Lubricating ability of albumin and globulin on artificial joint implants: a tribological perspective

Albumin and globulin proteins are dominant protein components in synovial fluid, and play important roles in the lubrication mechanism of joint prostheses. The present study investigated the lubricating ability of albumin and globulin on ceramic-on-polyethylene joint implants. A pin-on-disk tribometer was used for friction tests where the experimental condition was replicated with a simulated hip joint condition. The experiment was conducted under three lubricating conditions: bovine synovial fluid (BSF), albumin and globulin. Mechanical properties of specimens and physical properties of lubricant were measured before and after the tests. The experimental results show that albumin yielded a lower friction coefficient as compared to globulin. However, both exhibited a higher friction coefficient and wear rate than that of bovine synovial fluid. This study suggests that further tribological investigations on major biological components of synovial fluid should be carried out, which will help optimise implant design.