Foot Biomechanics Model for Diabetic Ulcer Prevention

Objective: High plantar pressures have been associated with foot ulceration in patients with diabetes. Therefore, characterization of elevated plantar pressure distributions can help identify diabetes patients at risk of foot ulceration. Finite element (FE) monitoring of internal deformations and stresses in the plantar pad is required to identify elevated deformation/stress exposures. The aim of this study is to design a patient-specific, multiscale FE model of a diabetic foot. Method: A three-dimensional (3D) multiscale FE model that couples a biomechanical foot model (BFM) and a biological tissue model (BTM) was developed. The BFM quantifies the links between internal structures and external pressures on the foot. The BTM considers the ulcerated region, composed of a necrotic core and a more peripheral zone containing the surrounding soft tissues. The BFM was developed from 3D reconstruction of magnetic resonance images (Simpleware ScanIP-ScanFE, v.5.0). Finite element software ABAQUS was used to perform the numerical stress analyses. A diabetes subject (age 72 years, body mass index 25.1 kg/m2) was acquired. Foot biomechanics analysis was performed. Ground reaction forces (Bertec), taken from the midstance phase of the gait, were applied. Validation of the pressure state was achieved by comparing model predictions of contact pressure distribution with experimental plantar pressure measures (Imagortesi). Result: A nonlinear 3D FE foot model was developed and meshed with tetrahedral elements. The modelpredicted structural response of the plantar pad was in agreement with experimental results. Conclusion: The development and validation of the proposed methodology will be a relevant contribution in increasing knowledge regarding the biomechanical alterations resulting from diabetes.