MultiKeel Passive Prosthetic Foot Design Optimization Using the Lower Leg Trajectory Error Framework

Abstract

People with lowerlimb amputation in low and middleincome countries (LMICs) lack access to adequate prosthetic devices that would restore their mobility and increase their quality of life. This is largely due to the cost and durability of existing devices. Singlekeel energy storage and return (ESR) prosthetic feet have recently been developed using the lower leg trajectory error (LLTE) design framework to provide improved walking benefits at an affordable cost in LMICs. The LLTE framework optimizes the stiffness and geometry of a user’s prosthesis to match a target walking pattern by minimizing the LLTE value, a measure of how closely a prosthetic foot replicates a target walking pattern. However, these lowcost singlekeel prostheses do not provide the required durability to fulfill International Standards Organization (ISO) testing, preventing their widespread use and adoption. Here, we developed a multikeel foot parametric model and extended the LLTE framework to include the multikeel architecture and durability requirements. Multikeel designs were shown to provide 76% lower LLTE values, compared with singlekeel designs while withstanding ISO fatigue and static tests, validating their durability. Given their singlepart 2D extruded geometries, multikeel feet designed with the extended LLTE framework could be costeffectively manufactured, providing affordable and durable highperformance prostheses that improve the mobility of LMIC users.