The Oxford Medial Unicompartmental Knee Arthroplasty: The South African Experience

Background; The Oxford unicompartmental knee arthroplasty (OUKA) is a successful treatment for endstage, symptomatic anteromedial osteoarthritis. This study reports the results of a cohort of consecutive cemented and cementless medial OUKAs from an independent center and aims to answer the following questions: what is the survival of OUKA in the hands of a nondesigner surgeon? Are there any differences in the survival of cementless and cemented OUKA? Are the failure modes any different with the cementless and cemented OUKA?

Methods; One thousand one hundred twenty consecutive OUKAs were implanted in a single center for the recommended indications. Patients were prospectively identified and followed up. Survival was calculated with revision as the end point.

Results; There were 522 cemented and 598 cementless implants. The mean follow-up was 8.3 years for cemented implants (range 0.5-17, standard deviation [SD] 2.9) and 2.7 years (range 0.5-7, SD 1.8) for cementless implants. The Oxford knee score improved from a preoperative mean of 22 (SD 8.1) to 40 (SD 7.9) at the last follow-up (P < .001). There were 59 failures requiring revision surgery, with a 5.3% cumulative revision rate. The most common reason for failure was progression of osteoarthritis in the lateral compartment, occurred in 26 cases (2.3%). The cumulative 10-year survival was 91% (95% confidence interval 87.3-95.2).

Conclusion; The results of this prospective, consecutive case series from the African continent demonstrated that excellent results are achievable with the OUKA in independent centers if the correct indications and surgical technique are used.