DEVELOPMENT OF NANOCOMPOSITE COATINGS FOR ORTHOPAEDIC IMPLANTS BY MAGNETRON SPUTTERING

Abstract

Orthopaedic implants and prosthetic devices form an imposing bulk among the invasive surgeries performed round the world today. In 1980, biomedical implants were a viable option for patients in need of joint replacement, but the orthopaedic marketplace was unable to create a strong, permanently fixed, cementless implant. As a result of the demand for a better implant, several strategies were adopted and technologies applied to develop an implant which can flawlessly integrate with the surrounding tissue and the developing bone. Most of these efforts were directed at the level of implant surface or implant-tissue interface.. Coatings have been designed in an effort to impart the implants with superior osseointegrative and antimicrobial abilities. Drug incorporated or hydroxyapatite coated surfaces and combination of these have become popular. However, with increasing instances of instability and delamination of such coatings from the surface of the implants and reports of antibiotic resistance among microorganisms, especially those responsible for post-operation infections in orthopaedic devices, has resulted in newer and more sophistaicated technology being put to use. A novel approach would be to combine inorganic compounds with superior biocompatibility and antibacterial powers. Titanium oxide is a biocompatible and bioactive compound, capable of inducing the formation of apatite, when immersed in physiological fluid. Zinc oxide, besides the importance of zinc ions in the formation of bone and teeth, is also a potent antimicrobial. Thus, a composite coating of these can provide a plausible solution to the problems faced by the orthopaedic implants of the present day. The present work aims at the development of a bioactive, biocompatible and antimicrobial coating for orthopaedic implants and prostheses. This has been accomplished by reactive magnetron cosputtering of titanium and zinc oxides, to form thin films on silicon substrates, which were then investigated for their microstructural, morphological and biological properties.