The influence of joint line restoration on the results of revision total knee arthroplasty: comparison between distance and ratio-methods

Abstract

Introduction: Restoring the joint line (JL) in primary as well as revision total knee arthroplasty (TKA) influences clinical results as well as long-term survival rates. Whereas studies agree about the negative effect of JL alteration, the reference system of choice is unclear. The purpose of the present study was to evaluate the effect of JL allocation comparing a ratio to a distance method on clinical outcome following revision TKA.

Materials: After a miminum follow-up of 2 years JL reconstruction was evaluated in 69 consecutive patients after revision TKA. Clinical results were obtained using the Knee Society Score (KSS). We used the Figgie distance method in comparison to the epicondylar ratio method.

Results: The mean postoperative KSS significantly improved in all 69 revision TKAs compared to the preoperative value. Patients with a positive JL reconstruction in reference to the epicondylar ratio showed significantly better KSS results compared to knees without restoration of the JL. The degree of JL reconstruction depending on the distance method showed no effect on postoperative KSS results.

Conclusion: We recommend the epicondylar ratio to calculate the physiological JL rather than JL allocation by a distance.