[YI-4] Differences in cumulative plantar tissue stress between forefoot regions with and without pre-ulcers in people with diabetes

Plantar foot ulcers are associated with abnormal biomechanical stress during weight bearing, thought to drive formation of pre-ulcers (abundant callus, haemorrhage, blister, skin fissure) before progressing to ulceration. Cumulative plantar tissue stress (CPTS) integrates multiple foot-loading factors into a comprehensive mechanical load measure, but its association with pre-ulcers across all forefoot regions remains poorly understood. This study aimed to investigate whether CPTS differs between forefoot regions with and without pre-ulcers in people with diabetes at high foot ulcer risk.
We included 147 participants (Mean age 66.1±9.5 years, BMI 29.7±5.2 kg/m², 91% type 2 diabetes) with diabetes at high foot ulcer risk. CPTS was calculated per forefoot region (MT1, MT2–3, MT4–5, hallux) by integrating in-shoe and barefoot plantar pressure–time integrals with daily weight-bearing activity measured over seven consecutive days. Mann-Whitney U tests compared CPTS between regions with and without pre-ulcers. In total, 139 of 1,282 forefoot regions presented a pre-ulcer (10.8%). CPTS was significantly higher at pre-ulcer regions at all four sites: MT1 (0.70 vs 0.44 GPa·s/day, r=0.55), MT2–3 (1.02 vs 0.52, r=0.50), MT4–5 (1.32 vs 0.51, r=0.62), and hallux (0.49 vs 0.29, r=0.48).
CPTS was significantly higher at all forefoot regions with pre-ulcers, supporting the mechanical pathway of plantar foot ulceration across all forefoot sites including the hallux.