Biomechanical factors for non-plantar ulcers in diabetic foot disease

ABSTRACT Diabetic foot disease remains one of the most devastating consequences of diabetes, with the development of a foot ulcer, its infection, amputation of the foot, and an increased overall risk of mortality an all-too-common story for these patients. Veterans are more likely to be affected by diabetic foot disease, therefore it is essential that we have a clear understanding of how these ulcers occur. Through wide-ranging in vivo and ex vivo research, an extensive body of knowledge has been developed on the properties of the plantar tissues of the foot and how these alter with diabetes, as well as how these changes increase the risk of ulceration. However, a significant proportion of diabetic foot ulcers occur on other parts of the foot, such as the toes, heel, and dorsum, and our understanding of how wounds at these locations develop and how to prevent and treat them is far less established. The aim of this project is to begin to understand the biomechanical factors behind non-plantar ulcers in diabetic foot disease and lay the groundwork for developing optimized strategies to prevent and treat them. To achieve this, the proposed project will be based around two primary and one secondary aims. In Specific Aim 1, we will develop methods to determine the mechanical properties of foot tissue at common non-plantar ulceration sites. A series of testing protocols will be established to allow the structural properties (including compressive, shear, and frictional) of non-plantar cadaveric tissue to be characterized. Once these methods have been established and validated, non-plantar sites on a pilot set of cadaveric feet (from donors with diabetes and age/sex matched controls) will be tested to provide preliminary data that will help in the design of future experiments. In Specific Aim 2, {eight} individuals with diabetic peripheral neuropathy and {eight} matched controls will have their non-plantar pressures measured in a range of footwear conditions during a series of standing and walking movements based around activities of daily living. This study will provide pilot data for future work aimed at further characterizing these forces and developing interventions to reduce their incidence. Finally, in the Secondary Aim we will review current technologies for shear force measurement regarding their suitability to measure these types of forces, which may play a major role in non-plantar ulcer development, within the shod environment. Overall, the impact of these novel techniques and data on the mechanisms behind non- plantar ulcers could ultimately lead to a step change in our ability to screen for those at high risk of developing an ulcer and could initiate new treatment strategies aimed at preventing or treating these injuries. Given the increased risk the Veteran population is at for diabetic foot disease, reducing rates of ulceration in this group has the potential to greatly lower the incidence of lower-limb amputations and improve the quality of life for our Veterans. The results from this project will directly motivate and inform the submission of a Merit Review application designed to achieve these longer-term goals.