UKA were summarized. MAKO-assisted UKA is better than conventional UKA surgery on implant accuracy, soft tissue balance, patient function scores and satisfaction, complications rates, and learning curve in short-term outcome; however, the mid-term and long-term outcomes of MAKO-assisted UKA need to be further studied. 10.1002/rcs.2124
    Unicompartmental knee arthroplasty, an enigma, and the ten enigmas of medial UKA. Mittal Anurag,Meshram Prashant,Kim Woo Hyun,Kim Tae Kyun Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology Unicompartmental knee arthroplasty (UKA) is a bone- and ligament-sparing alternative to total knee arthroplasty in the patients with end-stage single-compartment degeneration of the knee. Despite being a successful procedure, the multiple advantages of UKA do not correlate with its usage, most likely due to the concerns regarding prosthesis survivability, patient selection, ideal bearing design, and judicious use of advanced technology among many others. Therefore, the purpose of this study is to review and summarize the debated literature and discuss the controversies as "Ten Enigmas of UKA." 10.1186/s10195-020-00551-x
    Fixed- versus mobile-bearing UKA: a systematic review and meta-analysis. Peersman Geert,Stuyts Bart,Vandenlangenbergh Tom,Cartier Philippe,Fennema Peter Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Two design concepts are currently used for unicondylar knee arthroplasty (UKA) prostheses: fixed bearing (FB) and mobile bearing (MB). While MB prostheses have theoretical advantages over their FB counterparts, it is not clear whether they are associated with better outcomes. A systematic review was conducted to examine survivorship differences and differences in failure modes of between FB and MB designs. METHODS:PubMed, Scirus and Cochrane library databases were searched for medial UKA outcome studies. A total of 44 papers, involving 9,463 knees, were eligible. Outcomes examined included knee function, survivorship and the reasons for, and incidence of, revision for FB and MB prostheses. Random effects meta-analysis was employed to obtain pooled revision rate estimates. Where available, cause-specific time to revision was extracted. RESULTS:Mean follow-up was 8.7 years for FB and 5.9 years for MB prostheses. There were no other relevant baseline differences. The overall crude revision rate for FB and for MB prostheses was 0.90 (95 % confidence interval (CI) 0.65-1.21) and 1.51 (95 % CI 1.11-1.93) per 100 component years, respectively. After stratification on follow-up time and age, the revision rates were not substantially different, aside for younger patients in short term from studies with short-term follow-up. CONCLUSION:No essential differences between the two designs were observed. MB and FB UKA designs have comparable revision rates. As our study is based on predominantly observational data, with large variations in reporting standards, inferences should be drawn with caution. LEVEL OF EVIDENCE:IV. 10.1007/s00167-014-3131-1
    Obesity should not be considered a contraindication to medial Oxford UKA: long-term patient-reported outcomes and implant survival in 1000 knees. Molloy James,Kennedy James,Jenkins Cathy,Mellon Stephen,Dodd Christopher,Murray David Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Some health providers ration knee arthroplasty on the basis of body mass index (BMI). There is no long-term data on the outcome of medial mobile-bearing unicompartmental knee arthroplasty (UKA) in different BMI groups. This study aimed to determine the effect of patient body mass index (BMI) on patient-reported outcomes and long-term survival of medial UKA in a large non-registry cohort. Our hypothesis is that increasing BMI would be associated with worse outcomes. METHODS:Data were analysed from a prospective cohort of 1000 consecutive medial mobile-bearing Oxford UKA with mean 10-year follow-up. Patients were grouped: BMI < 25, BMI 25 to < 30, BMI 30 to < 35 and BMI 35+. Oxford Knee Score (OKS) and Tegner Activity Score were assessed at 1, 5 and 10 years. Kaplan-Meier survivorship was calculated and compared between BMI groups. RESULTS:All groups had significant improvement in OKS and Tegner scores. BMI 35 + kg/m experienced the greatest overall increase in mean OKS of 17.3 points (p = 0.02). There was no significant difference in ten-year survival, which was, from lowest BMI group to highest 92%, 95%, 94% and 93%. CONCLUSION:There was no difference in implant survival between groups, and although there was no consistent trend in postoperative OKS, the BMI 35+ group benefited the most from UKA. Therefore, when UKA is used for appropriate indications, high BMI should not be considered to be a contraindication. Furthermore rationing based on BMI seems unjustified, particularly when the commonest threshold (BMI 35) is used. LEVEL OF EVIDENCE:III. 10.1007/s00167-018-5218-6
    No radiographic difference between patient-specific guiding and conventional Oxford UKA surgery. Kerens Bart,Schotanus Martijn G M,Boonen Bert,Kort Nanne P Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:Implant position is an important factor in unicompartmental knee arthroplasty (UKA) surgery. Results on conventional UKA alignment are commonly described in literature. Patient-specific guiding (PSG) is a new technique for positioning the Oxford UKA. Our hypothesis is that PSG improves component position without affecting the HKA angle. METHODS:This prospective study compares the results of our first thirty cases of cementless Oxford UKA using PSG with thirty cases using conventional outlining. Baseline characteristics for both groups were identical. Details on handling of the guide, estimated blood loss and operation time were recorded. Postoperative screened radiographs and standing long-leg radiographs of both groups were compared. RESULTS:Median AP position of the femoral component was 3 degrees varus (-5 to 9) using PSG versus 2 degrees varus (-10 to 8) for the conventional group. For the femoral flexion, this was 9 degrees flexion (0-16) using PSG versus 12 degrees flexion (0-20). The tibial median AP position was 1 degree varus (-3 to 7) using PSG versus 2 degrees varus (-5 to 10). The median tibial posterior slope was 5 degrees (1-10) using PSG versus 5 degrees (0-12). All guides aligned well. No conversion to conventional outlining was performed, and no significant changes had to be made to the original approved plan. Operation time, estimated blood loss and postoperative haemoglobin drop were not significantly different between both groups. DISCUSSION:Implant position was not different between both groups, even in the early phase of the learning curve. Perioperative results were not different between both groups. LEVEL OF EVIDENCE:III. 10.1007/s00167-014-2849-0
    The risk of revision after TKA is affected by previous HTO or UKA. Robertsson Otto,W-Dahl Annette Clinical orthopaedics and related research BACKGROUND:High tibial osteotomy (HTO) and unicompartmental arthroplasty (UKA) are reconstructive surgeries advocated for younger patients. In case of failure or progression of osteoarthritis, they can both be converted to a total knee arthroplasty (TKA). QUESTIONS/PURPOSES:We used registry data to answer if the risks of revision for TKAs after previous HTOs and UKAs differ and how these compare with that of de novo TKAs. Furthermore, we wanted to examine the extent of stemmed/revision implants being used for the conversions. METHODS:We identified HTOs performed during 1998 to 2007 with the help of the inpatient and outpatient care registries of the Swedish National Board of Health and Welfare and gathered relevant information from hospital records. The Swedish Knee Arthroplasty Register was then examined to find all de novo TKAs, TKAs performed after HTO, and TKAs performed after UKA through the end of 2012. RESULTS:For 920 TKAs after previous UKA and 356 TKAs after previous closed-wedge HTOs, we found the risk of revision significantly higher than for the 118,229 de novo TKAs (risk ratio, 2.8; confidence interval [CI], 2.2-3.5; p<0.001, and 1.7 CI, 1.1-2.6; p<0.001, respectively), whereas for the 482 open-wedge osteotomies, the difference was not significant (risk ratio, 1.2; CI, 0.8-1.8; p=0.44). Stemmed implants were used in 663 of the 117,566 primary de novo TKAs (0.6%), in 22 of the 809 HTO conversions (4%) and in 136 of the 920 UKA conversions (17%). CONCLUSIONS:TKAs after previous reconstructive surgery carry an increased risk for revision. However, our findings do not mitigate against the use of UKA and HTO in selected cases. LEVEL OF EVIDENCE:Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. 10.1007/s11999-014-3712-9
    Abnormal preoperative MRI does not correlate with failure of UKA. Hurst Jason M,Berend Keith R,Morris Michael J,Lombardi Adolph V The Journal of arthroplasty Modern indications for medial mobile-bearing unicompartmental knee arthroplasty (UKA) include a normal lateral compartment, minimal patellofemoral disease, and a ligamentously stable knee. Radiographs and intraoperative inspection can determine the appropriateness of UKA. Magnetic resonance imaging (MRI) interpretations can over-estimate the degree of knee pathology. This study reports the outcomes of UKA performed despite an abnormal MRI of the lateral compartment, patellofemoral compartment, and/or cruciate ligaments. One thousand consecutive medial UKAs were reviewed, and 33 patients had pre-operative MRI with interpretations of osteoarthritic changes in the lateral compartment, patellofemoral compartment, and/or deficiency of the anterior cruciate ligament (ACL). We compared the postoperative Knee Society pain score, total score, and functional score between the abnormal MRI group (n=33) and the remaining patients (n=967). Average follow-up was 43.4months and 38.3months for the two groups, respectively. Knee Society pain, total, and functional scores for the abnormal MRI group were 40.8, 88.7, and 78.5 respectively compared with 43.4, 90.6, and 80.0 respectively for the remaining patients. The failure rate was 3% (1/33) in the abnormal MRI group and 4% (39/967) in the remaining patients. Based on the numbers available, there were no differences between the two groups in terms of survival and clinical results. The results of this study suggest abnormal preoperative MRI findings do not have an influence on the outcome of UKA when modern radiographic and clinical criteria are met. 10.1016/j.arth.2013.05.011
    Clinical outcome after UKA and HTO in ACL deficiency: a systematic review. Mancuso Francesco,Hamilton Thomas W,Kumar Vijay,Murray David W,Pandit Hemant Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA PURPOSE:In the treatment of medial osteoarthritis secondary to anterior cruciate ligament (ACL) injury there is no consensus about optimum treatment, with both high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) being viable options. The aim of this review was to compare the outcomes of these treatments, both with or without ACL reconstruction. METHODS:EMBASE, MEDLINE and the Clinical Trials Registers were searched to identify relevant studies. Studies meeting pre-defined inclusion criteria were assessed independently by two researchers for methodological quality and data extracted. RESULTS:Twenty-six studies involving 771 patients were identified for inclusion. No randomized controlled trials were identified. Seventeen studies reported outcomes following HTO and nine studies reported outcomes following UKA. HTO patients were significantly younger than those receiving UKA, and ACL reconstruction patients were younger than non-reconstructed patients. Treatment with HTO ACL reconstruction had the lowest revision rate (0.62/100 observed component years) but the highest rate of complications (4.61/100 observed component years). Too little data were available to test for differences in outcome between different surgical techniques or prosthesis designs. CONCLUSIONS:Limited conclusions about the optimum treatment can be made due to the absence of controlled trials. In patients treated with HTO ACL reconstruction, the high complication rate likely outweighs its minimally superior survival. Outcomes following UKA ACL reconstruction are similar to outcomes for UKA in the ACL intact knee without any increase in complications. As such in patients meeting indications for UKA, UKA ACL reconstruction should be performed with further work required to identify the optimum treatment in other patient groups. LEVEL OF EVIDENCE:IV. 10.1007/s00167-014-3346-1
    Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis. Wilson Hannah A,Middleton Rob,Abram Simon G F,Smith Stephanie,Alvand Abtin,Jackson William F,Bottomley Nicholas,Hopewell Sally,Price Andrew J BMJ (Clinical research ed.) OBJECTIVE:To present a clear and comprehensive summary of the published data on unicompartmental knee replacement (UKA) or total knee replacement (TKA), comparing domains of outcome that have been shown to be important to patients and clinicians to allow informed decision making. DESIGN:Systematic review using data from randomised controlled trials, nationwide databases or joint registries, and large cohort studies. DATA SOURCES:Medline, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Clinical Trials.gov, searched between 1 January 1997 and 31 December 2018. ELIGIBILITY CRITERIA FOR SELECTING STUDIES:Studies published in the past 20 years, comparing outcomes of primary UKA with TKA in adult patients. Studies were excluded if they involved fewer than 50 participants, or if translation into English was not available. RESULTS:60 eligible studies were separated into three methodological groups: seven publications from six randomised controlled trials, 17 national joint registries and national database studies, and 36 cohort studies. Results for each domain of outcome varied depending on the level of data, and findings were not always significant. Analysis of the three groups of studies showed significantly shorter hospital stays after UKA than after TKA (-1.20 days (95% confidence interval -1.67 to -0.73), -1.43 (-1.53 to -1.33), and -1.73 (-2.30 to -1.16), respectively). There was no significant difference in pain, based on patient reported outcome measures (PROMs), but significantly better functional PROM scores for UKA than for TKA in both non-trial groups (mean difference -0.58 (-0.88 to -0.27) and -0.32 (-0.48 to -0.15), respectively). Regarding major complications, trials and cohort studies had non-significant results, but mortality after TKA was significantly higher in registry and large database studies (risk ratio 0.27 (0.16 to 0.45)), as were venous thromboembolic events (0.39 (0.27 to 0.57)) and major cardiac events (0.22 (0.06 to 0.86)). Early reoperation for any reason was higher after TKA than after UKA, but revision rates at five years remained higher for UKA in all three study groups (risk ratio 5.95 (1.29 to 27.59), 2.50 (1.77 to 3.54), and 3.13 (1.89 to 5.17), respectively). CONCLUSIONS:TKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis. By directly comparing the two treatments, this study demonstrates better results for UKA in several outcome domains. However, the risk of revision surgery was lower for TKA. This information should be available to patients as part of the shared decision making process in choosing treatment options. SYSTEMATIC REVIEW REGISTRATION:PROSPERO number CRD42018089972. 10.1136/bmj.l352