The Oxford unicompartmental knee prosthesis for the treatment of medial compartment knee disease: 2 to 5 year follow-up

Abstract

Background: Unicompartmental knee replacement has become a surgical alternative for treating isolated medial or lateral osteoarthritis of the knee or avascular necrosis of the femoral condyls.

Objectives: To evaluate the short-term results of the Oxford Phase 3 unicompartmental knee replacement for unicompartmental knee arthrosis or avascular necrosis of the medial femoral condyle.

Methods: During the period 2003-2005 a total of 59 patients (59 knees) underwent medial Oxford Phase 3 unicompartmental knee replacement in our unit. The patients were interviewed and examined, and standing anteroposterior and lateral X-rays were taken. All patients completed the Western Ontario and McMaster Universities Index of Osteoarthritis and the Short Form 12 questionnaire, and the International Knee Society score was evaluated. The data were collected and statistical analysis was performed.

Results: X-rays were performed and scores for the WOMAC and IKS were assessed for 42 patients (31 females, 11 males). At an average of 32 months after surgery the total WOMAC score was 30. The mean SF-12 physical score was 38 and the mean SF-12 mental score was 51. The mean IKS score was 166. Ninety-one percent of the patients had active flexion of 120 degrees or more. Of 59 knees 7 were converted to total knee arthroplasty--all of them within the first 2 years of starting the procedure and all of them in relatively young patients.

Conclusions: Despite the higher revision rate to TKR in this study, our findings confirm the short-term results reported in other studies of the Oxford medial unicompartmental knee and our early failure rate could be explained by a performance learning curve. This study confirms that this bone-preserving procedure should be considered in end-stage isolated unicompartmental osteoarthritis or avascular necrosis by surgeons who have the adequate training and experience.