Evaluation of 145 consecutive total knee arthroplasties pre- and postoperatively revealed that regardless of the preoperative deformity (varus, valgus, and flexion contracture), normal alignment of the knee with full extension was obtainable. The amount of flexion to be achieved postoperatively may be determined by the amount of flexion the patient had preoperatively, especially if the degree of flexion was less than 75 degrees. The prosthesis design, sex, age and diagnosis of rheumatoid arthritis were found not to correlate with postoperative motion and stability. In the osteoarthric knee, however, statistical analyses at 6 and 12 months generally showed less postoperative than preoperative range of motion.