Evaluation of Carbide-derived Carbon (CDC) Surface Modification for the Application of Hip Implants

Total hip replacements (THR) are considered an end-stage treatment for patients with arthritis or rheumatism. As of 2023, over 450,000 THRs are performed annually in the U.S. However, the current average lifespan of a hip implant is 10-15 years. One of the main obstacles is the inferior tribocorrosion behavior of commonly used biomedical alloys that can cause the early failure of hip implants, leading to revision surgeries that may result in further significant complications. In 2001, Dr. Wimmer’s team discovered a graphitic tribolayer on the retrieved hip implants, demonstrating its ability to shield the implant from tribocorrosive damage. Meanwhile, carbide-derived carbon (CDC) invented by Dr. McNallan’s team, was reported to have excellent tribological properties and similar structures to the tribolayer based on Raman spectra. Inspired by these findings, we previously synthesized CDC on Ti6Al4V using gas chlorination and electrolysis methods, and it is verified that CDC prepared using both approaches can protect the substrate material. Nevertheless, some uncertainties remain. Therefore, in this study, we aim to systematically evaluate CDC as a surface modification technique for hip implants. Specifically, the tribocorrosion performance of CDC was tested on a tribometer with sliding and rotation under various electrochemical conditions, revealing that CDC performed better than Ti6Al4V across all conditions. Additionally, to assess CDC’s performance against fretting-corrosion occurring at the femoral head-neck junction, a fretting-corrosion system was designed with small micromotions and used to test. The results showed that CDC presents better fretting-corrosion than Ti6Al4V. Lastly, CDC’s biocompatibility and osteointegration were tested with MG-63 osteosarcoma and RAW 264.7 macrophage cells. CDC was found to be non-toxic, and the introduction of CDC did not significantly impact Ti6Al4V’s biocompatibility performance.