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

In this study, thirty-nine patients were examined. All of them suffered from hip joint prosthesis loosening and underwent revision surgery. Bioptic samples were collected at the interface between bone and implant either at the stem or cotyle level. Immunohistochemistry war performed to detect IL-1α, IL-1β, IL-6 anti TNF, cytokines that directly cause bone resorption and indirectly induce synthesis of other bone resorbing cytokines. Quantitative analysis of the positive cells and correlation with clinical data was performed. It resulted that there is a great variability in positive cells for cytokines according to the harvest site; anyway, cytokines tend to be higher in patients carrying a joint prosthesis with polyethylene acetabular component and it is associated with plastic wear particles, even though there is no direct correlation between wear amount and cytokine levels. There is a statistically significant negative correlation between metal wear 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 levels tend to be lower in subjects being treated with non-steroidal antiinflammntory drugs. It can be concluded that plastic wear is the factor inducing the highest cytokine levels in the tissues around the prosthesis at the interface: cytokines that are an indicator of osteolysis risk.