The road to better, longer-lasting hip implants may be paved with better lubricants. A team of engineers and physicians recently discovered that graphitic carbon is a key element in a lubricating layer for longer-lasting metal-on-metal hip implants. The ability to extend the life of implants would have enormous benefits, in terms of both cost and quality of life. More than 450,000 Americans undergo hip replacement each year, and the numbers are growing.
A lubricating layer normally forms on metallic joints as a result of friction. Once formed, the layer reduces friction as well as wear and corrosion. This layer is called a tribological layer and is where the sliding takes place. Until now, researchers have not known what the layer was. It had been assumed that the layer was made of proteins or something similar in the body that got into the joint and adhered to the implant’s surfaces. The researchers found that the layer actually consists primarily of graphitic carbon, a well-established solid lubricant, not the proteins of natural joints.
“Knowing that the structure is graphitic carbon really opens up the possibility that we may be able to manipulate the system in a way to produce graphitic surfaces,” said Alfons Fischer, a team member from the University of Duisburg-Essen. “We now have a target for how we can improve the performance of these devices.”
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