Wear debris and cytokine production in the interface membrane of loosened prostheses

In this study, thirty-nine patients were examined. All of them suffered fro m hip joint prostheses loosening and underwent revision surgery. Bioptic sa mples were collected at the interface between bone and implant either at th e stem or cotyle level. Immunohistochemistry was performed to detect IL-1 a lpha, IL-1 beta, IL-6 and TNF, cytokines that directly cause bone resorptio n and indirectly induce synthesis of other bone resorbing cytokines. Quanti tative analysis of the positive cells and correlation with clinical data wa s performed. It resulted that there is a great variability in positive cells for cytokin es according to the harvest site; anyway, cytokines tend to be higher in pa tients carrying a joint prosthesis with polyethylene acetabular component a nd it is associated with plastic wear particles, even though there is no di rect correlation between wear amount and cytokine levels. There is a statistically significant negative correlation between metal wea r and a cytokine (IL-6); cytokines levels do not depend on the implant time to failure and do not correlate with pain score. As expected, cytokines le vels tend to be lower in subjects being treated with non-steroidal antiinfl ammatory drugs. It can be concluded that plastic wear is the factor inducing the highest cy tokine levels in the tissues around the prosthesis at the interface; cytoki nes that are an indicator of osteolysis risk.