The effect of foot and ankle prosthetic components on braking and propulsive impulses during transtibial amputee gait

Objective: To assess the influence of energy storage and return (ESAR) prosthetic feet and multi-axis ankles on ground reaction forces and loading asymmetry between lower limbs in transtibial amputees. Design: Subjects wore 2 different prosthetic feet with and without a multi-axis ankle and were analyzed using a blind repeated-measures multivariate analysis-of-variance design. Setting: Gait analysis laboratory. Participants: Fifteen healthy unilateral transtibial amputees (>55 y) who had an amputation at least 1 year before testing because of vascular disorders. Interventions: Not applicable. Main Outcome Measures: The anteroposterior ground reaction force impulse, peak ground reaction forces, and braking and propulsion impulse duration were analyzed as subjects walked at a self-selected speed while wearing each of the 4 foot-ankle prosthesis combinations. Statistical analyses were used to determine if there was a significant foot, ankle, or foot-ankle interaction effect on the outcome measures for each foot (P<.05). Results: Amputees generated a significantly greater propulsive impulse with the residual leg when wearing a multi-axis ankle with the ESAR and non-ESAR foot, which improved the propulsive symmetry between the residual and intact legs. There was no prosthetic foot effect on these measures. There were no significant differences in the peak residual-leg braking or propulsive ground reaction forces or the impulse durations due to the prosthetic foot, ankle, or foot-ankle interactions, although an increase in the propulsive impulse duration approached significance (P=.062) with a multi-axis ankle. Conclusions: These results suggest that amputee gait may improve with the prescription of multi-axis ankles that allow for greater propulsive impulses by the residual leg, which improve the loading symmetry between legs.