A major component of the joint-specific scoring systems is ROM [3 and 7]. This measure is widely used because it is an easily understood, direct measure of the joint's condition. Despite the intuitive connection between joint flexibility and operative success, it remains to be shown how ROM influences the most important outcome: a patient's ability to use the prosthetic joint in activities of daily living. Because ROM requires evaluation by a clinician, it cannot be collected in large studies conducted by mail or telephone