PROJECT SUMMARY/ABSTRACT In individuals with a unilateral leg amputation, protecting the health of intact anatomy is critical for minimizing secondary comorbidities (e.g., residual leg pain, secondary amputation) that compromise their quality of life. An important indicator of soft tissue health is skin temperature. Tissues exposed to high temperatures can be a source of discomfort and increase risks for pressure sores or ulcer formation, specifically in vulnerable sites such as the intact foot and residuum tissue at the socket interface. Temperature regulation is especially problematic for prosthesis users with diabetes (i.e., the most common cause of amputation in the US) who have impaired vascular function to dissipate heat. There is currently limited knowledge of the mechanisms driving abnormal temperature of affected areas (intact foot, residuum tissue), with or without the influence of diabetes, which hinders early diagnosis of soft tissue complications and interventions aimed to mitigate risks. Recent studies in healthy adults and individuals with diabetes but without an amputation suggest that foot temperature responses are correlated to mechanical factors (e.g., shear forces and work) during walking. Similar studies on unilateral prosthesis users will reveal if the intact foot has elevated risks for tissue complications, especially given their tendency to rely more on the intact leg for daily walking tasks. However, it is currently unknown whether the same mechanical-thermal relationship applies to the residuum tissue within the prosthetic socket, which must assume load-bearing functions similar to the feet. Furthermore, it is unknown how poor vascular function due to diabetes exacerbates thermal regulation in high-risk areas (e.g., intact foot and residuum tissue) in prosthesis users. This proposal will strive towards a unified understanding of the mechanisms underlying thermal regulation in individuals with a leg amputation, including mechanical (Aim 1) and vascular physiology (Aim 2) factors. As a translational benchmark, Aim 3 will determine the effectiveness of a modular prosthetic shock-absorbing component, previously shown to reduce forces and work on the residual and intact legs, to reduce risks for tissue complications that arise due to impaired temperature regulation.

PROJECT NARRATIVE Individuals with a leg amputation are particularly vulnerable to secondary complications, such as pain in the residual limb or tissue damage on the contralateral intact leg – all of which significantly degrades mobility and quality of life. These secondary complications are especially concerning for individuals with diabetes who have impaired vascular function to regulate tissue temperature, a known indicator of tissue health. Our proposal will uncover the mechanisms of tissue thermoregulation, integrating biomechanical and vascular physiology analyses to understand the factors that contribute to tissue complications in individuals living with an amputation.