Pathophysiologic Reactions to UHMWPE Wear Particles

Abstract From a clinical perspective, implants for total joint replacement must contribute to a biologically favorable and mechanically stable environment to provide a satisfactory long-term outcome. One of the most important factors determining the success of a total joint replacement is implant wear over time and the associated adverse biologic reactions elicited by wear debris. The most obvious gross, clinical manifestation associated with implant wear debris generation is bone loss (osteolysis typically after 5–10 years), which has been identified as a major reason for implant loosening and the need for revision surgery after total hip replacement. In 1977, a seminal paper by Hans-Georg Willert demonstrated macrophage activation by UHMWPE wear debris that is generated by intended motion of the articulating implant surfaces, and by the movement of the implant against surrounding bone. These initial observations led to numerous studies characterizing the chronic inflammatory response to foreign debris accumulation in periprosthetic tissue. The challenge in assessing the pathophysiologic response to wear debris associated with a joint implant is to accurately characterize UHMWPE wear debris (amount, size, and shape) and the surrounding tissue response at both early and late implantation times.