Transfemoral amputee recovery strategies following trips to their sound and prosthesis sides throughout swing phase

Abstract

BackgroundRecovering from trips is challenging for transfemoral amputees, and attempts often result in falls. Better understanding of the effects of the sensory-motor deficits brought by amputation and the functional limitations of prosthetic devices could help guide therapy and fall prevention mechanisms in prostheses. However, how transfemoral amputees attempt to recover from trips on the sound and prosthesis sides throughout swing phase is poorly understood.MethodsWe tripped eight able-bodied subjects and eight unilateral transfemoral amputees wearing their prescribed prostheses. The protocol consisted of six repetitions of 6 and 4 points throughout swing phase, respectively. We compared recovery strategies in able-bodied, sound side and prosthesis side limbs. The number of kinematic recovery strategies used, when they were used throughout swing phase, and kinematic characteristics (tripped limb joint angles, bilateral trochanter height and time from foot arrest to foot strike) of each strategy were compared across limb groups. Non-parametric statistical tests with corrections for post-hoc tests were used.ResultsAmputees used the same recovery strategies as able-bodied subjects on both sound and prosthesis sides, although not all subjects used all strategies. Compared to able-bodied subjects, amputees used delayed-lowering strategies less often from 30-60 % of swing phase on the sound side, and from 45-60 % of swing phase on the prosthesis side. Within-strategy kinematic differences occurred across limbs; however, these differences were not consistent across all strategies. Amputee-specific recovery strategies—that are not used by control subjects—occurred following trips on both the sound and prosthesis sides in mid- to late swing.ConclusionsCollectively, these results suggest that sensory input from the distal tripped leg is not necessary to trigger able-bodied trip recovery strategies. In addition, the differences between sound and prosthesis side recoveries indicate that the ability of the support leg might be more critical than that of the tripped leg when determining the response to a trip. The outcomes of this study have implications for prosthesis control, suggesting that providing correct and intuitive real-time selection of typical able-bodied recovery strategies by a prosthetic device when it is the tripped and the support limb could better enable balance recovery and avoid falls.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-015-0067-8) contains supplementary material, which is available to authorized users.

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“…Shirota et al 164 perturbed the swing phase of both individuals with a transfemoral amputation or knee disarticulation and without an amputation. They found that both groups use similar strategies although specific strategies are used more often in one group when compared to the other.…”

“…They found that both groups use similar strategies although specific strategies are used more often in one group when compared to the other. 164 This study was confounded by a number of factors. First of all we had a limited sample size, which affected the statistical power of the study.…”

“…164 In addition, they found the biggest differences between individuals with and without an amputation during tripping of the intact leg. 164 Sheehan et al 165 and Crenshaw et al 166 investigated the effect of a perturbation-based gait training program and found that this could improve compensatory stepping response and margins of stability. As far as it is known, no attempts have been made to investigate the effect of different prosthetic components on the responses to balance perturbations during walking.…”

“…Shirota et al studied the responses of individuals with a transfemoral amputation and control subjects on swing phase perturbations of both the prosthetic and intact leg. 164 They found that individuals with a transfemoral amputation generally used recovery strategies also used by individuals without an amputation. 164 In addition, they found the biggest differences between individuals with and without an amputation during tripping of the intact leg.…”

“…164 They found that individuals with a transfemoral amputation generally used recovery strategies also used by individuals without an amputation. 164 In addition, they found the biggest differences between individuals with and without an amputation during tripping of the intact leg. 164 Sheehan et al 165 and Crenshaw et al 166 investigated the effect of a perturbation-based gait training program and found that this could improve compensatory stepping response and margins of stability.…”