The predictive value of cumulative plantar tissue stress on future plantar foot ulceration in people with diabetes-A 12-month prospective observational study.

AIMS: Plantar foot ulcers are a burdensome complication of diabetes caused by abnormal foot biomechanics. Predicting foot ulcers aids in their prevention, but the value of peak pressure-the most used biomechanical parameter-is only moderate. We aimed to improve prediction based on the more comprehensive load measure cumulative plantar tissue stress (CPTS). METHODS: We prospectively observed 60 participants with diabetes at high foot ulcer risk for 12 months. At baseline, we assessed demographic and clinical characteristics-including plantar pre-ulcers (i.e., abundant callus, haemorrhage, blister, fissure)-and measured barefoot and in-shoe plantar pressures during walking and standing. Daily-life weight-bearing activity and adherence to prescribed footwear were assessed over 7 days after baseline. The primary outcome was plantar foot ulceration during the 12-month follow-up. CPTS was calculated (in GPa.s/day) from the above foot-loading factors and analysed for predicting foot ulcers and its association with pre-ulcers, using multivariate regression analyses. RESULTS: Twenty-two participants (37%) developed a plantar forefoot ulcer. CPTS was not a significant predictor (odds ratio (OR) = 0.90 (95% confidence interval (CI): 0.50-1.59)) but pre-ulcers at baseline (OR = 9.97, 95%CI: 1.41-70.65) and walking speed (in m/s) (OR = 0.01, 95%CI: 0.00-0.32) were. CPTS was significantly associated with pre-ulcers (OR = 2.38, 95%CI: 1.02-5.54). CONCLUSIONS: CPTS did not predict plantar foot ulceration in our high-risk participants, but our findings support the mechanical pathway of plantar foot ulceration through pre-ulcer development and indicate lower walking speed as an important predictor. Assessing walking speed and early identifying and treating pre-ulcers will help predict and prevent plantar foot ulcers in high-risk people with diabetes.