Twenty stiff (range of motion, less than 50 degrees) and six ankylosed knees were replaced with the posterior stabilized condylar prosthesis and evaluated after an average of 4.5 years (range, 2.5-7.5 years). There were 81% good to excellent, 11.5% fair, and 7.5% poor results. The maximum overall degree of flexion improved from an average of 60 degrees before surgery to 85 degrees after surgery. Flexion contracture was reduced from 28 degrees to 7 degrees, and the total arc of motion significantly increased from 32 degrees to 78 degrees. Less motion was achieved in the ankylosed knees. A modified inverted V-Y quadricepsplasty was a useful approach to the knee in 11 cases.