The role of cytokines in inflammatory response after total knee arthroplasty in patients with rheumatoid arthritis

Surgery and trauma is accompanied by changes in blood levels of certain cytokines and chemokines including interleukin-6 (IL-6) and interleukin-8 (IL-8). However, there is little data on correlations between local and systemic levels of these mediators during orthopedic surgeries in rheumatoid arthritis (RA) patients who already show increased levels of proinflammatory cytokines due to their disease. We aimed to measure dynamics of blood and drainage fluid levels of IL-6 and IL-8 in postoperative period in rheumatoid arthritis patients undergoing knee replacement surgery and correlate these changes with blood levels of C-reactive protein (CRP), body temperature and pain. We report that blood and drainage fluid levels of IL-6 and IL-8 showed significantly increasing trend during the 36-h period after the surgery. Drainage fluid levels of both cytokines were significantly higher in comparison with blood, indicating their local production in the operated joint. In contrast, levels of CRP were higher in blood than in drainage fluid. Despite the fact that the levels of tested cytokines had already been high in RA patients before surgery, we conclude that after surgery their levels were being much significantly enough high in drainage fluid to reflect dominated local inflammatory reaction to surgical stress and trauma.