Biomechanical analysis of the diabetic foot: an integrated approach using movement analysis and finite element simulation

Objective:High plantar pressures have been associated with foot ulceration in patients with diabetes. Treatment usually includes an in-shoe intervention designed to reduce plantar pressure under the heel by using insoles. Finite element (FE) analysis provides an efficient computational framework to investigate the performance of different insoles for optimal pressure reduction [Goeske et al. 2005]. The aim of this study is to design a patient specific, 2-dimensional (2D) FE model of diabetic hindfoot and to apply on it patient-specific forces.Method: A 2D FE model of the hindfoot was developed from reconstruction of magnetic resonance images (Simpleware ScanIP-ScanFE, v.5.0 and Rhinoceros v.4.0). FE software ABAQUS was used to perform the numerical stress analyses. A diabetic subject (age, 72 years, BMI, 25.1 kg/m2) and a healthy subject (age 28 years, BMI 20.2 kg/m2) were acquired. The foot biomechanics analysis was carried out as in [Sawacha et al. 2012]. Vertical ground reaction forces (Bertec), taken from the various phases of the gait, were applied to the FE model. Validation of the pressure state was achieved by comparing model predictions of contact pressure distribution with experimental plantar pressure measures Result: A nonlinear 2D FE hindfoot model was developed and meshed with quadratic elements. The measured and model predicted peak plantar pressures of the diabetic subject was respectively 682.32 KPa and 602.82 KPa. The values for the healthy subject were 483.63 KPa for the measured peak plantar pressure and 428.63 KPa for the simulated one. The model predicted structural response of the heel pad was in agreement with experimental results unless 10% of error. Conclusion: The proposed model will be useful to simulate the different insole material and their contribution in decreasing the plantar pressures