Ultrasound study of the motion of the residual femur within a trans-femoral socket during gait

This study analyses the motion of the residual femur within a trans-femoral socket during gait using ultrasound data from two simultaneously transmitt ing transducers connected to two ultrasound scanners. Calibration tests acc urately established the orientation of the two transducers mounted on the l ateral wall of the socket. Relative positions of the ultrasound image of th e femur were measured on video playback. Motion of the residual femur, rela tive to the lateral wall of the socket, at any instant during gait may be e stimated, if the relative positions of the two transducers and the motion o f the ultrasound image are known. A consistent pattern of femoral motion du ring 10 gait cycles is displayed graphically. The femoral motion in this pa per is expressed as abduction/adduction or flexion/extension relative to th e socket. However, without a full gait analysis study, the orientation of t he socket relative to the ground or relative to the pelvis cannot be determ ined. Only one ultrasound scanner may be available for clinical use. Hence data c ollection may be restricted to only one transducer during gait. In order to simulate the single transducer mode, the ultrasound data recorded during t he 10 previous gait cycles, was averaged at any instant of the gait cycle. The angular orientation of the femur was calculated based on the averaged d ata. Similar patterns of femoral motion were obtained irrespective of the t echnique adopted.