Comparaison entre la fusion laser sur lit de poudre et l’usinage pour la fabrication d’implants du fémur proximal en acier inoxydable 316L

Abstract

Coxa vara and coxa valga deformities are hip anomalies detected in children and treated with bone correction plates, following the surgical intervention of osteotomy. Essentially made of 316L stainless steel, these plates are machined until the final form is obtained. They are more likely to break during the 3 months following the intervention, the required time for bone consolidation. Hence, the choice of a resistant alloy is challenging. The advent of Laser Powder Bed Fusion (LPBF) provides industry with an alternative to machining, by shaping material additively rather than removing. This technology presents different challenges compared to machining, but its ability to customizing parts with comparable mechanical properties made it interesting for the biomedical industry. The project was born from the collaboration between the Memory Alloys and Intelligent Systems Laboratory (LAMSI) of the Ecole de Technologie Supérieure in Montreal, and Pega Medical, a bioengineering company based in Laval. The characterization of the alloy allowed to determine the optimal manufacturing parameters, the post treatments to follow, the density of printed parts, the uniaxial tensile properties and the microstructure. All these data were extrapolated to compare the two processes in the context of use of the correction plate. This study showed that the fatigue resistance of printed plates (in stress relief state) tested in an adapted configuration of the ASTM F384 standard is better than that of machined plates. They survive a greater number of cycles and at a higher level of load, due to their high resistance and ductility. On the other hand, manufacturing is more expensive and requires more steps, and therefore, manufacturing lead time.

Date	19 Dec 2022
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Vladimir Brailovski (Supervisor)