A study to determine the effect of commercial prosthetic foot stiffness category on foot-ankle biomechanics, gait symmetry, community ambulation, and relative foot stiffness perception found that, after community use, the users’ perceptions of the relative stiffness of the feet were generally inconsistent.
Seventeen men with transtibial amputations participated and were fitted in randomized order with three consecutive stiffness categories of commonly prescribed prosthetic feet. Prosthetic foot roll-over shape and ankle push-off power and work were determined by 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.
The findings indicated that prosthetic foot roll-over radius increased with increased prosthetic foot stiffness categories, and. prosthetic ankle push-off peak power and work decreased with increased foot stiffness categories. 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.
The study’s authors found that 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. After community use, the participants’ perceptions of relative stiffness across feet were generally inconsistent with the order of prosthetic foot stiffness categories. The 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, the authors concluded.
The study, The effect of prosthetic foot stiffness on foot-ankle biomechanics and relative foot stiffness perception in people with transtibial amputation, was published in Clinical Biomechanics.