Development of plasma-sprayed hydroxylapatite coating systems for surgical implant devices

In orthopaedics, total hip joint replacement has been practiced for many years as a surgical procedure, and has contributed to the return to a normal life for many patients. Several designs and materials have led to the evolution of the artificial joint system. Application of a hydroxylapatite (HA) coating on metallic prostheses improves the stabilization of the implant within bone. The hydroxylapatite coating becomes osseointegrated with bone, and the bond is stronger than bone itself. However, attachment of HA to metallic substrates needs improvement.; This study evaluates the effect, on the implant system, of adding an intermediary bond coat between titanium-based metal prostheses and the top hydroxylapatite coating. Investigations show that adhesion strength of the coating is higher with the presence of the bond coat than with HA alone. Thin coatings exhibit more consistent failure modes than thick coatings.; Long term studies are needed to confirm the beneficial effect of the established chemical bond from the titanium-based substrate up to the HA top coat, and to in-situ bone. More work is also needed to identify the exact nature of the intermediary substances.