Evolution of an Adaptable Prosthetic Foot Design for Normalization of Biomechanics During Community Participation

Evolution of an Adaptable Prosthetic Foot Design for Normalization ofBiomechanics During Community Participation
Summary/AbstractThe vision of this project is to improve the functional physical mobility of people with lower extremity
amputations especially on uneven ground, side-slopes or when foot placement varies from side-to-side. People
with amputations will be enabled to confidently participate in a wider range of activities. This will enhance their
personal satisfaction thereby improving their quality of life. People using prostheses currently have significant
mobility disability and a high incidence of falls, partly because commercially available prosthetic feet are unable
to meet their day-to-day needs.Current prosthetic feet are designed and optimized for level-ground, forward walking. Consequently,
prosthetists align the prosthetic foot to a single preferred position for this activity. During everyday activities,
including quiet standing, feet are placed in different positions. When the prosthesis user ambulates around
their community, they are faced with many obstacles that do not conform to the level-ground forward walking
paradigm. When people engage in tasks while they walk, or if they have poor limb function, the placement of
the foot becomes less controlled. Thus there is a need to fundamentally rethink prosthetic foot design to
restore adaptability to body-ground position.The innovative approach pursued in this project is to develop the Ankentro which restores spontaneous
adaptability, allowing the prosthesis user to ambulate over various terrains. The novel, spontaneously
adaptable foot allows a range of alignments relative to the ground to accommodate a variety of postures and
gait. This is achieved by specific linkages that respond to environmental forces with predictable results,
moving the center of rotation so that it aligns to the resultant forces. Rather than incorporating compliant
surfaces, which can cause postural and gait instability and higher energy cost, the Adaptable Foot restores
adaptability without sacrificing stability.During the Phase II effort, the project team will develop a new prosthetic foot called the Ankentro that
includes the linkage system resulting from the Phase I milestone achievements and then use that refined
prototype for extended community use and evaluation. Ankentro development includes optimizing the linkage
mechanism, developing a new toe and heel spring, refining foot covering dimensions, and validating the design
with standardized mechanical tests. The clinical evaluations include controlled laboratory tests that challenge
side-to-side adaptability, in parallel with community trials. Quantitative and qualitative outcomes will be
generated to evaluate the clinical benefit of the Ankentro.Project Narrative
Currently available prosthetic feet are generally designed by manufacturers and fit/aligned by
prosthetists to be optimal for level ground walking and are unable to adapt to various terrains
including sloped or uneven ground due to limited ankle range of motion. This lack of
adaptability can lead to severe mobility impairment for people using prostheses because of
unstable contact with the ground, resulting in a lack of confidence in their prosthetic limb and
ultimately reducing their community involvement. We seek to restore confidence and
functionality by creating a prosthetic foot that can spontaneously adapt to the ground surface
geometry and uncertain placement of the foot thereby improving community participation and
quality of life.