The influence of alignment in long-term functional outcome of total knee arthroplasty.

Abstract

This study aimed to analyze long-term survival rate and clinical outcomes of a NexGen LPS knee system. The effect of component alignment parameters on clinical scores and patient satisfaction was also investigated. Between June 2002 and January 2010, 204 knees of 152 patients underwent total knee arthroplasty with NexGen LPS-Flex knee system with fix bearings. The mean follow-up was 13.2 (range, 10 to 18 years). The relationship between radiologic and clinical results was investigated with component angles. Outlier angles were determined according to cutoff values of alpha, beta, gamma, and delta angles on the radiographs taken immediately after the operation. Knees were classified based on existing outliers they have as "No Outliers" (Group 1), "Single Outliers" (Group 2), and "Multiple Outliers" (Group 3). Revision surgery was required for ten patients, and the overall survival rate was 95.1% at the last follow-up. "Single Outliers" did not show a clinically significant difference in functional scores compared to the "No Outliers" group. However, KSKS and FJS-12 were significantly lower in "Multiple Outliers" knees (p: 0.039 and 0.019, respectively). NexGen LPS-Flex knee system has satisfactory results with 95.1% implant survival in 13.2 years. FJS-12 measurements at the end of the follow-up demonstrate a favourable result of the fixed bearing design. On two plane X-ray evaluations, components malaligned with two or more outliers in the same knee deteriorate patient satisfaction and clinical results.