Investigation of three-dimensional surface topographies and mechanical properties of hypothesized biological active wear particles from artificial joints

Numerical characterization of geometry, topographies and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) wear particles from artificial hip joints provides an insight into the wear mechanisms of the artificial joints. In this study, two types of UHMWPE wear particles, namely, hypothesized bio-active and less active particles, were produced on a six-station pin-on-plate multi-directional wear simulator. Atomic force microscopy (AFM) was used to quantify wear particle features in three dimensions. In addition to the geometric features of the wear particles, comprehensive surface topography investigations were carried out on AFM using numerical image analysis techniques. Furthermore, the nano-mechanical properties of the wear particles were investigated. The results revealed that the hypothesized bio-active particles had a larger aspect ratio and thickness, a rougher surface and a smaller modulus in comparison to the hypothesized less bio-active or bio-inactive particles. The investigations in this study have provided further knowledge to the specific geometries, surface morphologies and mechanical characteristics of the hypothesized bio-active and less bio-active particles, as well as an insight into the particle generation mechanisms. This knowledge can be utilized to minimize particle-related tissue reactions through developing effective methods to control the generation of biologically active particles or to assist in inventing new artificial joint materials.