77 patients with osteoarthritis of the knee were randomized to receive a total knee replacement with either a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) or a high-flexion rotating-platform posterior-stabilized design (RP-F). Throughout the course of the study, active non-weight-bearing flexion along with functional range of motion were measured to determine which total knee replacement design better allows patients to participate in daily activities. By the end of the 1 year study, it was determined that the RP-F group achieved greater active non-weight-bearing knee flexion, but reported more pain after surgery and had a lower weight bearing flexion during slope and level walking.