New Surface Treatment to Reduce Alumina Coverage of Grit-blasted Implants

INTRODUCTION For more than 20 years alumina-blasted surfaces have been successfully used for cementless surgical implants, because of their good biocompatibility and rapid osseointegration. However, it has been shown recently that grit-blasting leads to partial embedding of aluminum oxide particles that can cover 24% to 40% of the surface, with a difference between manufacturers [1-2]. These particles can invade the joint space when dislodged and result in third body wear of the articulating surface [3]. The examination of inlays from retrieved metal-polyethylene pairings combined with alumina-blasted implants confirmed the presence aluminium oxide particles which were pressed into the PE [2]. Usually both inlay and ball-head showed scratches which could increase wear and metal ion-release. It is known that cobalt-based alloy wear particles, as well as PE wear particles, can lead to a pronounced foreign body reaction with all signs of an immune response [3]. Therefore, there is a need to develop a method which can reduce or substantially eliminate the hard particles covering grit-blasted surfaces without affecting the existing topography. The combination of topographies in the micrometer and nanometer range has shown to influence significantly the biological performance of implantable titanium devices in orthopedic medicine and dentistry. The efficacy of four different surface treatments to reduce alumina coverage is presented regarding surface coverage, surface topography and surface roughness.