My Orthopaedic Surgeon Suggests a Unicompartmental Knee Replacement: a Detailed Look at the Long-term Outcomes of a Single Surgeon's Practice

Aim: This single surgeon case series with up to 29-year follow-up evaluated the survival of the Oxford unicompartmental knee replacement (UKR) for isolated medial compartment osteoarthritis.

Method: Four hundred and four knees in 330 patients were followed for between 12 days to 29 years, with an average of 13 years. Kaplan-Meier survival estimates were calculated using revision for total knee replacement and re-operation for any reason over 5-year intervals. Revision and reoperation rates per 100 component years were used to compare subsets, cemented and uncemented prostheses and Phase 2 and Phase 3 instrumentation.

Results: Of 404 UKRs, 292 (72%) were cemented, 96 (24%) uncemented and 16 hybrid (4%); 137 (34%) were undertaken using Phase 2 instrumentation and 267 (66%) Phase 3 instrumentation. Estimated revision-free implant survival at 20 years was 78%, and estimated reoperation-free survival at 20 years was 72%.

Conclusion: Unicompartmental knee replacement is a very successful procedure, with 78% of knees remaining revision-free at 20 years. Progression of lateral compartment arthritis was the most common cause for revision, affecting 60% of revision cases. There was no significant difference in the revision or reoperation rate between cemented and uncemented prostheses or Phase 2 and minimally invasive Phase 3 instrumentation.