Friction pair evaluation of cartilage–diamond for partial joint repair

Alternative approaches to replace total joint replacement are desirable to reduce the massive loss of healthy tissues. The tribological performance of the cartilage–diamond contact in deionized water and calf bovine serum environments was investigated in this study. To optimize lubrication, hydrogen and ammonia treatments were applied on diamond surfaces. Adhesion and wettability on the same were evaluated to determine the impact of functionalization on surface properties. It was found that the friction between the cartilage and diamond decreased with an increase in the load. This is related to the interaction between two contacting surfaces. Under dry conditions, the hydrogen treatment enabled a reduction in friction while the ammonia treatment increased it. The lubricated friction, however, is determined by two effects: the surface area covered by the lubricant and their interactions. Our results show that the microcrystalline diamond without functionalization provided the lowest friction (coefficient of 0.02–0.03) while sliding against cartilage in serum. The reason is that microcrystalline diamond attracts more molecules that dominate the lubricating performance. This research demonstrated that diamond materials could be suitable as implants as well as to locally repair them.