Measuring In-Shoe Plantar Strain Outcomes in the Presence of Callus: A Preliminary Study Using the STAMPS3D Measurement System.

INTRODUCTION: Diabetes-related foot ulcers (DFU) are growing in prevalence, driven by the global rise in diabetes. Plantar callus has been identified as a risk factor for DFU formation, with its presence considered highly predictive for ulceration. Preventative strategies, such as debridement and offloading aim to reduce the thickness of localised hard skin formed through repetitive high pressure and shear stress. Although several studies have looked at the quantitative effects of callus and its removal in the neuropathic foot, assessments have relied solely on pressure measurements, neglecting the contribution of shear stress. A lack of in-shoe measurement devices capable of measuring shear, either independently or alongside pressure, limits our understanding of how the foot behaves in the presence of callus or responds as a result of debridement.

METHODS: This proof-of-concept study investigates the use of the STAMPS3D system to capture cumulative 3D plantar strain data across the foot in the presence of simulated callus in healthy participants. By introducing multi-layer silicone inserts that replicate key mechanical features of callus at the 1st metatarsal head and heel regions, this study explores plantar strain responses in healthy participants.

RESULTS: The simulated callus produced subtle redistribution of strain across the foot with distinct local changes at the callus sites.

CONCLUSION: Findings may inform future approaches to objective callus assessment, guide debridement practices and contribute to DFU prevention strategies.