Highlights
- •Prosthetic feet are available in different stiffnesses
- •There is limited evidence to guide stiffness selection during foot prescription
- •Prosthetic foot stiffness is associated with foot-ankle biomechanics changes
- •Perception of prosthetic foot stiffness was not consistent with stiffness category order
Abstract
Background
Prosthetic feet are available in a range of stiffness categories, however, there is
limited evidence to guide optimal selection during prosthetic foot prescription. The
aim of this study was to determine the effect of commercial prosthetic foot stiffness
category on foot-ankle biomechanics, gait symmetry, community ambulation, and relative
foot stiffness perception.
Methods
Participants were fit in randomized order with three consecutive stiffness categories
of a commonly-prescribed prosthetic foot. Prosthetic foot roll-over shape and ankle
push-off power and work were determined via data collected during walking in a motion
analysis laboratory. Step activity was recorded during community use of each foot.
Self-reported perception of relative foot stiffness was assessed with an ad hoc survey.
Findings
Seventeen males with transtibial amputation completed the study. Prosthetic foot roll-over
radius increased with increased prosthetic foot stiffness categories (p < 0.001). Both prosthetic ankle push-off peak power and work decreased with increased
foot stiffness categories (p = 0.002). There was no association between prosthetic foot stiffness category and
step length symmetry or steps per day. When assessed post-accommodation, there was
no association between relative foot stiffness perception and the stiffness category
across prosthetic foot conditions.
Interpretation
Prosthetic foot stiffness category was significantly associated with changes in prosthetic
foot-ankle biomechanical variables, however, was not associated with changes in gait
symmetry or community ambulation. Relative prosthetic foot stiffness perception after
accommodation was generally inconsistent with the order of prosthetic foot stiffness
categories.
Clinical relevance
While there were quantifiable differences in prosthetic foot-ankle biomechanics across
stiffness categories, no significant differences were detected in gait symmetry or
mean daily step count in the community. Furthermore, after community use, participants perceptions of relative stiffness
across feet were generally inconsistent with the order of prosthetic foot stiffness
categories. These findings raise questions as to whether changes in commercial prosthetic
foot stiffness category (within a clinically relevant range) affect subjective and
objective measures relevant to successful outcomes from prosthetic foot prescription.
Keywords
Abbreviations:
TTA (transtibial amputation), ESR (energy-storage and return), VAPSHCS (VA Puget Sound Health Care System), GRF (ground reaction force), CI (confidence interval), RR&D (Rehabilitation Research & Development), IRB (institutional review board)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: July 31, 2020
Accepted:
July 29,
2020
Received:
January 31,
2020
Identification
Copyright
Published by Elsevier Ltd.
