Improvements in orthopaedic implants
The implants, depending on the composition of their material, can be either bio-inert or bioactive and completely resorbable. Certain compositions of bioceramics and composites have the ability to form a strong direct bond with the host bone. This is mainly due to the formation on their surfaces of a biologically active layer of hydroxylapatite, a calcium phosphate compound, which is the essential mineral component of bone. A group of European universities and companies have developed a low cost knee implant, which demonstrates both longer life and improved osteointegreability. Various methods for the high power laser surface processing were explored before a well-adhered bioactive coating was produced. Essentially, the resulting calcium phosphate coating shows a graded interface between the titanium substrate and a calcium titanate coating, which at the outermost surface is hydroxylapatite. The best means to this end has been proved to be the Nd:YAG laser surface cladding. In-vitro and in-vivo tests demonstrated that the Nd: YAG laser clad coatings have better cytocompatility and less cytotoxicity with regard to the CO2 laser produced samples. Furthermore the Nd: YAG laser clad was proven to perform statistically comparable to standard plasma sprayed materials. However, at the same time, the cost of the implant is significantly reduced by the introduction of simpler design and instrumentation. Innovative three dimensional CAD/CAM and Real Virtual Real Technologies have been developed and used in order to model, simulate and automate the design and manufacturing of the prosthesis and its coating. The resulting cost reduction makes the industrial production of the Nd:YAG laser cladding process feasible, at the same time offering a significant opportunity for further research in either methodology or device development.
