Evaluating use of a robotic prosthetic foot emulator to test-drive prosthetic feet in people with lower limb amputation: mechanical validation and qualitative interviews

Thesis (Ph.D.)--University of Washington, 2021Selection of a prosthetic foot is an important decision for lower limb prosthesis prescription. Without objective evidence to guide foot prescription, clinicians (i.e., physicians and prosthetists) rely on their expertise to best match a foot to a patient’s functional goals. However, persons with lower limb amputation typically cannot usually try different prosthetic feet before one is ultimately selected. The robotic prosthetic foot emulator (PFE) is a technological advancement that could facilitate a test-driving approach to foot selection, in which the prosthesis user quickly trials several prosthetic feet and then contributes their experiential input to the decision-making process. This dissertation used quantitative and qualitative approaches to assess use of the PFE for test-driving prosthetic feet. First, quantitative procedures to emulate the angular stiffness of commercial feet used in the PFE were developed and validated. Mechanical testing procedures were used to collect angular stiffness data for a variety of commercial prosthetic forefeet. PFE foot profiles were created from these data and mechanical testing was repeated with the emulated feet to evaluate the accuracy of the emulation. Angular stiffness of emulated feet was significantly correlated with that of respective commercial feet. Mean differences in angular stiffness between emulated and commercial feet were less than 1%, and were independent of prosthetic foot type and example foot sizes or intended user body weights. Participants with lower limb amputation (LLA) then used both the PFE and commercial feet to complete a test-driving protocol, before completing qualitative, semi-structured interviews with an investigator. The purpose of the interviews was to develop a grounded theory of the experience of prosthetic foot prescription from the perspective of prosthesis users. The core category was the relationship between knowledge about prosthetic feet and decision-making power. Participants described prosthetic foot prescription as an educational journey. Relationships with clinicians and peers with LLA were recognized as highly valued and capable of influencing the quality of the foot prescription experience. Participants also noted the importance of their individuality and preferences for the extent of being engaged in decision-making. Test-driving accelerated users’ education about feet options and facilitated discussion with clinicians. Therefore, complementary findings from these two studies support the potential for future use of the PFE for test-driving. Further research may be warranted to evaluate the use of the PFE and test-driving to augment prosthetic foot prescription processes