Pressure and contact area in the coxofemoral joint during activities from finite element parametric modelling

The determination of pressure and contact area distributions in the coxofemoral joint during activities of daily living is essential to predict joint degeneration and prosthesis wear. This can also provide biomechanical justifications for preoperative planning and postoperative rehabilitation. To study the temporal evolution of pressure fields and contact areas in a person's coxofemoral joint during different activities, a parametric finite element model of the joint is developed. Eight activities of daily living are studied. Two different laws of cartilage behaviour are used: elastic and hyperelastic. The results obtained focused on a single subject are compared with those of other studies using classical hypotheses: no labrum, synovial fluid and bone deformability neglected, ideal spherical geometry of the articular surfaces and frictionless contact. The results show that activities related to sitting in and getting up from a chair are the least burdensome activities for the hip joint. Alternation between the bipodal station and the monopodal station is the most restrictive activity. For most activities, the highest pressures are in the anterolateral upper region of the femoral head and in the antero-superior region of the cotyloid. For the activities studied, considering the hyperelasticity of cartilage does not generate a significant difference compared to a simple elastic behaviour. The results are globally in agreement with numerical and analytical models using a spherical model of the joint and quantitatively enrich the knowledge of this field.