Awarded NSF grant to study ankle-knee coupling dynamics, lower-limb prosthetics
The objectives of this funded research are (a) to characterize the effect of gastrocnemius-like ankle-knee coupling dynamics on human walking, then (b) to test the hypothesis that restoring this coupling for individuals with transtibial (below knee) amputation will improve their gait symmetry and economy while also reducing unhealthy joint loading. This 3-year project will be carried out in collaboration with co-investigators Michael Goldfarb (Vanderbilt), Gerasimos Bastas (Vanderbilt University Medical Center), Steve Collins (Carnegie Mellon) and Josh Captuo (HuMoTech).
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1705714
Extended Summary
Despite advances in prosthetic foot technology over the last decade, there is growing evidence that individuals with lower-limb amputation (ILLA) are still at a physical disadvantage based on how prosthetic feet are attached to the leg. ILLA’s are missing a physical coupling between their prosthetic ankle and biological knee joint. In non-amputees, this ankle-knee coupling is provided by the gastrocnemius (calf) muscle, which helps a person to transfer power from their ankle to the rest of their body. But this important coupling mechanism is cut during transtibial amputation, which may prevent ILLA’s from being able to effectively use power provided by their prosthetic foot. This then forces ILLA’s to change their gait in such a way that it may increase their risk of secondary health impairments. The purpose of this research is to test if restoring ankle-knee coupling with an artificial gastrocnemius will improve the way power is transferred from the prosthesis to the body, and thereby improve health and mobility outcomes for ILLA’s. First, this study will focus on identifying optimal artificial gastrocnemius properties, for use with both passive (carbon fiber) and powered (motorized) prosthetic feet. Next, the researchers will compare ILLA walking with vs. without the artificial gastrocnemius. During this portion of the study, biomechanical measurements will be used to assess benefits. The proposed artificial gastrocnemius design will be lightweight and comfortably fit underneath clothing, such that it can be easily integrated with existing prosthetic feet to broadly impact the health and mobility of ILLA. Improved outcomes may then help to reduce secondary health comorbidities that contribute to >$8 billion in amputation-related medical expenses in the U.S. each year. The research team brings together interdisciplinary expertise in biomechanics, prosthetic design and clinical care, and students will be involved in all stages of this research.