Finite Element Analysis Of Custom-Prosthesis For Femur-Tumour Treatment

Femur is one of the most common locations of metastatic or myeloma lytic lesions. The complete tumour resection namely edge resection can be given for surgical treatment, and this causes large bone lost. Custom-prosthesis of hip joint replacement is one of the key methods to repair the bone lost and reconstruction the limb function, but it can also lead to the prosthesis breaking and loosing which due to the stress shielding in the long term.With the development of computer, the finite element method (FEM) and computer graphics, the computer aided engineering technology based on numerical simulation are increasingly employed in medicine field. As FEM has advantages on analyzing the mechanical property of anomalous objects, it is extending applied in human bones, especially in the biological mechanics of the hip joint replacement and the optimization of new prosthesis design. In this study, with constructed three-dimensional femur, three cases of the length of bone section corresponding with different length of limb stem are determined and analyzed for the stress distribution on bone, cement and prosthesis respectively. The results of simulation will give surgeons useful suggestions about the scheme of operation.The FEA results show: the max stress of prosthesis stem occurs at about one of three lengths far away bottom stem, less than the limit. Stress on medial and lateral femur is obviously higher than one on anterior and posterior femur, and displays to be increasing gradually from top to bottom. The max magnitude occurs at the bottom of limb stem. Simultaneously, proximal medial cement and bottom lateral cement got higher stress magnitude than other positions.The simulation mentioned above made several conclusions: 1. Putting in prosthesis produces stress shielding phenomenon on proximal femur, but the change of stem-lengths is independent to the region of stress shielding .2.The prosthesis stem must have a certain length, at least as long as the length of bone section. 3.The long stem prosthesis can reduce the stress magnitude of bone cement bottom, but increase the proximal stress. So short bone section is a better choice.