Revision of the Unstable Total Knee Arthroplasty. Outcome Predictors

Revision arthroplasty is often required for confirmed cases of symptomatic tibiofemoral instability after total knee arthroplasty (TKA). We evaluated the results of revision for TKA instability in a consecutive series of 67 patients (68 knees) between 2000 and 2006. Outcome measures were surgeon-based assessment of knee stability, Knee Society Score, and Short Form Health Survey 36. At an average of 39 months of follow-up, the mean Knee Society Score and Short Form Health Survey 36 physical and mental scores were 76, 53, and 67 points, respectively. Knee instability persisted in 14 patients (22%). Data at the 95% confidence level revealed that revising both the femoral and tibial components, the use of femoral augments, and smaller joint line elevation as measured on radiographs correlated significantly with achieving a stable knee. In revision surgery for TKA instability, revision of both components and the use of femoral augments seem to offer the most predictable outcome.