Does activity affect the outcome of the Oxford unicompartmental knee replacement?
Ali AM., Pandit H., Liddle AD., Jenkins C., Mellon S., Dodd CA., Murray DW.
High levels of activity are considered to be a contraindication to unicompartmental knee replacement (UKR) and are not recommended after UKR. To determine if these recommendations should apply to the mobile-bearing Oxford UKR, this study assessed the effect of post-operative activity level on the outcome of this device.The outcome of the first 1000 Phase 3 cemented Oxford UKRs implanted between 1998 and 2010 was assessed using survival analysis, the Oxford Knee Score (OKS) and the American Knee Society Objective (KSS-O) and Functional (KSS-F) Scores. Patients were grouped according to the maximum post-operative Tegner Activity Score.The mean follow-up was 6.1 years (range 1 to 14). Overall, increasing activity was associated with superior survival (p=0.025). In the high activity group, with Tegner≥5 (n=115) 2.6% were revised and the 12-year survival was 97.3% (confidence interval (CI): 92.0% to 99.1%). In the low activity group, with Tegner≤4, (n=885) 4.3% were revised and the 12-year survival was 94.0% (CI: 91.4 to 95.8). The difference between the two groups was not significant (p=0.44). Although the final OKS and KSS-F were significantly better in the high activity group compared to the low activity group (OKS 45v40, KSS-F 95v78), there was no difference in the change in OKS or KSS-O.High activity does not compromise the outcome of the Oxford UKR and may improve it. Activity should not be restricted nor considered to be a contraindication.