SUMMARY A prospective, randomized, single-blinded clinical trial is proposed to compare three tibial tray designs for patients undergoing total knee arthroplasty. This study is designed to address the clinically important issues of tibial component modularity and fixation in total knee replacement.

The Zimmer NexGen Legacy knee system is an FDA approved device and in this study will be used with 1) a modular tibial tray inserted with cement and 2) a non-modular tibial tray inserted with cement, and 3) a non-modular tibial tray inserted without cement. The insertion of total knee components without cement has been done clinically for over 20 years but has not been specifically approved by the FDA. Thus treatment arm 3, a non-modular tray inserted without cement, would involve the so-called off-label use of the device. 136 cases will be assigned to each arm of the study. Each patient will be assessed two months after surgery, one year after surgery, two years after surgery, five years after surgery, and every three to five years thereafter. The principal outcome measures will be the Knee Society Clinical rating scale, the SF-36 and the presence of significant lucent lines.. These measures will be compared among patients in the 3 trial arms at 5 years post surgery (or at the last follow-up point for those who drop out or become lost to follow-up). The Knee Society scores and SF-36 scores will be analyzed using analysis of variance models Rates of significant lucencies, perioperative mortality, as well as complications such as deep vein thrombosis, pulmonary embolus, neurovascular complication, and infection will be compared among the groups using chi-square tests . Rates of revision surgery will be compared among the groups using survivorship methods.

PURPOSE The primary aim of the study is to compare the results obtained with each of three tibial designs for patients undergoing total knee arthroplasty. Those results will be measured with disease-specific (Knee Society Scores), global (SF-36), and outcome measures. Radiographic results consisting of standing alignment, lateral and skyline views of the surgical knee will be recorded and analyzed. Completion of the intial investigation will occur at the 5-year interval after the last enrolled patient.