Stiffness is a key feature of modern prostheses and new prosthetic systems can vary this property between steps. Previous work has shown prosthetic stiffness effects center of mass (COM) mechanics, metabolic cost, energy return, and sound-side knee flexion. These factors contribute to overall community mobility, which is a strong predictor of quality of life for amputees. While these studies provide insight, they are limited in the stiffnesses analyzed, and few studies investigate compensatory behaviors and non-steady-state walking. In order to understand the benefit of new technologies that can vary stiffness between steps, we must analyze how changes to stiffness effect biomechanics and mobility. The purpose of this study is to identify an optimal prosthetic ankle-foot stiffness that will maximize the ability to perform common ambulatory tasks and minimize the required compensatory contributions from other lower limb joints. We will use a custom quasi-passive ankle-foot prosthesis that has been designed to allow rapid and precision changes in stiffness of the device. The unique design of this prosthesis will allow us to examine the effect of varying stiffness on gait independent of changes in device alignment. We hypothesize that there will be an optimal prosthetic ankle stiffness that maximizes performance across the three ambulatory tasks: steady-state walking, acceleration and deceleration. Our specific aims are: 1) determine the effect of prosthetic ankle-foot stiffness on gait performance (the rate of acceleration or deceleration during these tasks), and 2) quantify compensatory work done by ipsilateral and contralateral lower limb joints. It is expected that each ambulatory task will have a unique stiffness optimum. This study will provide novel information about how prosthetic ankle-foot stiffness effects compensatory behaviors during non-steady-state walking. The results could inform clinical prescription guidelines and improve future prosthesis designs.
|Effective start/end date||6/1/19 → 5/31/21|
- Orthotic and Prosthetic Education and Research Foundation (Agmt 4/4/19)