Laboratory studies on the tribology of hard bearing hip prostheses: ceramic on ceramic and metal on metal

Total hip replacements offer relief to a great many patients every year around the world. With an expected service life of around 25 years on most devices, and with younger and younger patients undergoing this surgery, it is of great importance to understand the mechanisms of their function. Tribological testing of both conventional and hard bearing joint combinations have been conducted in many centres throughout the world, and, after being initially abandoned owing to premature failures, hard bearing combinations have been revisited as viable options for joint replacements. Improved design, manufacturing procedures, and material compositions have led to improved performance over first-generation designs in both metal-on-metal and ceramic-on-ceramic hip prostheses. This paper offers a review of the work conducted in an attempt to highlight the most important factors affecting joint performance and tribology of hard bearing combinations. The tribological performance of these joints is superior to that of conventional metal-orceramic-on-polymer designs.