Study On The Design Methods Of Customed Hip Joint And The Contact FE Analyse

The function of the hip joint will lose because of diseases or accident. The effective way at present is to use an artifical joint to replace the natural one if the medicine doesn't work. But the long-term stability of the artificial joint can't turn up trumps, with the aseptic loosening, which lead to the failure of the operation. Many researchers consider that both the mechanics and the biology factors can cause the loosening, for example, the stress shielding and wearing chippings. So it has become a hip subject in the field of medicine and engineering that to solve the loosening, enhance the stability and prolong the life of the joint. This subject is sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars(2001345). The author have done some research works on the design of the custom made endoprosthesis, virtual hip replacement, analyse of the femur-stem contact using the finite element software, and stimulating the femur adaptation with the program in ANSYS parametric design language (apdl for short). Plenty of data have been gotten from these works, which are useful to the prosthesis optimization design. To sum up, the primary study content in this paper is described in the following: 1. According to the CT images of the femur, design the custom made prosthesis. Three methods which are four-lines variable section sweep, center-line multi-sections sweep and straight stem prosthesis have been brought forward. After design the prosthesis, a virtual assembly has been finished to check the relation between the femur and the prosthesis. 2. Rebuild the femur material program using apdl to make sure that the femur's finite element model is anisotropy and the finite element model and the entity model coexist. 3. Before analyze the femur-stem model, summarize the theory about the contact problem, moreover, the definition of contact, parameters's setting and state check up, etc, were emphasized. 4. Start with the stress shielding, 8 models under two gaits have been compared, one is the femur before the replacement and the others are the femur-stem contact models of different design state, such as the length of the prosthesis, material, design method and so on. Von Mises stress and strain of 10 differents measuring points of each model were compared. The result of the compare can be the guidance to the optimization design of the prosthesis. 5. The paper carried out the simulation of femoral self adaptation using the program compiled by apdl and analysed the simulation result.