Effect of Albumin Concentrations on Frictional Coefficients of Cobalt-Chromium Femoral Head From Atomic Force Microscopy

Atomic Force Microscopy (AFM) has been widely used to measure frictional properties of diverse materials at the microscopic level [1, 2]. Furthermore, there has been the general agreement that albumin plays an important role as an effective lubricant in the frictional behavior of hip implant materials. Through hip simulator, it has been reported that either boundary or mixed lubrication occurs when bovine serum albumin was used as a lubricant [3, 4]. When lubricants contained proteins of albumin or globulin, the frictional properties of the rubbing surfaces were affected by the adsorption of these constituents on the bearing surfaces of the prostheses [4]. Through macroscopic pin-on-disk measurements, another study in the literature has reported the importance of albumin as an effective lubricant for reducing friction and wear of hip implant materials [5]. Although microscopic AFM measurements are very effective for exploring boundary lubrication of diverse lubricants on joint implants, because the frictional coefficients of bearing surfaces in the joint implants can be measured without being affected by the surface roughness of bearing materials, the effect of boundary lubrications of bovine serum albumin (BSA) on hip implant materials has not been well identified. Therefore, the objective of the present study is to investigate the role of BSA as a boundary lubricant in the lubrication of cobalt-chromium (CoCr) femoral head ten years after total hip arthroplasty (THA) by measuring its frictional coefficients with AFM techniques.