Raffinement d'une nouvelle plaque trochanterienne a l'aide de la methode par elements finis

Greater trochanter (GT) detachment can occur following a fracture or an osteotomy. In all cases, it is imperative to fix the fragment. In the past, different wires or cables cerclage technique were used. Nowadays, cable grip systems are usually used to maintain the GT. But these systems show important issues which can lead to bone healing failure. In order to reduce these problems, a novel concept (Y3) of GT reattachment, using a plate with cable and screw, was developed by the candidate in previous work.;The model represents the femur's proximal part with a GT osteotomy and the Y3 plate fixed using screws to maintain the GT. In concordance with experiments used to validate the model, the lower extremity of the femur is fixed and loads are simultaneously applied to the femoral head and the GT. A sensitivity study of different Y3 plate regions to the GT displacements was first achieved to prepare the iterative refinement steps. The model was then used to refine the plate's size and shape.;Validation results suggest a good agreement between experimental and numerical displacement. Numerical simulations predict displacements in the same direction but smaller in amplitude than experiments. The presence of over-constraints due to reducing assumptions may explain in part the rigid behavior of the model. The results show that the most critical region for GT displacement is where the superior and inferior branches merge together. The plate refinement, completed in 5 iterations, allowed a thickness reduction of 5% in the most critical region and between 25% and 33% for other regions. This decrease in size could have a favorable impact on pain and complication for patients.;Keywords: trochanter, finite elements, reattachment system;The objective of the Y3 system is to reduce the movement between the GT and the femur but also to provide a low profile. A low profile presents the advantage of decreasing the friction between the muscles and the plate helping, reducing bursitis and pain. The "Y" shape of the plate avoiding the GT protuberance is a key element for its low profile. However, the initial concept of Y3 plate seems to be overdesign. The objective of this thesis is to further refine the Y3 plate design using finite elements method.