Prediction of stress and strain patterns from load rearrangement in human osteoarthritic femur head: Finite element study with the integration of muscular forces and friction contact

Osteoarthritis (OA) is a degenerative disease that alters the integrity of the joint. Osteophytes represent abnormal osteocartilaginous outgrowths associated with the evolution of OA. Finite element (FE) analysis was performed on an 3D model of the proximal half of human femur to determine the relevance of osteophytes on the stress and strain distributions within the femur head. We assume that the model includes three linearly elastic, homogeneous and isotropic media representing the articular cartilage, the cortical and trabecular bone. With the aim of a more accurate representation of the physiological conditions, we consider in the FE model the influence of the muscle forces that span the hip joint. We also assume a friction contact between the cartilage layer and the cortical tissue. Simulations were carried out for a healthy and three different stages of OA femur. Different load distributions are considered for the four models due to the alterations of bone structure. The patterns of stress and strain within the trabecular tissue suggest that osteophytes manifestation could justify the development of bone cysts (geodes) and the formation of highly mineralized tissue (eburnation). The FE approach presented in this work could result useful in predicting bone behaviour towards abnormal mechanical solicitations.