A novel approach to the estimation and application of the wear coefficient of metal-on-metal hip implants

• A general approach is proposed for estimating two wear coefficients for a coupling.
• The novel approach was implemented in a numerical wear model of MoM hip implants.
• Experimental wear volumes of MoM implants were collected from the literature.
• Two wear coefficients were computed for estimating separate head/cup volume losses.
• The wear coefficients show high sensitivity to implant geometry and test conditions.

A novel approach is proposed to estimate and model the wear of metal-on-metal hip implants. The approach is based on two distinct wear coefficients for the head and cup, derived from separate measurements on the two components. This is in contrast to the usual assumption that a single wear coefficient (k) is valid for both bodies. Actually, the head and cup do not wear equally; thus, assuming equal wear leads to predictive errors. Additionally, in most papers, k is chosen considering only implant materials while neglecting geometry and testing conditions. It is suggested that experimental procedures designed for hip implants should measure the head and cup volume losses separately and that wear maps should be provided to validate numerical models.