The Relationship Between Hip Simulator Wear and Surface Morphology Characterized Using White Light Interferometry

A non-contact surface topography measurement system based on white light interferometry was used to quantify the surface morphology of the UHMWPE, PTFE, HDPE, and polyacetal liners before and after wear testing. We investigated the hypothesis that the wear rate of four polymeric materials in the hip simulator was related to quantitative metrics of the surface morphology (i.e., surface roughness). Nine common roughness parameters (PV, R_a, R_rms, R_sk, R_ku, R_tm, R_z, R_3z, and H) were evaluated in 28 acetabular liners. The surface morphology within a given material was reproducible from insert to insert. Statistical relationships were observed between the surface roughness of the acetabular liners and the volumetric wear rate (p < 1 × 10⁻⁶). However, the power law relationships accounted for less than 50% of the variability in the data, based on r².