Ceramic wear debris in total joint replacements: review of debris morphology and biological response

摘要

Major long-term complication of total hips has been the high risk of osteolysis in the more active patients. Osteolysis is a result of the biological response to the wear debris particles. This has promoted the search for improved bearings such as new polyethylenes, all ceramic, and all metal total hips. In general, non-cemented all-ceramic total hip replacements appear to be immune to osteolysis, even after twenty or more years experience. In recent years, there has been new information on the biological response to various types of wear debris. Factors such as number of particles, particle morphology (size and shape), and surface to volume ratio are becoming key to the still partial comprehension of this biological response. Recent studies have demonstrated that smaller particles (<0.1 microns) may be more toxic to cells than larger particles (>0.1 microns). Laboratory studies have shown that crosslinking of polyethylene reduces the size of the wear particles proportional to the radiation dose. Therefore, large reductions in wear-rate may not necessarily mean less osteolysis if the particle morphology also changes. Thus, the two factors, which interact, are the volume rate of wear and the morphology of the wear debris particles. Some investigators have developed a biological index (toxicity) of the debris types from cell culture. The purpose of this presentation is to review these three key areas (wear rate, debris, and biological response) and relate them to the performance of all-ceramic total joints in comparison to the polyethylene and all-metal systems.