Background

Younger patients are at increased risk for anterior cruciate ligament (ACL) graft rupture and contralateral injury after ACL reconstruction surgery. Increasing the amount of time between surgery and the resumption of competition sport may reduce this risk. The purpose of this study was to determine the rates of graft rupture and injury to the contralateral native ACL at 3-5 years in younger patients who were advised to delay a return to competition sport until 12 months post-surgery and compare this to a non-delayed cohort.

Methods

The ‘delayed’ study cohort consisted of 142 eligible patients who were less than 20 years when they underwent their first primary ACL reconstruction. All were informed about the risk of further injury and advised not to return to competition sport before 12-months. Return to sport status along with the number of subsequent ACL injuries (graft rupture or a contralateral injury to the native ACL) were determined at 3-5 years and compared with a historic cohort from the same institution who were not advised to delay their return to sport (non-delayed cohort n=299). Patients from both cohorts were then categorized according to whether they had actually returned to competition sport before or after 12 months and subsequent injury rates compared using contingency analysis.

Results

The follow-up rate for the delayed cohort was 91% (129/142). 63% returned to competition sport after 12-months, at an average return time of 14 months. Few patients (n=10) returned before 9 months. In the delayed group 33% had a subsequent ACL injury. This was not reduced when compared to the non-delayed group (31% rate) in which a majority (58%) returned to competition sport before 12 months. Subsequent ACL injury rates were also highly similar when patients who returned before 12 months postoperatively were compared with those who returned after 12 months (33% vs. 32%, respectively). The main difference between the groups was in the timing of graft ruptures which occurred at a mean 32 months in the delayed group which was significantly greater compared to 18 months in the non-delayed group (p=0.001).

Conclusion

While a majority of younger patients observed specific advice to delay their return to competition sport, a third still returned before the recommended time. For those who did wait until at least 12 months before resuming play, the overall rates of subsequent ACL injury were high at mid-term follow-up, with a third sustaining further injury. Continued effort needs to be placed on reducing the high reinjury rate in younger athletes and alternative approaches for this should be explored.