Joint effusion at 6 months is a significant predictor of joint effusion 1 year after anterior cruciate ligament reconstruction

This study aimed to assess the risk factors for prolonged joint effusion in patients undergoing double-bundle anterior cruciate ligament reconstruction (ACLR). In total, 160 patients who underwent primary ACLR using autograft hamstring between 2015 and 2018 were retrospectively reviewed. Joint effusion was defined as any grade ≥ 2 (range, 0–3) according to the MRI Osteoarthritis Knee Score (MOAKS). Univariate and multivariate logistic regression analyses were performed. The median age of the patients was 25 years (range 14–68 years) at the time of the surgery; there were 89 women and 71 men. At 1 year, 46 (28.8%) patients experienced knee joint effusion, as defined by the MOAKS. Univariate analysis revealed that age, preoperative Kellgren–Lawrence (K–L) grade, and joint effusion at 6 months were significantly associated with joint effusion at 1 year. In the multivariate analysis, joint effusion at 6 months was significantly associated with joint effusion at 1 year (odds ratio, 68.0; 95% confidence interval, 22.1–209.4). No significant difference in the Lysholm scores was observed between patients with and without joint effusion at 1 year (n.s.). Joint effusion at 6 months was significantly associated with joint effusion 1 year after ACLR. III.