The influence of protein concentration on the biotribological properties of the stem-cement interface

The stem-cement interface in total hip replacement experiences fretting wear following debonding under cyclical physiological loading. However, the influence of protein concentration on the biotribological properties of this interface has not been well taken into consideration. In the present study, a series of fretting frictional tests were performed using polished Ti6Al4V and bone cement, lubricated by bovine serum albumin solutions of different concentrations (5%, 30%, and 75%). Surface characterizations of Ti6Al4V pins were conducted by optical interferometer, scanning electron microscope, and Raman spectroscopy. The results show that the friction coefficient decreases with the increase of protein concentration, although the difference is not significant. In addition, bovine serum albumin is adsorbed onto Ti6Al4V surface, forming a protective film to prevent the metal substrate from wear. The elemental and spectroscopic analyses of the film confirm the presence of protein molecules adsorbed on Ti6Al4V surface, with a thickness of 2.5 μm. It is indicated from this study that fretting wear at the stem-cement interface can be postponed by promotion of protein adsorption on the metal surface.