Biological Response to Particulate Debris: In Vitro and In Vivo Studies

In this study, we compared the results of a human monocyte in vitro model and a canine in vivo model, to evaluate the response to different types of particulate wear debris. Both the in vitro and in vivo studies demonstrated that titanium-6 aluminum-4 vanadium (TiAIV), ultrahigh molecular weight polyethylene (UHMWPE) and other particulate wear debris are stimulatory to macrophages and elicit release of several identifiable tnediators involved in periprosthetic inflammation and bone resorption. Further, in the in vivo studies, these same particles initiated the formation of interfacial membranes which were histologically and biochemically similar to those seen in clinically failed joint arthroplasties. In vitro models using monocytes are thus useful for studying individual species response to different types of particles. In vivo models have the advantage of accounting for multiple cell types and paracrine effects.