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Topology Optimisation Of Hip Prosthesis To Reduce Stress Shielding


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S. Shuib, M. I. Z. Ridzwan, A. Y. Hassan & M. N. M. Ibrahim


This work presents the application of a topology optimisation method to the hip implant design. A three-dimensional implanted femur is modelled and defined as a design domain. The implant, modelled as type 1, is optimised while other materials i.e. cement (type 2) and bone (type 3), are not being optimised. The domain is subjected to a load case, which corresponds to the loads applied when walking. Loads are employed at the proximal end of the implant and the abductor muscle. Loads from other muscles are not considered. The goal of the study is to minimise the energy of implant compliance subjected to several sets of volume reduction. Reductions are set to be 30%, 40%, 50%, 60%, and 70% from the initial volume (Vo). The result of each set is cut into several sections about x-y plane in z-direction in order to observe the topology inside the stem. It was found that implants with 30% Vo, 40% Vo, and 70% Vo had developed open boundaries whereas 50% Vo and 60% Vo had closed boundary and produced possible shape. Therefore, these designs (50% Vo and 60% Vo) are chosen and refined. Both are analysed using the same boundary conditions as before they were optimised. Results of stresses along medial and lateral line are plotted and compared. Keywords: topology optimization, hip prosthesis, stress shielding, FE analysis. 1 Introduction Over 800,000 artificial hip joints were implanted worldwide annually suggesting that it is a well-accepted and successful treatment [1]. The surgical procedure involves removing parts of the hip joint that have been damaged and replacing


topology optimization, hip prosthesis, stress shielding, FE analysis.