Functional Outcomes in People with Transtibial Amputation Using Crossover and Energy-Storing Prosthetic Feet: A Pilot Study

Abstract

ABSTRACT Introduction Contemporary prosthetic feet are purposefully designed to address the many functional limitations experienced by people with transtibial amputation (TTA). Choice of materials, geometry, and fabrication techniques contribute to the overall performance of the foot, and ultimately to the functional outcomes achieved by the user. The crossover foot is a novel foot design that integrates features from traditional energy-storing feet and modern, running-specific feet in an effort to maximize performance and energy return. Although initial user feedback is promising, research is needed to determine whether the crossover foot is capable of improving user outcomes relative to other types of contemporary prosthetic feet. Materials and Methods A cross-sectional pilot study was conducted to evaluate mobility, endurance, perceived exertion, and walking performance attained by participants wearing prostheses with crossover and energy-storing feet. Participants with unilateral TTA were administered a short battery of performance-based tests while wearing a prosthesis with a crossover foot and a prosthesis with a traditional energy-storing foot. The order of prostheses worn was randomly assigned. Tests included the Timed Up and Go (TUG) performed at comfortable speed, the TUG performed at fast speed, and the 6-minute walk test (6MWT). Spatiotemporal measures (speed, cadence, step length, step width, and step time) were assessed during the 6MWT using a GAITRite electronic walkway. Participants were asked to report their perceived exertion following the 6MWT using the Borg rating of perceived exertion (CR100). Results Seven participants completed all pilot study procedures. On average, participants exhibited better mobility at comfortable and fast speeds (0.83 second and 0.63 second faster during the TUG-comfortable and TUG-fast, respectively), improved endurance (19.7 m farther in the 6MWT), reduced perceived exertion (12.9 points less on the Borg CR100), increased speed (0.05 m/s), faster cadence (2 steps/min), and longer sound side steps (3.3 cm) while wearing the crossover foot than when wearing the energy-storing foot. However, not all participants exhibited the same functional benefits from using the crossover foot. Conclusions The crossover foot is a promising prosthetic foot design that appears to provide modest functional benefits to transtibial prosthesis users. Given the pilot nature of this study, additional research is needed to assess benefits across a larger and more diverse range of users to inform prescription practices.