U.S. Department of Defense


Date of this Version



Clinical Biomechanics 29 (2014) 235–242


This article is a U.S. government work, and is not subject to copyright in the United States.


Background: Abnormal mechanics of locomotion following lower-extremity amputation are associated with increases in trunk motion,which in turn may alter loads at the lowback due to changes in inertial and gravitational demands on the spine and surrounding trunk musculature. Methods: Over-ground gait data were retrospectively compiled from two groups walking at similar self-selected speeds (~1.35 m/s): 40 males with unilateral lower-extremity amputation (20 transtibial, 20 transfemoral) and 20 able-bodied male controls. Three-dimensional joint reaction forces andmoments at the lowback (L5/S1 spinal level)were calculated using top-down and bottom-up approaches. Peak values and the timings of thesewere determined and compared between and within (bilaterally) groups, and secondarily between approaches. Findings: Peak laterally-directed joint reaction forces and lateral bend moments increased with increasing level of amputation, and were respectively 83% and 41% larger in prosthetic vs. intact stance among persons with transfemoral amputation. Peak anteriorly-directed reaction forces and extension moments were 31% and 55% larger, respectively, among persons with transtibial amputation compared to controls. Peak vertical reaction forces and axial twist moments were similar between andwithin groups. Peak joint reaction forces and moments were larger (3–14%), and the respective timing of these sooner (11–62 ms), from the bottom-up vs. top-down approach. Interpretation: Increased and asymmetric peak reaction forces and moments at the lowback among personswith unilateral lower-extremity amputation, particularly in the frontal plane, suggest potential mechanistic pathways through which repeated exposure to altered trunk motion and spinal loading may contribute to low-back injury risk among persons with lower-extremity amputation