Poster 326: Concomitant Meniscal and Ligamentous Injuries Associated with Pediatric and Adolescent ACL Tears: Data from the Boston Children’s Hospital ACL Registry

OBJECTIVES: There has been a well-documented increase in pediatric and adolescent ACL injuries and surgery in recent years, especially in athletes. ACL tears are infrequently isolated injuries, as there are known associated concomitant injuries. However, the risk factors for and incidence of these different associated injuries are poorly characterized, particularly in this high-risk population. Therefore, the purpose of this study was to use a large database of pediatric and adolescent ACL surgeries to examine the incidence of common concomitant soft tissue injuries and their associated risk factors in this sub- population. METHODS: Following institutional review board approval, a natural language processing (NLP) pipeline was developed to identify ACL surgery cases from the electronic health records of patient evaluated at Boston Children’s Hospital Orthopedics and Sports Medicine clinics between 2000-2020 (from >23 million notes). Following training and validation, the model achieved median accuracy of 98%, median sensitivity 97% and median specificity of 98% in identifying ACL surgery cases and extracting variables from clinical visits and operative notes. Stepwise logistic regression was performed to evaluate the associations between sex, age, body mass index (BMI), injury mechanism (contact vs. non-contact injury), and history of prior ipsilateral ACL injury with presence of concomitant injuries to the meniscus (lateral, medial, or both), medial collateral ligament (MCL), posterior cruciate ligament (PCL) and posterolateral corner (PLC), which was defined as any grade 2 or 3 fibular/lateral collateral ligament, popliteofibular ligament, or popliteus tendon injury. Adjusted odds ratios (aOR) and corresponding 95% confidence interval (95%CI) were calculated and considered significant at P<.05. RESULTS: The model identified 5,648 ACL surgeries from 4,992 unique patients of any age (age: 17.0 ± 4.0; 53% females), of which 4,727 surgeries (4,221 unique patients, age: 15.9 ± 2.2; 55% females) were performed in children and adolescents (<20 years old). Of these cases in the study population, 2,895 (61%) demonstrated at least one concomitant soft-tissue injury. These concomitant injuries included 1,715 (36%) medial meniscus injuries, 1,632 (35%) lateral meniscus injuries, 1,274 (27%) MCL injuries, 312 (7%) PCL injuries, and 445 (9%) PLC injuries. For meniscal injury, higher BMI (aOR=1.03 [95%CI: 1.01, 1.04]) and older age (aOR=1.12 [95%CI: 1.09, 1.15]) were associated with increased rate of concomitant medial meniscus injuries (P<.001). Similarly, higher BMI (aOR=1.02 [95%CI: 1.00, 1.03]), older age (aOR=1.09 [95%CI: 1.06, 1.12]), and history of prior ipsilateral ACL injury (aOR=1.39 [95%CI: 1.10, 1.76]) were associated with increased rate of concomitant lateral meniscus injury, while female sex (aOR=0.79 [95%CI: 0.70, 0.90]) was associated with decreased rate of concomitant lateral meniscus injuries (P<.01). Female sex (aOR=1.31 [95%CI: 1.14, 1.51]), older age (aOR=1.17 [95%CI: 1.14, 1.21]), and contact injury (aOR=1.59 [95%CI: 1.36, 1.85]) were associated with increased rate of concomitant MCL injury. History of prior ipsilateral ACL injury (aOR=0.68 [95%CI: 0.52, 0.89]) was associated with decreased rate of concomitant MCL injury (P<.01). Older age (aOR=1.06 [95%CI: 1.01, 1.12]) was associated with increased rate of concomitant PCL injury, while female sex (aOR=0.63 [95%CI: 0.49, 0.79]) was associated with decreased rate of concomitant PCL injury (P<.03). Finally, older age (aOR=1.21 [95%CI: 1.15, 1.27]) and contact injury (aOR=1.37 [95%CI: 1.10, 1.69]) were associated with increased rate of concomitant PLC injury, whereas history of prior ipsilateral ACL injury (aOR=0.46 [95%CI: 0.27, 0.78]) was associated with decreased rate of concomitant PLC injury (P<.01). CONCLUSIONS: The current largescale single-site study of well over 4,000 surgical cases suggests that the majority (61%) of pediatric and adolescent ACL injuries are accompanied with one or more injuries to major soft tissue structures within the knee, with injuries to the medial and lateral menisci being the most prevalent. Notably, this rate is higher than what was previously reported in the pediatric literature, adding additional concerns and complexities to the clinical care of pediatric and adolescent patients with ACL tears. Higher BMI, older age, and a contact injury mechanism showed consistent adverse effects, in terms of concomitant soft tissue injury risk. History of prior ipsilateral ACL injury and female sex had some positive and some negative prognostic value, in terms of soft tissue risk, though to a varying degree. Specifically, older age and higher BMI were associated with increased rates of concomitant meniscal injury, which is in line with current literature. Patient with contact injuries were more likely to have injury to the collateral ligaments. The sex-related differences in injury patterns, as well as the potentially protective effect of prior ipsilateral ACL injury on collateral ligaments suggest potentially lower energy injury mechanisms being associated with ACL graft tear, compared with native ACL ligament tear. Given the implications of concomitant soft tissue injuries on overall prognosis and arthritis risk in this young, active sub-population, these data underscore the importance of future studies investigating prevention strategies and awareness and the vigilance ACL surgeons must apply to the detection and thoughtful treatment of these common additional injuries.