Wear outcomes of three models of disc prostheses with two bearing materials metal-on-metal and metal-on-polyethylene

Abstract

Wear of facet joints is a significant problem of disc replacement prostheses. We studied the wear behavior of the three models of disc prostheses in five cases, with two choices of bearing materials Metal-on-Metal (MoM) and Metal-on-Polyethylene (MoP). Our aim is to select the main factor that influences on the wear volume results of the disc prosthesis. An axial force of 2000 N combined by an angular displacement of 6° of flexion, 2° of lateral bending and 2° of axial rotation have been applied to the upper plate, the lower plate is still completely fixed. Cases that contain MoM (CoCrMo-on-CoCrMo) bearing materials produced less wear volume compared to the case with MoP (CoCrMo-on-Polyethylene) bearing materials. On the other hand the influence of two other parameters (contact area and nature of core) is low 8.71% between cases 2 and 4 (same bearing material MoP). Therefore, we can say that the three main factors influencing the wear volume are the choice of bearing materials followed by the contact area and the nature of the core (moving or fixed). The fifth case was therefore the model that produced less wear with more degrees of freedom.