Diabetic foot represents a complication of diabetes that can lead to foot ulcers and other serious conditions. 3D Finite Element (FE) analysis enables dynamic characterisation of different loads within the foot. This study developed a subject-specific 3D FE model of a diabetic neuropathic and a healthy subject’s foot from MRI data. Experimental analysis of the biomechanics of the foot was combined with FE simulations of foot models generated in Simpleware software. Subject-specific kinematics and kinetics data acquired during gait analysis were used in the simulations. The results obtained from the experimental and simulated studies can help researchers to better understand the aetiology of the diabetic foot.
Guiotto, A., Sawacha, Z., Guarneri, G., Avogaro, A., Cobelli, C., 2014. 3D finite element model of the diabetic neuropathic foot: A gait analysis driven approach. Journal of Biomechanics, 47(12), 3064-3071.
Experimental analysis of the foot was conducted on ten healthy and ten diabetic neuropathic subjects, and hindfoot, midfoot, forefoot, subsegments and tibia 3D kinematics were estimated together with 3D foot subsegments kinetics and plantar pressure (PP). The geometries of the healthy and diabetic feet were then obtained using an MRI scanner (Philips Achieva; Siemens Avanto).
Data was loaded in Simpleware ScanIP and segmented into 30 bones, cartilage and skin, generating a 3D model of the whole foot and ankle. The phalanges of the foot were separated from the metatarsals, and the plantar fascia, Achilles tendon and short plantar ligaments were inserted within the model.
A FE mesh was generated in Simpleware +FE using tetrahedral elements. The mesh included conforming interfaces, resulting in no gaps or overlaps between parts of the model. The +FE Free algorithm was used with a minimum and maximum edge length of 6/8 mm and a 0.4 target maximum error. The final mesh was exported directly to Abaqus (v.6.12).
A horizontal rectangular element was drawn in Abaqus under the foot to simulate ground support. Material properties were adapted from the literature, and the diabetic foot modelled with increased stiffness values for the soft tissues. Four different loading conditions and foot positions were applied to the foot, and run with the prepared kinematics and kinetics data. Validation of the models was carried out by comparing experimental plantar pressures (PP) and the simulated ones.