Abstract
Background:
Prior research has shown distinct bone edema patterns on knee MRI after contact and non-contact ACL ruptures, suggesting that injury pathomechanics differ between these two injury mechanisms. However, it is unclear whether there are epidemiological differences between adolescents with contact versus non-contact ACL ruptures.
Hypothesis:
It was hypothesized that adolescents with non-contact ACL ruptures (compared to those with contact ACL ruptures) would be older and more often skeletally mature. We also expected that concomitant soft tissue injuries (meniscus tear and other ligament injury) would be more common in the contact injury cohort.
Methods:
Adolescents treated at a tertiary care children’s hospital system for ACL rupture from 2016-2024 were retrospectively reviewed. Inclusion criteria included ACL rupture requiring reconstruction, age 10 to <20 years, and available MRI of the injured knee. Exclusion criteria included congenital absence of ACL and incomplete imaging. Skeletal maturity was determined by the tibial and femoral physeal status on MRI (open=both open, transitional=at least one partially closed, closed=either closed). The mechanism of injury was recorded from patient notes and defined as follows: non-contact injury=no forcible blow to the injured knee; contact=direct, forcible blow to the knee at the time of injury. Demographic, radiologic, and clinical variables were compared between the two cohorts (contact and non-contact).
Results:
756 patients were included (66.0% non-contact, 48.7% female, median age 15.5 years). In the non-contact cohort, female sex and sports-related injuries were more common than in the contact cohort (p=0.009 and p<0.001, respectively). Non-contact patients tended to be older chronologically (p=0.005) and skeletally mature (p=0.002) (Table 1). Rates of meniscus injury and concomitant ligament injury were similar between the groups (p >0.05). Considering only the 685 patients with sport-related injuries, the distribution of sport at the time of injury varied significantly (p<0.001), with American football being more common in the contact cohort (25.4% vs 17.3%, p=0.015). Contact injuries were also more commonly sustained during official game play (78.5% vs 58.5% p<0.001).
Conclusion:
There are clear epidemiological differences in adolescents who sustain non-contact and contact ACL ruptures. In this cohort, non-contact patients tended to be older, female, and injured during sport participation, whereas contact injuries had a higher rate of non-sport injuries. However, rates of concomitant soft tissue injuries seem to be similar between the groups.
