Effective Multiplicative Formulation for Shape Optimization: Optimized Austin-Moore Stem for Hip Prosthesis

When dealing with multiobjective optimization problems, several difficulties may appear such as computational time and convergence stability. In this work, a multiplicative formulation is developed to solve both difficulties. The application of this strategy is carried out on the hip prosthesis design. Austin-Moore prosthesis has served as a effective implant in the management of femoral neck fracture in elderly. It has been widely used in hospitals and clinic because of its low cost and simple surgical procedure and satisfactory prognosis. The proposed strategy consists of integrating the shape optimization process using a multiplicative formulation to increase the performance of the hip prosthesis. This developed multiplicative formulation is considered to optimize the Austin-Moore model. The resulting model is called Optimized Austin-Moore (OAM). Considering several daily loading cases, the results show a more uniform stress distribution comparing with the classical solid stem. In addition, a significant increase of the stress levels around the metal/bone interface is obtained, that leads to favorable remodeling process.