Roentgenological Study of Certain Stump—Socket Relationships in Above-knee Amputees with Special Regard to Tissue Proportions, Socket Fit and Attachment Stability

Abstract

Twenty-five healthy active male above-knee amputees were studied. They had been uniformly fitted with their prosthesis, which in all cases had a total-contact suction socket of laminated plastic, and their walking capacity with the prosthesis was good. Sixteen of the patients were studied with respect to tissue proportions in the stump and intact thigh, while all 25 underwent studies concerning socket fit and relative movement between femoral stump and socket.

Mean total cross-sectional area of amputation stump 5–10 cm above end of femur was calculated to be 63% of that of intact thigh. Mean cross-sectional area of skin and subcutaneous tissue of the stump exceeded that of intact thigh by 12% (0.01 > P > 0.001). Muscle and bone tissues of stump were 55% (P < 0.001) and 27% (0.01 > P > 0.001) less, respectively, than those of intact thigh. In the stump, skin and subcutaneous tissue were calculated to occupy a mean of 41.8%, muscle 53.9% and bone 4.3% of the total cross-sectional area. Corresponding tissue proportions in intact thigh were 21.3%, 75.0% and 3.7%.

In only about 40% of the patients was contact between stump and socket actually total. In the remainder there was a free space of varying size at the distal end between stump skin and socket

The femoral stump showed appreciable movement in the soft tissues within the socket. An arc of considerable dimension at the level of the knee and of the sole of the foot corresponded to observed changes in angulation of the femoral stump within the socket On full weight-bearing on the prosthesis alone the distal end of the femur assumed its most distal, lateral and posterior position, obviously as a result of active muscular function for achievement of lateral stabilization of the pelvis and prevention of flexion (collapse) of the prosthetic knee joint.