• B Y Xu, B C Ji, W T Guo, W B Mu, and L Cao.
• Department of Orthopaedic Surgery, First Teaching Hospital of Xinjiang Medical University, Urumqi 830054, China.
• Zhonghua Wai Ke Za Zhi. 2017 Jun 1; 55 (6): 416-422.

AbstractObjective: To evaluate the influence of patellofemoral joint degeneration and pre-operative pain location on the outcome of medial Oxford unicompartmental knee arthroplasty (UKA). Methods: A total of 58 patients (58 knees) with medial Oxford UKA had been performed for medial osteoarthritis from March 2013 to July 2014 in Department of Orthopaedic Surgery at First Teaching Hospital of Xinjiang Medical University were retrospective reviewed. There were 24 males and 34 females, the age from 43 to 87 years with the mean age was 68.5 years. The mean body mass index was 25.2 kg/m(2) ranging from 19.7 to 31.5 kg/m(2). Patients were divided into anterior-medial pain group (35 knees), anterior knee pain group (17 knees) and general knee pain group (6 knees) according to pre-operative pain location. Pre-operative radiological statuses of the patellefemoral joint were defined by Ahlback system and divided into patellofemoral joint degeneration group (16 knees) and normal group (42 knees). Patients were also divided into medial patellofemoral degeneration group (20 knees), lateral patellofemoral degeneration group (12 knees) and normal group (26 knees) according to Altman scoring system. Outerbridge system was used intraoperatively and the patients were divided into patellofemoral joint degeneration group (21 knees) and normal group (37 knees). Pre- and post-operative outcomes were evaluated with Oxford Knee Score (OKS), Western Ontario and MacMaster (WOMAC) and patellofemoral score system of Lonner. T test and ANOVA were used to analyze the data. Results: The average duration of follow-up was 33 months (from 26 to 42 months). There were no patients had complications of infection, deep vein thrombosis, dislocation or loosing at the last follow-up. Compared to pre-operation, OKS (18.9±3.5 vs. 38.9±4.7, 19.3±4.2 vs. 39.6±4.6, 18.1±3.2 vs. 38.1±3.7)(t=5.64 to 7.08, all P<0.01) and WOMAC (10.9±2.3 vs.53.2±4.5, 10.4±2.1 vs.54.6±3.4, 11.7±1.8 vs.52.8±3.7)(t=14.50 to 19.16, all P<0.01) decreased, and the Lonner score (88.9±3.4 vs.38.6±2.8, 87.5±4.1 vs.38.2±2.3, 88.2±3.2 vs. 37.6±3.5)(t=-19.78 to -18.16, all P<0.01) increased significantly in anterior-medial pain group, anterior knee pain group and general knee pain group. According to Ahlback scoring system, compared to pre-operation, OKS (18.3±2.4 vs. 38.7±4.4, 19.6±1.8 vs. 38.4±3.1)(t=7.05, 9.08, both P<0.01) and WOMAC (10.6 ±2.6 vs.53.2±4.5, 12.1±1.4 vs.52.4±3.3)(t=14.21, 19.52, both P<0.01) decreased, the Lonner score (88.1±3.1 vs.38.3±3.3, 86.9±2.6 vs.39.1±2.4)(t=-18.90, -23.40, both P<0.01) increased significantly in patellofemoral joint degeneration group and normal group, the outcomes were the same according to Altman and Outerbridge scoring system. There was no significant difference between patellofemoral joint degeneration group and normal group based on Ahlback grading system. According to Altman classification, compared to normal group, there was no statistically differences in OKS, WOMAC and Lonner scoring system between patients with degeneration in the medial patellofemoral joint group, OKS and WOMAC increased (20.2±1.4 vs.18.2±2.7, 12.5±1.7 vs.10.5±2.5) (t=-4.30, P=0.03; t=-4.80, P=0.02), the Lonner score decreased (84.3±2.8 vs.87.4±3.2) (t=-6.20, P=0.01) in lateral patellofemoral degeneration group. According to Outerbridge scoring system, there were no statistically differences in patients in patellofemoral joint degeneration group and normal group. Conclusions: There is a good evidence that neither mild to moderate degree of patellofemoral joint degeneration nor pre-operative pain location will compromise the short-term outcome of medial Oxford UKA, and should not be considered as contraindications. The situation is less clear for lateral patellofemoral degeneration, and more cautious option is advised.

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