Dimensional Characterization of Prosthesis Bearings for Tribological Modelling

Prosthesis bearings are precision mechanical systems from which performance improvement represents a direct contribution to patient’s wellbeing. Spherical shape of hip prosthesis bearing approaches natural ones, but their performance become degraded in service, and the lubrication and wear mechanisms are outstanding fields of research. Because tribological phenomena are complex, attempts of modelling the bearing requires precise consideration of the boundary conditions that the real prosthesis have. Detailed experimental characterization of two ceramic hip prostheses is accomplished. Shape and roughness are measured by accurate point coordinate metrology with proper methodology through contact probing by a coordinate measuring machine, and optical measuring through confocal microscopy. The results quantify the deviation from the ideal shape and significant roughness parameters of bearing surfaces. Their influence is discussed in the spotlight of their relationship with the tribological behavior of the prosthesis. Future works direction are envisioned so geometrical boundary conditions can play an important role in prosthesis performance understanding and improvement.