Development of Plantar Strain Measurement to Characterise Diabetes-Related Foot Disease

Diabetes-related foot ulceration is an increasingly prevalent issue in people with diabetes, placing substantial social and financial burden on individuals at risk and on healthcare services managing their care. Ulcer formation has been shown to be strongly influenced by mechanical loading, yet current assessment tools focus primarily on plantar pressure and overlook shear stress. This thesis aimed to develop a 3D Digital Image Correlation based in-shoe system (STAMPS3D), extending the previously developed 2D STAMPS system (a planar strain measurement approach that used Digital Image Correlation to assess plantar load at the plantar interface). By advancing this concept into three dimensions, the work enables measurement of plantar strain across non-planar surfaces to generate clinically relevant information related to ulcer risk.

The research was guided by five research questions, defined through an extensive literature review, which address both the technical feasibility of the system and its clinical relevance. Accordingly, key research topics included the evaluation of measurement performance, validation of the 3D DIC methodology, assessment of the system in clinically meaningful contexts, and incorporation of stakeholder perspectives to understand translational requirements. To address these questions, the project involved validation of the 3D system and proof-of-concept studies applying STAMPS3D to contoured orthoses and simulated callus. Stakeholder discussions informed the selection of these contexts and highlighted practical considerations for future development.

The results demonstrated the system’s ability to capture plantar strain across both planar and non-planar surfaces, with outputs correlating with in-shoe pressure measurements captured using the Pedar system, a commercially available insole pressure device. The proof-of-concept studies showed that STAMPS3D can measure strain across complex contoured surfaces and is sensitive to localised changes introduced through simulated callus. Stakeholder insights aligned with these findings and identified further refinements needed to support clinical translation.

Overall, this thesis establishes the feasibility of a 3D strain-based in-shoe measurement system and provides the methodological foundation required for future clinical studies. The findings highlight the value of strain-based assessment for diabetes-related foot ulcer prevention and management and furthermore outline a clear pathway toward integrating STAMPS3D into future clinical pathways.