Development of measurement techniques to identify and characterise diabetic foot ulceration and foot health conditions

Diabetes is a globally prevalent condition, with the associated affects being altered soft tissues and nerve function. These changes result in areas of abnormally high plantar pressures and thus increased susceptibility to ulcer formation and other foot health conditions. Fewer than half of diabetic foot ulcers (DFU) heal, with up to 60% developing an infection and 29-80% requiring some degree of lower extremity amputation within five years [1].

DFUs are significantly debilitating, with associated social and economic pressures that impact both patient quality of life and healthcare services.

Clinical methods of assessment for DFU typically involve visual inspection of the plantar surface together with foam casting to determine plantar topology, both of which neglect plantar pressure and dynamic movement. Other measurement techniques include in-shoe sensing, which use peak plantar pressures to predict risk of ulceration and guide treatment.

Although research has found some-what of a correlation between peak pressure and ulcer formation, plantar shear force has been identified as an influence in DFU formation, in addition to disparities found in their respective locations [2]. Therefore, understanding the shear forces exhibited in the plantar surfaces of diabetic patient's feet could be key to guide better preventative and treatment procedures.

Current measurement techniques are expensive, time-consuming and neglect shear loads. This restricts their application in clinical settings as well as low-resource areas, both in the UK and globally, where the associated challenges of DFUs are amplified.

To address these limitations, research at Leeds has focussed on the development of measurement techniques which can be used to characterise shear loads in barefoot and in-shoe conditions [3,4]. In particular, one approach uses a computer image analysis technique called Digital Image Correlation (DIC) to determine how an insole deforms during walking as a low-cost way to measure aspects of foot loading [5].

The technique has the potential to improve our understanding of DFU formation and how to develop preventative measures, with promise for translation into use within a clinical environment.

This research will extend these approaches, developing novel approaches to transform the current 2D (DIC) analysis into a 3D method capable of determining load profiles from measured strain. This will be a valuable contribution to further understanding of DFU development. The work has clinical relevance in both low and high-resource settings. The research will link with industry partners to explore future translation to broaden impact and clinical benefit.

Aim:

This project aims to develop a robust and clinically appropriate approach to using Digital Image Correlation for the measurement of plantar loads to characterise foot health conditions. Objectives: 1. Development of 3D DIC techniques to capture shod and unshod plantar strain profiles 2. Refinement of materials and methods to enable robust delivery in clinical and low-resource settings

3. Development of inverse-methods to determine load profiles from measured strain data

4. Evaluation of measurement methods through studies in healthy and clinical populations (specifically those with diabetes and Psoriatic arthritis) 5. Develop opportunities to translate research to the orthotics industry and clinical practice 6. Publication of methods and study datasets in the literature