Friction and wear of the intervertebral disc endoprosthesis manufactured with use of selective laser melting process

Orthopaedic implants, such as intervertebral disc endoprostheses (IDEs) are difficult to manufacture by means of conventional methods because of their complex shape. However, technologies developed in recent years, such as selective laser melting, could simplify this process. Although this method is attractive in both manufacturing and rapid prototyping of IDEs, little is known about their tribological performance. The functional aim of the work is to conduct a tribological evaluation of the ASTM F75 alloy after selective laser melting process and to investigate the viability of the technology in IDE design. The research aim was an explanation of the wear mechanism of bearing surfaces with respect to the reference material.

In this paper, the tribological test results of a lumbar IDE prototype fabricated by selective laser melting and forging is presented and compared. The endoprostheses were fabricated from commercially available ASTM F75 powder using a selective laser melting device. As a reference material, a forged ASTM F1537 LC alloy was used. Comparative wear and friction tests were carried out with the use of a unique spine simulator.

The obtained results confirm the viability of the selective laser technology in endoprosthesis design. Unfortunately, poorer tribological wear resistance of endoprostheses produced by means of selective laser melting (SLM) technology compared with that of the reference material calls into question the possibility of using these technologies in the manufacturing process of endoprosthesis' components exposed to tribological wear.

This paper presents the friction and wear behaviour of the lumbar IDE prototype. The tests were carried out in motion and loading conditions close to those we observe in the lumbar spine.