Delaying anterior cruciate ligament reconstruction for more than 3 or 6 months results in lower risk of revision surgery

Background The objective of this study is to investigate the risk of revision surgery when delaying anterior cruciate ligament reconstruction (ACLR) past 3 months or 6 months after injury. Materials and methods A total of 30,280 patients with isolated ACLR were identified in the Danish Knee Ligament Reconstruction Registry and divided into four groups; ACLR < 3 months, > 3 months, < 6 months, or > 6 months after injury. Primary outcome was revision surgery and secondary outcome were objective and subjective clinical outcome. The 2 year relative risk, crude, and adjusted hazard ratio (HR) were calculated. Results Comparing ACLR < 3 months to ACLR > 3 months of injury the 2 year relative risk of revision surgery was found to be 1.81 (95% CI 1.46-2.23; P < 0.001) with an adjusted hazard ratio (HR) of 1.27 (95% CI 1.12-1.44; P < 0.001). Comparing ACLR < 6 months to ACLR > 6 months of injury the 2 year relative risk of revision surgery was found to be 1.61 (95% CI 1.34-1.92; P < 0.001) with an adjusted HR of 1.27 (95% CI 1.15-1.40; P < 0.001). Conclusion The risk of revision ACLR surgery was found to be increased when ACLR was performed within 3 months or 6 months of injury compared with later surgery. The 1 year postoperative objective knee laxity and the subjective patient-related outcome was found to be without a clinically significant difference; however, those with early ACLR (< 3 months or < 6 months) were found to have a higher activity level 1 year postoperatively. The information about increased risk of revision when having early surgery should be informed to patients when deciding timing of ACLR treatment. Level of evidence: II.