MRI Criteria for Ramp Lesions of the Knee in Children with Anterior Cruciate Ligament Tears.

OBJECTIVE: The purpose of this study was to investigate the performance of MRI criteria for identifying meniscal ramp lesions in children with concomitant anterior cruciate ligament (ACL) tear using arthroscopy as the reference standard. METHODS & MATERIALS: This IRB-approved, HIPAA-compliant retrospective study included 85 children who had a pre-operative MRI and underwent arthroscopically-guided primary ACL reconstruction between February 1, 2017 and December 31, 2019. Blinded to arthroscopic findings, two radiologists reviewed all MRI examinations and reached consensus on the presence or absence of an effusion and various findings within the medial and lateral tibiofemoral joints. Chi-squared, Fisher's exact, Independent T, and Mann-Whitney U tests were used to compare MRI findings between patients with and without arthroscopically-confirmed meniscal ramp. RESULTS: At arthroscopy, 35 children (23 boys and 12 girls, 15.7 ± 2.0 years) had ramp lesions and 50 children (22 boys and 28 girls, 15.1 + 2.4 years) had intact meniscocapsular junctions. Knees noted to have a ramp lesion were significantly more likely to have MRI findings of a medial meniscus tear (p=0.005), peripheral meniscal irregularity (p=0.001), junctional T2-weighted signal (p<0.001), and meniscocapsular ligament tear (p<0.001). No significant difference was found between ramp and non-ramp groups for the presence of an effusion (p=0.653), lateral meniscus tear (p=0.081), or extent of tibial plateau marrow edema (medial, p=0.666; lateral, p=0.829). CONCLUSION: MRI findings associated with arthroscopic diagnosis of meniscal ramp lesion include medial meniscus tear, peripheral meniscal irregularity, junctional fluid-like signal, and capsular ligament tear.