Tribological Characterisation of Ceramic and Metal Implants

In Total Joint Replacement (TJR), ceramic surfaces offer a major benefit of drastically reduced wear rates and excellent long-term biocompatibility with the bone tissue. Among the available ceramic materials for load bearing bio-implant applications, silicon carbide is superior for its better biocompatibility, which can increase the longevity of prosthetic joints. The major cause of revision surgery and implant failure is Osteolysis (aseptic loosening of the prosthetic joint). The product of bearing wear, microscopic particulate debris in the joint space leads to implant loosening. Prosthetic joint mainly consists of acetabular cup, acetabular lining and femoral head. The best material for manufacturing acetabular cup is nickel-base alloy. For manufacturing acetabular lining and femoral head, silicon carbide is the best chosen material. The acetabular cup or knee cap is prone to catastrophic failures due to walking, stumbling etc. A sliding distance test was performed on polished surface of silicon carbide and nickel-base alloy (mirror- like finish, 1μm) by using Reciprocating Friction Monitor (Courtesy; National Institute of Technology, Srinagar) for the evaluation of wear volume and wear coefficient by standard test procedures and equation outlined in ASTM F 603. The test was carried out in ambient temperature. The results obtained showed drastically reduced wear rates. The experiments on Reciprocating Friction Monitor for Silicon carbide and nickel –base alloy showed that the best choice for prosthetic joint replacement would be a combination of two materials; silicon carbide for femoral heads and acetabular lining, and nickel-base alloy for acetabular cup.