Effects of a powered ankle prosthesis on shock absorption and residual limb/socket interface pressure

Abstract

Lower-extremity amputees face potentially serious post-operative complications, including increased risk of further amputations, excessive stress on both limbs, and discomfort at the stump/socket interface. State of the art; passive prostheses have improved many negative consequences associated with lower-limb loss, but we believe the limit of uninformed elastic prostheses has been reached. Further strides require a more biomimetic approach. Through integration of "smart" technology (sensors and actuators), a new phase of bionic lower-limb prostheses is upon us, which enables prosthetic devices to more closely mimic biological behavior by generating human-like responses and power outputs. The closer we come to natural biology, gait abnormalities in amputees will decline. This project compares the first bionic ankle prosthesis to commonly used passive prostheses to determine how more biomimetic adaptability and work generation in the prosthetic joint affects discomfort and joint stress. We have put forth several metrics to describe discomfort (elements of shock absorption, pressure distribution, etc.) and will conduct level-ground walking tests with three unilateral amputee subjects using both passive and power devices. We hope to make a case for the pursuit of more biomimetic designs for rehabilitative devices, by showing a positive effect on "comfort" and a restoration of normal gait dynamics when using a bionic ankle prosthesis.