Younger age increases the risk of sustaining multiple concomitant injuries with an ACL rupture

Purpose Anterior cruciate ligament (ACL) tears have a major impact on the individual and society. Long term effects may be mediated by injuries that occur concurrently to the ACL tear. The purpose of this study was to describe in a nationwide cohort the traumatic meniscal injuries and bone marrow lesions concomitant to ACL tears, their age and sex distribution and the rate any association with ACL reconstruction. Methods All ACL tears in Iceland from 2006 to 2011 and their concomitant bone marrow lesions and meniscal injuries were identified from MRI reports. These injuries were further classified by location, sex and age. The cohort was divided into under 17, 17–29, 30–49 and above 50 to reflect likely differences in the mechanisms of injury and risk factors that may vary with age. Data from the Icelandic Social Insurance Administration were used identify all those who were operated. Descriptive analysis was performed to show the proportion of ACL injured knees sustaining concomitant injuries and how these injuries varied with age, sex, and subsequent treatment Results 1365 knees with ACL ruptures were included. Only 13% of knees had no concomitant injury identified. Overall, 57% of knees had a bone marrow lesion in at least one location and 70% of knees had at least one traumatic meniscal injury. A greater number of combined lateral tibial and femoral bone marrow lesion was seen in younger age groups ( χ 2 (3) = 113.32, p < 0.0001). Bruises in the medial compartment were the least common concomitant injuries. More injuries were related to higher chances of ACL reconstruction (OR 1.6, 95% CI 1.4–1.7). Age was associated with risk of all injury types and locations with older age generally being associated with fewer injuries. Conclusion In an ACL ruptured cohort, the overall incidence of BMLs may be lower and meniscus injuries higher than previously reported. However, these injuries are more prevalent in the younger cohort potentially resulting in a poorer long-term prognosis. Knowledge of the association between age and concomitant injuries will help guide rehabilitation. Level of evidence II.