Micromotion and friction evaluation of a novel surface architecture for improved primary fixation of cementless orthopaedic implants.

A new surface architecture (OsteoAnchor) for orthopaedic stem components has been developed, which incorporates a multitude of tiny anchor features for embedding into the bone during implantation. It was tested for its ability to provide improved primary fixation compared to existing surface coatings. Friction testing was performed on bovine trabecular bone. It was found that OsteoAnchor provided up to 76% greater resistance to transverse motion under simultaneous normal loading compared to the porous tantalum. Micromotion testing was performed on stem components implanted in cadaver ovine femurs. The micromotion amplitudes for the OsteoAnchor stem were significantly lower than for a corresponding plasma sprayed stem. These results demonstrate that OsteoAnchor has the potential to provide improved primary fixation for stem components in joint replacement operations.