CONCOMITANT POSTEROLATERAL CORNER INJURIES IN SKELETALLY IMMATURE PATIENTS WITH ACUTE ANTERIOR CRUCIATE LIGAMENT INJURIES

Abstract

Background: Missed and/or untreated posterolateral corner (PLC) injuries are a known cause of anterior cruciate ligament (ACL) reconstruction failure in the adult population. Failed ACL reconstruction causes significant morbidity in the skeletally immature pediatric population. There is little literature on the character and potential significance of posterolateral corner injuries in skeletally immature patients. Methods: Magnetic resonance imaging (MRI) studies of the knee performed at a single tertiary care pediatric hospital between 01/01/2010 and 12/31/2015 for patients who underwent an ACL reconstruction were retrospectively reviewed. Demographic variables were obtained via medical record review, and MRI studies were evaluated for PLC (popliteus, fibular collateral ligament (FCL), popliteofibular ligament (PFL), arcuate ligament) injury, as well as ACL, medial collateral ligament (MCL), bone bruise, fracture, and meniscal pathology by an experienced pediatric musculoskeletal radiologist. Results: Fifty-two patients, 65% of whom were male, with a mean age of 13.8 years at injury were analyzed. PLC injuries were found in 28 patients (54%), with 7 patients (14%) having a complete tear of a component of the PLC. MCL injuries were found in 13 patients (25%). Meniscus tears were found in 25 patients (48%); 17 were of the medial meniscus (33%), and 10 were of the lateral meniscus (19%). A Segond fracture was seen in four patients (8%). The most common injury pattern involved the PFL only (9, 32% of patients with PLC injuries). There was no association between sex (p=0.29), Segond fracture (p=0.09), meniscus injury (p=0.93), or MCL injury (p=0.32) with the risk of PLC injury. There was an association between patient age and PLC injury (p=0.02). For each additional year of age, the odds of PLC injury increased by 1.7 times (OR=1.7 (1.1, 2.8)). Patients were an average age of 14.0 years at ACL reconstruction, and 9 patients went on to re-tear. There was no association between PLC injury and ACL graft failure (p=0.72). Conclusions: This study demonstrates the prevalence of PLC injuries in the setting of concomitant ACL injuries in the skeletally immature patient population. Age was found to predict the odds of PLC injury, which was significantly higher in older skeletally immature patients. No other concomitant injury predicted likelihood of PLC injury.