Effect of sterilization on the structure and fatigue resistance of medical grade UHMWPE

Ultra-high molecular weight polyethylene has been used as the articulating surface in total joint replacements for over three decades. These polymer inserts are sterilized by gamma irradiation prior to implantation. Irradiation is known to alter the structure and properties of the UHMWPE over time. Understanding the evolution of these properties is critical for life prediction of the component. In fact, fatigue-related wear debris currently limits the life of the total joint replacement. In this study, we determine the effect of gamma irradiation on the polymer structure using transmission electron microscopy. Cyclic compression and cyclic tension fatigue tests are performed to establish a link between the structure and fatigue fracture resistance of the polymer.