Additively manufactured femoral stem topology optimization: case study

Abstract

The main problem of femoral stem prostheses is their primary stability after implantation, which is assured by the so-called press-fit implantation. After implantation, the second requirement is to achieve a secondary stability, due to the osseointegration of the prosthesis in the bone of the femur. Additive manufacturing (AM) allows the designer to create tridimensional models that can have a diffused porosity in the contact area with the bone, which could confer significantly higher osseointegration. Furthermore, through topology optimization, the shape of the prosthesis can be improved, in conjunction with significant mass reduction. This work presents our results concerning the topology optimization of a medium length femoral stem, intended to be manufactured by powder bed fusion (PBF). The CAD models have been analyzed through computer-aided simulations concerning their mechanical characteristics, according to the ISO 7206/4 and ISO 7206/6 standards, and were topologically optimized using commercially available software. The CAD models, both original and optimized, have been analyzed concerning their mechanical characteristics. An optimized femoral stem has been obtained, which answers to the ISO 7206/4 and ISO 7206/6 standards, but with a 15% mass reduction.