 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. 