Ion implantation is a low-temperature vacuum technology that uses a linear accelerator to create a beam of charged atoms, or ions. The ion beam is then shaped and directed toward the device surface, embedding ions into the material.

Current applications include decreased polyethylene wear against CoCr bearing surfaces. Ti-6Al-4V is a softer material than CoCr or bone and fretting wear can be a significant problem on the stems of modular hip and knee prostheses. Ion implantation is used on the stem tapers to reduce fretting wear dramatically. Test results show an order of magnitude reduction in fretting of titanium alloy in micro-motion contact against CoCr.

CoCr femoral hip and knee components cause their mating component of ultrahigh molecular weight polyethylene (UHMWPE) to wear. To reduce wear debris, the CoCr bearing surface is treated. Ion implantation will decrease the coefficient of friction of CoCr against polyethylene, and improve the material's wettability. Improved wettabiliy helps to retain a lubricating boundary layer and reduce wear of polyethylene components. Ion implanted CoCr on UHMWPE wear testing shows virtually no material loss after one million cycles.

“Effect of Low Friction Ion Treated Femoral Head on UHMWPE in
Uncemented THA”, Clinical Orthopedics and Related Research

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