Ultrasound study of the motion of the residual femur within a trans-femoral socket during daily living activities other than gait.

Abstract

This study analyses the residual femur motion of a single amputee within a transfemoral socket during a series of daily living activities. Two simultaneously transmitting, socket mounted transducers were connected to two ultrasound scanners. Displacement measurements of the ultrasound image of the femur were video recorded and measured on "paused" playback. Abduction/adduction and flexion/extension of the residual femur within the socket at any instant during these activities were estimated, knowing the relative positions of the two transducers and the position of the residual femur on the ultrasound image. Consistent motion patterns of the residual femur within the trans-femoral socket were noted throughout each monitored daily living activity of the single amputee studied. Convery and Murray (2000) reported that during level walking, relative to the socket, the residual femur extends 6 degrees and abducts 9 degrees by mid-stance while flexing 6 degrees and adducting 2 degrees by toe-off. Uphill/downhill, turning to the right and stepping up/down altered this reported pattern of femoral motion by approximately 1 degree. During the standing activity from a seated position the femur initially flexed 4 degrees before moving to 7 degrees extension, while simultaneously adducting 6 degrees. During the sitting activity from a standing position the femur moved from 7 degrees extension and 6 degrees adduction to 3 degrees flexion and 1 degree abduction. The activity of single prosthetic support to double support introduced only minor femoral motion whereas during the activity of prosthetic suspension the femur flexed 8 degrees while simultaneously adducting 9 degrees. Additional studies of more amputees are required to validate the motion patterns presented in this investigation.