In situ complement activation by polyethylene wear debris

A frequent long-term complication of total joint arthroplasty is aseptic lo osening, the end result of wear debris accumulation, synovitis, and osteoly sis about the implant-bone or cement-bone interface. Complement, an effecto r system in plasma, synovial fluid, and tissue, has powerful chemotactic, i nflammatory, and osteoclast-activating potentials. This study explored the complement-activating ability of polyethylene, a material used in joint Imp lants. In vitro hemolytic assays using sheep red blood cells (E-sh), human serum, and particulate polyethylene suggested alternative pathway complemen t activation, as well as polyethylene adsorption of activated complement co mponents. These results were confirmed by enzyme-linked immunosorbent assay (ELISA) quantification of activated complement factors Bb and C3b. In situ double antibody immunoperoxidase staining for factors Bb, C3a, iC3b, and S C5-9 in synovial tissue from revision hip specimens showed localized altern ative pathway activation and component adsorption. These results introduce a likely role for complement activation in particle-mediated recruitment, p roliferation, and activation of macrophages during early events in osteolys is and implant loosening. (C) 2000 John Wiley & Sons, Inc.