Evolution of an Adaptable Prosthetic Foot Design for Normalization of Biomechanics During Community Participation Summary/Abstract The 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.
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.
