The purpose of this study was to compare patient performance 6 months after total knee replacement with a matched group of healthy subjects. There were 20 subjects in each group. The subjects performed 3 well-documented functional performance tests; Timed Up and Go, Stair Climbing Test, and 6-Minute Walk Test. Biomechanical data was collected on a Step Up and Over Test. The subjects step up on a 20.5 cm step and then down the other side. Trials were performed with the operated limb stepping up and with the operated limb stepping down.