Inflammatory cytokine levels in synovial fluid 3, 4 days postoperatively and its correlation with early-phase functional recovery after anterior cruciate ligament reconstruction: a cohort study

BACKGROUND: Synovial fluid was collected prior to and at 3 to 4 days after ACL reconstruction to investigate the correlation between inflammatory cytokine levels in the acute phase after surgery and physical functional recovery at 3 months postoperatively. METHODS: For this purpose, 79 patients with ACL reconstruction using semitendinosus tendons were included in the study. Median days from injury to surgery were 80 days (13–291 days). Synovial fluid was obtained just before surgery and at 3 to 4 days after surgery. Physical activity of each patient was evaluated at 3 months postoperatively, and scored from 0 (hard to walk) to 5 (run). Patients able to jog (score 4) or run (score 5) were considered as the “quick recovery” group and others (scores 1–3) as the “delayed recovery” group. RESULTS: Physical activity recovery scores in the early surgery group (preoperative period less than 60 days; Group I) were significantly better than those in the delayed surgery group (Group II). Among the cytokines tested, TNF-alpha and IL10 levels in synovial fluid were significantly higher in Group II at 3 to 4 days postoperatively, while levels of these cytokines were quite comparable preoperatively between the groups. Increased IL1-beta expression was noted in the delayed recovery group at 3 to 4 days postoperatively. In addition, levels of IL6, IL10 and IFN-gamma also tended to increase in patients with delayed recovery. CONCLUSION: Delayed ACL reconstruction increases levels of inflammatory cytokines in synovial fluid after surgery and correlates with a prolonged recovery of short-period physical activity of the patients.