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Diabetic foot ulcers are triggered by mechanical loadings applied to the surface of the plantar skin. Strain is considered to play a crucial role in relation to ulcer etiology and can be assessed by Finite Element (FE) modeling. A difficulty in the generation of these models is the choice of the soft tissue material properties. In the literature, many studies attempt to model the behavior of the heel soft tissues by implementing constitutive laws that can differ significantly in terms of mechanical response. Moreover, current FE models lack of proper evaluation techniques that could estimate their ability to simulate realistic strains. In this article, we propose and evaluate a FE model of the human heel for diabetic foot ulcer prevention. Soft tissue constitutive laws are defined through the fitting of experimental stretch-stress curves published in the literature. The model is then evaluated through Digital Volume Correlation (DVC) based on non-rigid 3D Magnetic Resonance Image Registration. The results from FE analysis and DVC show similar strain locations in the fat pad and strain intensities according to the type of applied loads. For additional comparisons, different sets of constitutive models published in the literature are applied into the proposed FE mesh and simulated with the same boundary conditions. In this case, the results in terms of strains show great diversity in locations and intensities, suggesting that more research should be developed to gain insight into the mechanical properties of these tissues., Competing Interests: Declaration of Competing Interest None, (Copyright © 2023 IPEM. Published by Elsevier Ltd. All rights reserved.)

The role of the above-knee socket is to ensure the load transfer via the coupling of residual limb-prosthesis with minimal discomfort and without damaging the soft tissues. Modelling is a potential tool to predict socket fit prior to manufacture. However, state-of-the-art models only include the femur in soft tissues submitted to static loads neglecting the contribution of the hip joint. The hip joint is particularly challenging to model because it requires to compute the forces of muscles inserting on the residual limb. This work proposes a modelling of the hip joint including the estimation of muscular forces using a combined MusculoSKeletal (MSK)/Finite Element (FE) framework. An experimental-numerical approach was conducted on one femoral amputee subject. This allowed to i) model the hip joint and personalise muscular forces, ii) study the impact of the ischial support, and iii) evaluate the interface pressure. A reduction of the gluteus medius force from the MSK modelling was noticed when considering the ischial support. Interface pressure, predicted between 63 to 71 kPa, agreed with experimental literature data. The contribution of the hip joint is a key element of the modelling approach for the prediction of the socket interface pressure with the residual limb soft tissues., (Copyright © 2022. Published by Elsevier Ltd.)