The assessment of contact areas within the hip joint during activities of daily living is of critical importance to understand why degeneration mechanisms are sometimes initiated. A generic finite element model is developed and constrained with experimental personalized conditions to locate contact areas and determine pressure distribution, both during walking and stair climbing. Bony structures are positioned in relation to each other by using experimental kinematical data. Implemented loading conditions are computed from an inverse dynamic approach coupled with an optimization method. The mechanical behaviour of a healthy hip joint is first simulated. This model is then used as a reference for the evaluation of a pathological mechanical behaviour. Thus, experimental data are collected for a patient presenting a coxarthrosis. The comparison of the pathological and normal behaviours emphasizes that the contact area swept within the osteoarthritic hip joint is limited both during walking and stair climbing.

Despite their large clinical application, the understanding of the effects of foot orthoses on the lower limb kinematics and kinetics is limited. In this context, we propose an advanced musculoskeletal model to assess the influence of foot orthoses in the loading conditions within an osteoarthritic hip joint during gait. Experimental data are collected for a single pathological subject presenting a coxarthrosis (with and without orthoses), and a healthy subject during walking. An inverse dynamic approach coupled with an optimisation method evaluates the forces developed by 14 muscles and the hip contact reaction force. Contact reaction and muscular force magnitudes are closed whether the patient is walking with or without foot orthoses. Nevertheless, contact reaction amplitudes and orientations show differences in relation to those calculated for the healthy subject. The results obtained allow us to formulate some assumptions concerning the causes of coxarthrosis evolution and treatment.

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