MRI of pediatric meniscal retears following primary arthroscopic surgery: diagnostic accuracy and common findings.

objectiveTo assess MRI's diagnostic accuracy for pediatric meniscal retears and to examine how factors from the primary tear and arthroscopy influence retear patterns. MATERIALS AND

methodsPatients who underwent primary arthroscopic meniscal repair or debridement between 2018 and 2024 followed by repeat MRI of the ipsilateral knee for suspected reinjury were included. Data from operative reports, MRI reports, and clinical follow-up were collected to assess the presence and characteristics of retears. MRI images were re-reviewed by two pediatric musculoskeletal radiologists to evaluate meniscal pathology.

results109 suspected meniscal reinjuries were identified among 101 patients (mean age: 16.7 years), with 74 arthroscopically confirmed retears. MRI demonstrated 96% sensitivity and 94% specificity in detecting retears. Retears predominantly involved the posterior horn (54%) and were more likely to be displaced if the primary tear was displaced (54% vs. 33%, p = 0.04). Primary repairs accounted for 70% of retears and 73% of posterior horn retears. Common postoperative MRI findings associated with retears included the presence of displaced meniscal tears and high linear T2 signal within the meniscus repair site. Medial meniscal retears were more common in patients with a ruptured ACL (p = 0.018) on primary arthroscopy, whereas lateral meniscal retears were more common in patients with an intact ACL (p = 0.002) on primary arthroscopy.

conclusionMRI is specific for detecting meniscal retears, but diagnostic challenges remain in nondisplaced tears and in certain regions, such as the posterior horn. Understanding factors that influence meniscal retear patterns may improve postoperative evaluation and management, ultimately improving clinical outcomes.