Structural Optimization of a Total Replacement Hip Prosthesis

Planted articular joints replace bone articulation allowing the transfer of loads and articular displacements. However, hip prosthesis cannot guarantee the same dynamic friction coefficients of natural joints. The present study analyses the main design solutions for hip prosthesis, in terms of geometries and materials and an in-depth bibliographic research was performed to identify the load spectra corresponding to the different operation conditions of the planted joint. The final aim of this study is to analyze the stress state induced in the prosthesis by the mounting effect as well as under the action of loads deriving from ambulation in order to perform a structural optimization which guarantees the needed life time. In order to optimize the chosen prosthesis, the geometry of the three elements constituting the prosthesis was reconstructed through the reverse engineering technique: femoral head, acetabular cup and insert. The geometries obtained were used to implement a finite element 3D model in ANSYS® environment. The results obtained with the finite element 3D model were used as a reference to study the effects of some geometrical parameters of the prosthesis with a simplified model which takes advantage of the geometric axisymmetrical properties of the prosthesis.