Preclinical trial of a novel surface architecture for improved primary fixation of cementless orthopaedic implants

•A new surface architecture for orthopaedic implants has been developed.•The surface incorporates tiny claw features for enhancing primary fixation.•It has been tested for bone in-growth in a pilot ovine hemi-arthroplasty study.•Improved primary fixation was observed compared to a plasma-sprayed control.•Excellent bone in-growth was observed, with pores fully filled with healthy bone.

BackgroundA new surface architecture for cementless orthopaedic implants (OsteoAnchor), which incorporates a multitude of tiny anchor features for enhancing primary fixation, was tested in an ovine hemi-arthroplasty pilot study.MethodsTest animals were implanted with a hip stem component incorporating the OsteoAnchor surface architecture produced using additive layer manufacturing and control animals were implanted with stems containing a standard plasma sprayed titanium coating.FindingsIntra-operative surgeon feedback indicated that superior primary fixation was achieved for the OsteoAnchor stems and rapid return to normal gait and load bearing was observed post-operation. Following a 16-week recovery time, histological evaluation of the excised femurs revealed in-growth of healthy bone into the porous structure of the OsteoAnchor stems. Bone in-growth was not achieved for the plasma sprayed stems.InterpretationThese results indicate the potential for the OsteoAnchor surface architecture to enhance both the initial stability and long term lifetime of cementless orthopaedic implants.