• Robert J Zmitrewicz, Richard R Neptune, Judith G Walden, William E Rogers, and Gordon W Bosker.
• Department of Mechanical Engineering, University of Texas, Austin, TX 78712, USA.
• Arch Phys Med Rehabil. 2006 Oct 1; 87 (10): 1334-9.

ObjectiveTo 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.DesignSubjects 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.SettingGait analysis laboratory.ParticipantsFifteen healthy unilateral transtibial amputees (>55 y) who had an amputation at least 1 year before testing because of vascular disorders.InterventionsNot applicable.Main Outcome MeasuresThe 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).ResultsAmputees 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.ConclusionsThese 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.

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