Key words: particulates, biological response, wear debris, standards, research
Loosening is the most common mode of failure of total hip and knee arthroplasties. The biological response to wear debris is complex, involving many cell types, including macrophages, which can phagocytize the wear debris. To date, in vitro studies have focused on the release of inflammatory mediators by phagocytic cells in the presence
of particles. The current study uses real-time chemiluminescence to determine the generation of reactive oxygen species by human monocyte-derived macrophages in the presence of different concentrations of commercially pure titanium (CpTi), polystyrene (PS) and polymethylmethacrylate (PMMA) particles. The data indicate that CpTi elicits a weak extracellular (superoxide) response but not an intracellular (hydrogen peroxide) response. PS and PMMA of matched particle number and diameter showed a dose response curve for both the intra- and extracellular reactions. Inhibitors of phagocytosis and superoxide suppressed the chemiluminescence reaction. The differences in the kinetic reactions between CpTi, PMMA, and PS may indicate differences in the uptake and processing mechanisms of the ingested particles.