Compensatory mechanisms in below-knee amputee gait in response to increasing steady-state walking speeds




Silverman, Anne Katherine

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Below-knee amputations result in the loss of the ankle plantar flexors, which have been shown to be the primary contributors to forward propulsion in late stance in nonamputee walking. Thus, significant compensatory mechanisms are expected to emerge, especially at higher walking speeds when the demand for forward propulsion is greater. The objective of this study was to examine amputee ground reaction force impulses and joint kinetics to identify compensatory mechanisms across a wide range of steady-state walking speeds. We hypothesized that amputees would rely more on their intact leg and generate greater intact leg propulsion relative to the residual leg as walking speed increased, which would result in greater ground reaction force asymmetry between legs. Amputee and control subject kinematic and kinetic data were collected for over-ground walking at four different speeds (0.6 m/s, 0.9 m/s, 1.2 m/s, and 1.5 m/s). Group average results showed no significant trend in the ratio between the residual and intact leg impulses, indicating that subjects maintained their level of braking and propulsion symmetry with the changing task demands of walking faster. Thus, our hypothesis was not supported. The primary compensatory mechanism was greater positive residual leg hip joint power and work in late stance, which may lead to greater propulsion from the residual leg. Therefore, rehabilitation strategies that strengthen the residual hip flexors may be useful in reducing asymmetry between the intact and residual legs.


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