There are over 1 million Americans with lower-limb loss, and annual U.S. hospital costs associated with amputation are in excess of $8 billion. These lower-limb amputees struggle with mobility-related challenges that degrade their quality of life, by making physical activity more fatiguing, health more precarious, and independent living more difficult. Powered bionic prostheses have been developed to help address some of these mobility and health deficits; however, these powered feet are prohibitively expensive for many amputees. There is a pressing need for lower-cost prosthetic innovations, which can improve amputee walking ability and be accessible to individuals across the socioeconomic spectrum. This research proposal seeks to investigate one potential solution, by exploring how toe joint dynamics can be incorporated into passive prosthetic feet to enhance mobility. Although biological toes are known to be beneficial for walking and balance, little attention has been paid to restoring this important toe function into prosthetic feet. The first goal of this proposal is to systematically characterize the interplay between the ankle and toe joints, since our existing data and understanding is limited. This new scientific knowledge of toe joint dynamics can then be applied to develop prosthetic feet with optimized toe properties that improve amputee walking abilities. This research will address important knowledge gaps in our fundamental understanding of ankle-foot function, and could lead to more affordable and effective foot prostheses that improve quality of life for amputees across the socioeconomic spectrum. Undergraduate and graduate students will be involved in all stages of this research, and targeted efforts will be made to promote inclusion of gender and racial minorities in engineering. Prosthetic science and technology will be integrated into the university curriculum, and this research will be disseminated broadly; for example, through lab tours for local middle and high school students, specifically for community organizations targeting under-represented groups in science and engineering.
The objective of this research is to investigate the dynamic interplay between the ankle and toe joints during bipedal gait, and then assess if a low-cost prosthetic foot with articulating toe joint can improve mobility outcomes for lower-limb amputees. A series of systematic parameter studies is proposed to advance our fundamental understanding of ankle-foot function, which has the potential to spur transformative and affordable prosthetic advances. This research focuses on level ground walking because it is a ubiquitous mode of human locomotion, and critical for daily living. A reconfigurable foot prosthesis will be developed, which allows ankle-foot parameters (e.g., joint stiffness, foot and toe lengths) to be systematically and independently varied. Aim 1 seeks to assess if inclusion of an articulating toe can increase limb push-off capabilities during walking and improve gait economy, and to identify optimal toe properties. Human subject parameter studies will be performed to generate new biomechanical data (e.g., kinematics, kinetics, metabolic rate), which characterize the dynamic interplay between the ankle and toe joints, and the effects on whole-body gait. This will be the first controlled, systematic study of toe parameters, within and beyond natural biological variation. This research will fill an important knowledge gap, and provide the scientific basis for new, low-cost innovations in prosthetic feet. Increased knowledge of ankle-toe interplay could also impact the design of exoskeletons, orthoses and humanoid robots. Aim 2 seeks to perform a feasibility study to test if a prosthetic foot with an articulating toe joint can improve amputee walking performance, by comparing transtibial amputees walking on a passive foot prosthesis with vs. without a toe joint. Assessment will be performed in collaboration with clinical partners, using comprehensive biomechanical analysis and the expertise of rehabilitation physicians dedicated to the care of amputees.
