Anti-inflammatory properties of titanium in sd the joint environment - An experimental study in rats

Little is known about the tissue reactions to various implant materials whi ch coincide with an inflammatory reaction. We used the avridine arthritis r at model to evaluate the tissue response in the synovial, interstitial and subcutaneous tissues after implant insertion. Quantitative immunohistochemistry showed that normal joint synovial tissue is dominated by ED2-positive resident macrophages. Polyethylene implants in duced a much stronger foreign-body reaction than titanium implants, as meas ured by the number of interfacial ED1-positive macrophages. The tissue resp onse to titanium and polyethylene was also vastly different in arthritic sy novial tissue compared with control tissue. It is likely that these biomaterials interact differently with inflammatory cells or intermediary compounds. It may be that arthritic synovial tissue produces reactive oxygen intermediates (free radicals) with which titanium has a unique anti-inflammatory interaction in vitro.