The influence of the posterior cruciate ligament and component design on joint line position after primary total knee arthroplasty.

This study investigated the change in joint line position after posterior cruciate-retaining and posterior-stabilized total knee arthroplasty with AMK (DePuy, Warsaw, Ind) and Genesis II (Smith & Nephew, Memphis, Tenn) components. A total of 200 primary total knee arthroplasty patients were randomly selected so as to have 50 patients with each of the 4 prosthesis types. Joint line position was measured on preoperative and 2 year postoperative radiographs by both a lateral and an anteroposterior measurement method. Two-year follow-up functional data were assessed. There were no statistically significant differences in the joint line elevation between posterior-stabilized and posterior cruciate-retaining designs within the same implant system as measured on lateral radiographs. There were no differences in clinical functional outcomes in patients with variable joint line elevation.