Outcomes of a Fixed-Bearing, Medial, Cemented Unicondylar Knee Arthroplasty Design: Survival Analysis and Functional Score of 460 Cases.

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty in isolated medial osteoarthritis (OA). However, despite satisfactory reports on the clinical performance, UKA revision rates are still concerning. This retrospective study reports on the long-term survivorship, functional outcomes, and reasons for revision in fixed-bearing UKA implant.

METHODS

Between 2005 and 2013, 460 consecutive patients were treated with medial UKA in one center using a fixed-bearing UKA system. All patients were evaluated clinically and radiographically before surgery, and postoperatively at 6 weeks and 1 year. Between February and April 2016, all patients were reevaluated using the Oxford Knee Score.

RESULTS

Mean follow-up was 5.5 (range, 2-11) years. The mean Oxford Knee Score was 43.3 (7-48), with 94.6% patients showing excellent or good outcomes. Eleven revisions (2.4%) occurred. The survivorship was 97.2% (95% confidence interval, 96.2%-99.2%) and 94.2% (95% confidence interval, 86.8%-97.5%) at 5 and 10 years, respectively, with revision of any implant component for any reason as the end point. The causes for revision were infection (4 cases, 0.9%); lateral pain due to overload (2 cases, 0.4%); progression of OA in the lateral compartment (2 cases, 0.4%); patellar pain with patellar chondropathy (2 cases, 0.4%); and severe synovitis (1 cases, 0.2%). There were no reoperations or revisions for component loosening, instability, component wear, or periprosthetic fracture.

CONCLUSION

A fixed-bearing UKA system is a good treatment option for medial end-stage OA. Satisfactory functional results were achieved with low incidence of complications and revisions.