Residual femur motion during the stance phase of gait is associated with dynamic stability in individuals with transfemoral amputations.

Abstract

Individuals with lower-limb amputations are at an increased risk of falling due to instability during functional tasks, such as gait. It has been postulated that a well fitted socket will reduce residual femur motion, thereby improving mobility for individuals with transfemoral amputations. However, the relationship between residual femur motion and dynamic stability has not been rigorously tested. Dynamic biplane radiography and a validated volumetric registration process were used to measure residual femur motion relative to 3 to 7 different sockets in 8 individuals with transfemoral amputations during treadmill walking. Correlations between residual femur range of motion during the stance phase of gait and dynamic stability metrics across participants, including bilateral minimum mediolateral margin of stability and mediolateral margin of stability asymmetry, and spatiotemporal variables were evaluated with Spearman's rank correlations (p < 0.05). Within-participant changes in residual femur range of motion and stability and spatiotemporal metrics were evaluated using repeated measures correlations (p < 0.05). Greater pistoning range of motion was correlated with greater prosthetic limb mediolateral margin of stability, mediolateral margin of stability asymmetry, and stance time asymmetry across participants. However, within-participant changes in residual femur pistoning range of motion due to altered socket design were not associated with within-participant changes in dynamic stability or spatiotemporal characteristics. Greater residual femur pistoning may be associated with poorer performance on dynamic stability metrics across individuals; however, a reduction in residual femur motion within an individual may not improve dynamic stability or reduce fall risk in individuals with transfemoral amputations. Clinical Trials ID: NCT05041998.