Poster 122: RANTES/CCL5 and BFGF Concentration at the Time of Surgery Can Predict Postoperative Stiffness in Patients Undergoing ACLR

OBJECTIVES: Patients undergoing anterior cruciate ligament reconstruction have been shown to be at risk for postoperative arthrofibrosis. Diagnostic biomarkers associated with development of stiffness are unknown. The objective of this study is to identify biomarkers found in the synovial fluid at the time of surgery that are associated with development of postoperative arthrofibrosis in a cohort of patients undergoing anterior cruciate ligament reconstruction METHODS: Patients undergoing anterior cruciate ligament reconstruction were prospectively enrolled. Synovial fluid was collected in the OR prior to surgical incision. A cohort of patients with postoperative stiffness requiring manipulation under anesthesia or lysis of adhesions was identified. Matching of case to controls was performed using a 1:2 pair matching algorithm. Clinical factor-adjusted single biomarker and multivariable models were used to assess the association of biomarkers with postoperative stiffness requiring MUA/LOA. RESULTS: A total of 11 (n = 3 male, n = 8 female) patients undergoing ACLR met inclusion criteria, matched with 21 (n = 6 male, n = 15 female) controls with no significant differences in age, sex, smoking history, or days from injury to surgery. Levels of RANTES were significantly higher in cases versus controls (694.20 [214.75 - 3428.79] vs. 113.04 [32.81 - 517.91]; p=0.034). IL-IRA, bFGF, and RANTES were found to have greatest predictive value by the final stepwise logistic regression model. Independent predictors of increased risk of postoperative stiffness after ACLR included RANTES (OR [95% CI]) (2.28 [1.29 – 5.37]; p=0.019) and bFGF (1.91 [1.07 – 3.99]; p=0.047) according to a multivariable logistic regression model. Only RANTES was a statistically significant predictor of developing postoperative stiffness (OR [95% CI]) (2.59 [1.26-9.07]; p=0.046). CONCLUSIONS: Higher concentrations of biomarkers bFGF and RANTES were found to be predictive of increased risk for stiffness after ACLR. IL-6, VEGF, TIMP1, IL-1RA, MMP3, MCP-1, and MIPB were not found to be associated with postoperative arthrofibrosis.