[The influence of patellofemoral joint degeneration on outcome of Oxford medial unicompartmental knee arthroplasty]

Abstract

Objective: To explore the influence of lateral patellofemoral joint degeneration on the treatment of anteromedial osteoarthritis of knee joint by Oxford medial unicompartmental knee arthroplasty. Methods: The clinical data of 73 patients (73 knees) with knee osteoarthritis underwent unicompartmental knee arthroplasty at Department of Orthopaedic Surgery, Xuanwu Hospital, Capital Medical University from March 2016 to December 2017 were analysed respectively.There were 18 males and 55 females, aged (68.6±7.5) years(range: 53 to 89 years).The lateral patellofemoral joints of patients were evaluated by Ahlback grading system. Patients with Ahlback 0 andⅠ were in the non degenerative group (37 cases), and those with Ahlback Ⅱ and above were in the degenerative group (36 cases). Hospital for special surgery knee score(HSS) and the Western Ontario and McMaster Universities(WOMAC) osteoarthritis index, as well as the condition of kneeling, sit to stand movement, up stair and down stair were recorded. The data before and after operation were compared by paired sample t test, and the data between groups were compared by independent sample t test. χ(2) test was used for counting data. Pearson correlation analysis was used to compare the correlation between ahlback score, HSS and WOMAC osteoarthritis index. Results: The follow-up time was (35.1±6.6) months (range: 25 to 47 months).The knee function of the patients improved significantly after operation.The HSS score increased from 57.7±11.8 preoperative to 81.8±7.8 postoperative (t=16.64, P=0.00) and WOMAC osteoarthritis index decreased from 48.9±13.4 preoperative to 15.6±8.8 postoperative (t=20.48, P=0.00). There was no statistical difference in the change of HSS between the degenerative group and the non-degenerative group before and after surgery(27.5±12.2 vs. 22.5±12.3, t=-1.65, P=0.10) as well as the change of WOMAC osteoarthritis index(31.8±14.0 vs. 36.4±13.7, t=-1.35, P=0.18), but the lateral patellofemoral joint degeneration was related to inability to complete squats (χ(2)=5.17, P=0.04) and sitting up (χ(2)=7.22, P=0.01). Conclusion: The degeneration of lateral patellofemoral joint has no effect on the early functional recovery of patients with anteromedial knee osteoarthritis after Oxford medial unicompartmental knee arthroplasty.

Keywords: Degeneration; Osteoarthritis, knee; Patellofemoral joint; Treatment outcome; Unicompartmental knee arthroplasty.