Juvenile versus Adult Osteochondritis Dissecans of the Knee: Appropriate MR Imaging Criteria for Instability

PURPOSE: To retrospectively compare the sensitivity and specificity of previously described magnetic resonance (MR) imaging criteria for the detection of instability in patients with juvenile or adult osteochondritis dissecans (OCD) of the knee, with arthroscopic findings as the reference standard. MATERIALS AND METHODS: Informed consent was waived by the Institutional Review Board for this HIPAA-compliant study. The study group consisted of 32 skeletally immature patients (25 boys, seven girls; mean age, 14.4 years) with 36 juvenile OCD lesions of the knee and 33 skeletally mature patients (25 men, eight women; mean age, 26.2 years) with 34 adult OCD lesions of the knee. All patients had been evaluated with MR imaging and arthroscopy. MR studies were retrospectively reviewed by two radiologists in consensus to determine the presence of previously described MR imaging criteria for OCD instability (ie, high T2 signal intensity rim, surrounding cysts, high T2 signal intensity cartilage fracture line, and fluid-filled osteochondral defect). Sensitivity and specificity of the criteria were calculated separately for juvenile and adult OCD lesions. RESULTS: Separately, previously described MR imaging criteria for detection of OCD instability were 0%-88% sensitive and 21%-100% specific for juvenile OCD lesions and 27%-54% sensitive and 100% specific for adult OCD lesions. When used together, the criteria were 100% sensitive and 11% specific for instability in juvenile OCD lesions and 100% sensitive and 100% specific for instability in adult OCD lesions. CONCLUSION: Previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee.