Skeletally Immature Patients With Classic Anterior Cruciate Ligament Bone Bruise Patterns Have a Higher Likelihood of Having an Intact Anterior Cruciate Ligament Compared With Skeletally Mature Patients.

BACKGROUND: The incidence of anterior cruciate ligament (ACL) tears in skeletally immature patients with an ACL bone contusion pattern has been sparsely investigated. The purpose of this study is to investigate whether physeal status has an influence on the likelihood of sustaining an ACL tear when classic bipolar ACL bone bruising pattern is present. METHODS: Magnetic resonance imaging reports were queried for "contusion" on all patients between 6 and 22 years between 2015 and 2019. Images were reviewed to denote all intra-articular pathology and the physeal status of the femur and tibia. The primary outcome was the incidence of ACL tears in patients with the presence of bipolar bone contusions. Fischer exact testing was used to determine associations. RESULTS: Of 499 patients included, 269 of those had bipolar bone contusions. Patients with bipolar bone contusions and ACL tears had a shorter duration between injury and imaging date compared with patients with ACL tears without bipolar bone contusions (6.9 vs. 38.6 d, P =0.05). Patients with an open femoral physis had a higher likelihood of having an intact ACL despite the presence of bipolar bone contusions than patients with a closed femoral physis (10.8% vs. 1.0%, P <0.001). Of patients with bipolar bone contusions, those with an intact ACL were younger than patients with an ACL tear (14.6 vs. 16.4, P =0.017). CONCLUSIONS: Although bipolar bone contusions of the central lateral femoral condyle and posterior lateral tibial plateau are typically found after ACL injury, these bipolar contusions can be found concomitantly with an intact ACL and were more often found in relatively younger patients. Patients who have an open femoral physis have a higher likelihood to have an intact ACL despite the presence of bipolar bone contusions compared with patients who have a closed femoral physis. LEVEL OF EVIDENCE: Level IV-cross-sectional.

The Incidence of Posterolateral Tibial Plateau and Central Lateral Femoral Condylar Impaction Fractures in a Pediatric and Young Adult Population.

BACKGROUND: Posterolateral tibial plateau and central lateral femoral condylar impaction fractures are known to occur in the setting of anterior cruciate ligament (ACL) tears. There have been no prior investigations into the incidence and morphology of posterolateral tibial plateau impaction fractures in the setting of ACL injury in a pediatric population. METHODS: Patients between 9 and 22 years of age with knee magnetic resonance imagings (MRIs) performed demonstrating complete or partial ACL tear were included in this study. MRI reports were reviewed to denote the presence of posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament injury, meniscus tears, cartilage lesions. MRIs were reviewed by 2 fellowship-trained orthopaedic surgeons to denote the presence of posterolateral tibial plateau and central lateral femoral condylar impaction fractures and physeal status of femoral and tibial physes. Statistical analysis performed included χ 2 analysis and the Student t testing. RESULTS: A total of 328 patients with a primary ACL tear were identified. The mean age of patients included was 16.5 years (range: 9.0-21.5). The incidence of posterolateral tibial plateau impaction fractures was 83/328 (25.3%) while the incidence of lateral femoral condylar impaction fractures was 119/328 (36.3%). Bipolar impaction fractures occurred in 37/328 (11.3%). Of the 83 tibial impaction fractures identified, 82 were low-grade morphologic subtypes. Patients with lateral tibial plateau impaction fractures were older than those with no fracture (17.2±2.2 vs. 16.3±2.1, P =0.001). Only 3/38 (7.9%) patients with an open tibial physis sustained a tibial plateau impaction fracture compared with 80/290 (27.6%) with a closed tibial physis (χ 2 value: 6.9, P =0.009). There was no difference in proportion of patients with lateral femoral condylar impaction fractures based on femoral physeal status ( P =0.484). CONCLUSION: The incidence of posterolateral tibial plateau impaction fractures in the setting of ACL tear in a pediatric and young adult patient population appears to be lower while lateral femoral condylar impaction fractures occur more frequently when comparing to previously reported incidences found in adult populations in the literature. Furthermore, posterolateral tibial plateau impaction fractures occur less frequently in those with an open proximal tibial physis and high-grade posterolateral tibial plateau bone loss is exceedingly rare in pediatric and young adult patients. Lateral femoral condylar impaction fractures are associated with lateral meniscal tears and medial meniscal ramp lesions. LEVEL OF EVIDENCE: Level IV-cross-sectional study.