'Relative' Risk of ACL Re-injury

Purpose: Several studies have examined ACL injury history among relatives of patients undergoing ACL reconstruction, but they have primarily analyzed adult populations with variable results. Additionally, few studies have examined concomitant injuries or post-operative outcomes among pediatric patients with a family history of ACL tear. Therefore, the purpose of this study was to identify the proportion of pediatric ACL patients with a first degree relative who had suffered an ACL tear while also examining concomitant meniscal or ligamentous injuries and subsequent complication rates. Methods 1009 patients who underwent ACL reconstruction at an urban tertiary care children's hospital between January 2009 and May 2016 were contacted via email and/or telephone and asked to complete a follow-up survey. Data collected included subsequent complications - including graft rupture, contralateral ACL injury, and meniscus tears - along with information regarding any relatives who had suffered an ACL tear. Patient medical records were reviewed to determine the age of the patient at the time of surgery as well as concomitant meniscus and ligamentous injuries at the time of injury. Results 425 patients who underwent primary ACL reconstruction completed the survey. The mean age at surgery was 15.0 (SD 2.4) years with a mean follow-up time of 4.6 (SD 2.1) years. Patients were stratified into three groups by the number of first degree relatives (parent or sibling) who had an ACL tear history: no relatives, one relative, or more than one relative. 101 respondents (23.8%) reported at least one first degree relative who had previously torn an ACL. 15 (3.5%) had more than one first degree relative with an ACL tear. There were no differences in the age at time of surgery or the number of concomitant meniscus and ligamentous injuries suffered across the three stratified groups. While children with zero or one affected first degree relative had similar rates of graft failure (11.4% and 9.3%, respectively), those with two or more affected first-degree relatives had a significantly higher graft failure rate (40.0%, p=0.003). There were no differences in the number of post-operative contralateral ACL tears (p=0.44) or meniscus tears (p=0.48) across the groups. When these complications were analyzed together as one outcome, patients with more than one affected first-degree relative suffered more combined graft ruptures, contralateral ACL tears, and meniscal tears (53.3%) than patien