Mediolateral joint powers at the low back among persons with unilateral transfemoral amputation

Objective: To analyze mediolateral joint powers at the low back during gait among persons with and without unilateral transfemoral amputation to better understand the functional contributions of tissues in and around the low back to altered lateral trunk movements in this population.

Design: Retrospective analysis of biomechanical gait data.

Setting: Gait laboratory.

Participants: Twenty persons with unilateral transfemoral amputation and 20 uninjured controls (N=40).

Interventions: Not applicable.

Main outcome measures: Net joint powers, and total generation (+) and absorption (-) energies, at the low back (L5/S1 spinal level) were analyzed in the frontal plane using inverse dynamics analyses on over-ground gait data collected at self-selected walking speeds (∼1.3m/s).

Results: Compared with uninjured controls, 4 distinctly larger positive phases of mediolateral joint power at L5/S1 were evident in persons with transfemoral amputation, occurring before and after each heel strike. Total generation energies throughout the gait cycle were also larger (P<.001) among persons with transfemoral amputation (4.8±1.4J) than among uninjured controls (1.3±0.7J).

Conclusions: Larger positive phases of joint power at L5/S1 in the frontal plane support previous suggestions that persons with transfemoral amputation use a more active mediolateral trunk movement strategy, although such an active trunk movement strategy with transfemoral amputation may contribute to higher metabolic energy expenditures and low back pain risk.