Prosthetic foot and ankle stiffness optimization: Modelling and analysis

Lower limb loss is an increasingly common clinical problem in our society. Along with limb loss, amputees must also learn to use their new prosthetic device for daily activities. This study sought to determine the effects of variable component stiffness of the prosthetic foot on gait measurements. In this investigation, three prosthetic feet and three ankle bumpers were manufactured using three different elastic polymers (Silicone Rubber, Acrylic, and Thermal Silicone). The practical tests were conducted on a subject with a left-sided amputation to determine how various combinations of foot and ankle stiffness influence the gait of unilateral trans-tibial prosthesis users and the tensile test was conducted to determine the mechanical properties required for the numerical analysis. According to the findings, the prosthetic foot according to experimental results that showed the thermal silicone double-axis dynamic prosthetic foot has the highest stiffness value (45.513 N/mm), while the smallest stiffness value (6.859 N/mm) appeared with the silicone rubber double-axis dynamic prosthetic foot. The numerical analysis backs up the experimental analysis, with the maximum stiffness findings discrepancy reaching (5.1 %). the medium foot and soft ankle bumpers are the best for gait analysis. The study showed by using the optimization method that the medium foot and soft ankle bumpers combination prosthetic foot has the highest points regarding stiffness, gait analysis, subject comfort. The soft foot and hard ankle bumpers combination prosthetic foot is the second-best combination. The hard foot and soft ankle bumpers combination prosthetic foot is the last-best combination.