Second ACL Injury Rates in Younger Athletes Who Were Advised to Delay Return to Sport Until 12 Months After ACL Reconstruction

Background: Younger patients are at increased risk for anterior cruciate ligament (ACL) graft rupture and contralateral injury after ACL reconstruction (ACLR). Increasing the amount of time between surgery and the resumption of competitive sport may reduce this risk. Purpose: To determine the rates of graft rupture and injury to the contralateral native ACL at 3- to 5-year follow-up in younger patients who were advised to delay a return to competitive sport until 12 months after surgery and compare this with a nondelayed cohort. Study Design: Cohort study; Level of evidence, 3. Methods: The primary study cohort consisted of 142 eligible patients aged <20 years when they underwent their first primary ACLR. All were informed about the risk of further injury and advised not to return to competitive sport before 12 months postoperatively. Return-to-sport status and the number of subsequent ACL injuries (graft rupture or a contralateral injury to the native ACL) were determined at 3- to 5-year follow-up and compared with a historic cohort of 299 patients with ACLR who were not advised to delay their return to sport for a set period. The cohorts were then combined, and injury rates were compared between those who returned to sport before and after 12 months postoperatively. Results: The follow-up rate was 91% (129/142). In the delayed cohort, 63% returned to competitive sport after 12 months (mean, 14 months). Few patients (n = 10) returned before 9 months. In the delayed group, 33% had a subsequent ACL injury; this was not significantly different when compared with the nondelayed group (31% rate), in which a majority (58%) returned to competitive sport before 12 months. Subsequent ACL injury rates were also similar when compared between patients who returned before and after 12 months postoperatively (33% vs 32%, respectively). Conclusion: At midterm follow-up, the overall rates of subsequent ACL injury were high, even for patients who delayed their return until 12 months after surgery. More research is required to identify strategies to reduce the high reinjury rate in younger athletes.