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.
Keywords: China; Functional outcome; Survivorship; Unicompartmental knee arthroplasty (UKA).