SMART-HIP: Smart bioactive nanocomposite coatings for enhanced hip protheses

Total hip joint replacements have become one of the most successful surgical procedures. Normally the procedure dramatically improves the quality of life for the recipient, eliminating the debilitating pain and restoring mobility. The implant would normally be expected to last for 10 to 20 years, in the standard patient, aged over 60 years old. However, as a result of the success of the procedure, increasing numbers of individuals are requesting this procedure from an ever increasingly youthful population. With increasing life expectancy and this new group of younger patients, the demands on the performance of the prosthesis are ever increasing. Metal on metal prostheses have been shown to be an exciting new area for resurfacing and total hip replacements. These implants have been shown to reduce problems of osteolysis associated with the standard, metal on polymer implant, as well as allowing larger diameter prostheses to be used permitting a greater range of movement and lower risks of implant dislocation. However, problems have been identified related to the biological response to both the metal particles produced following wear and also the metal ion release from both the implant and particles, leading to systemic elevations of Co, Cr and Mo. There is, therefore, a motivation to reduce both the volume of wear particles produced and the total level of metal ions released. This project will develop and evaluate the properties of novel nanocomposite, wear and ion release resistant physical vapour deposited (PVD) bioactive coatings, to meet the rigorous demands of the hip joint application. Performance will be assessed on a hip wear simulator to evaluate the longevity of the surface modifications. The surfaces of the coated components will be fully characterised before testing and at regular intervals throughout the testing protocol. The nanoparticles generated in the hip wear simulator will be isolated and characterised using state-of-the-art analytical methods. In addition to reducing wear and ion release, the nanocomposite coatings will be designed to offer novel multifunctional benefits of self-lubrication, antimicrobial properties and improved bedding in of the bearing surfaces. Novel testing protocols will be developed to assess the biological effects of the wear debris, including cytotoxicity, antibacterial potential and immune modulation. This proposal is a unique opportunity to further develop industry and university collaborations generated by: (1) the interdisciplinary nature of the group; (2) new developments in nanotoxicology; (3) coordinated, multifield testing of nanoparticles, including novel methods of assessing benefits and risks to health of humans from exposure to nanoparticles. This proposal will lead to the development of safer and more durable hip replacements, however, the technology may also be applicable to other joint replacements or any other articulating medical device, including interspinal disc replacements.