The effect of prosthetic ankle mobility in the sagittal plane on the gait of transfemoral amputees wearing a stance phase controlled knee prosthesis

An experimental method was developed to determine the effects of prosthetic ankle mobility in the sagittal plane on the gaits of transfemoral amputees wearing a stance and swing (SNS) phase controlled knee prosthesis. Specially designed ankles with different ranges of motion in the sagittal plane were applied to rigid foot prostheses in order to exclude possible foot-ankle system interactions. The developed method was examined on even ground with five male transfemoral amputees wearing a SNS knee. The relative knee flexion-extension angles (defined as differences between maximum and minimum knee flexion angles) between initial contact and opposite initial contact were used to obtain changes in impact energy absorption in SNS knees in the early stance phase for two different ranges of ankle motion in the sagittal plane. Notable changes in relative knee flexion-extension angles were observed for the no-motion ankles, but no change in relative knee flexion-extension angles was observed for the maximum-motion ankles. Therefore, it is possible that sagittal mobility of a foot-ankle system is an important factor for inducing early flexion-extension movement of the knee in the stance phase of gait of transfemoral amputees wearing a SNS knee.