A method for location of prosthetic and orthotic knee joints.

2 Chief, Orthopedic Surgery, Duke University Medical Center, Durham, N. C; Chief, Orthopedic and Prosthetic Appliance Clinic Team, Veterans Administration Hospital, Durham, N. C. When it is necessary to use a mechanical knee joint, whether it be in a below-knee prosthesis or a long-leg brace, ideally there should be no relative motion between the patient's limb and the appliance during its use. Because the human knee is not a single-axis joint, analogues of the human knee employing more than one axis of rotation have been developed but none have proven practical, owing largely to bulkiness, but to some degree to cost. At this time, therefore, we are faced with the problem of determining a method of placing the center of rotation of a single-axis mechanical knee joint with respect to the knee so that the least amount of relative motion will occur between the patient and the appliance. This article describes a method of determining the optimum location of single-axis knee joints, based on data accumulated recently from X-rays and from cadaver dissection.