Ceramics for human clinical use

Osseointegration of alumina with a bioactive coating under load-bearing and unloaded conditions

The aim of the study was to evaluate the osseointegration of Al(2)O(3) coated with a bioactive glass ceramic (BioveritI), in a load-bearing implant model in sheep in comparison to uncoated Al(2)O(3) and to a minimally loaded situation. Both types of implants were inserted into the proximal tibia (load-bearing model) and in a drill hole defect into the tibia diaphysis (minimally loaded model). Under load-bearing conditions, the coating resulted in significantly higher interfacial shear strength and a high amount of mineralized bone in direct contact to the implant surface. In contrast, the uncoated Al(2)O(3) was surrounded by a thick connective tissue layer corresponding to low interfacial shear strength. In the minimally loaded model, however, there was rather a tendency of lower interfacial shear strength in the case of the coated implants. This finding corresponds to the histological results, which showed mineralized bone in the interface of uncoated Al(2)O(3), whereas in the case of the coated implants a thin layer of osteoid was observed. It was suggested that the osseointegration of Al(2)O(3) could be improved by the coating under load-bearing conditions, under which uncoated Al(2)O(3) ceramics cannot directly bind to bone.

A review of metallic, ceramic and surface-treated metals used for bearing surfaces in human joint replacements

A review of established and advanced materials used for the bearing surfaces of total hip replacements (THRs), their standards, methods of manufacture and corrosion testing is presented. Some account is also taken of parallel developments in femoral components used in total knee replacements (TKRs). Metallic, ceramic and surface-modified metallic materials are separately reviewed, but wherever possible common practices are collated. Coated implant bearing surfaces are in an advanced state of development and some designs are receiving clinical evaluation. To date, however, no standard methods of manufacturing and testing these materials have been agreed. Accordingly, corrosion and other key quality test methods suitable for surface-modified implant bearing materials are reviewed.