The clinical utility and diagnostic performance of MRI for identification and classification of knee osteochondritis dissecans.

Osteochondritis dissecans of the knee, a lesion of the subchondral bone that may involve partial or total separation of a fragment of the articular cartilage and the subchondral bone from the articular surface, is an increasingly recognized cause of knee pain and joint dysfunction. Individuals with unresolved osteochondritis dissecans lesions often progress to osteoarthritis and often have poor long-term outcomes1-4. Osteochondritis dissecans presents in skeletally immature children and adolescents (juvenile form) or in skeletally mature adults (adult form)5,6. Management and potential healing of osteochondritis dissecans lesions of the knee are highly variable, depending on the skeletal maturity of the individual and the size, location, and stability of the defect7-9. Juvenile cases that involve small and stable lesions have the greatest potential for healing with nonoperative management9. In contrast, unstable osteochondritis dissecans lesions and lesions in skeletally mature individuals often fail to respond to nonoperative measures and require operative intervention to alleviate symptoms7,9. Early identification and accurate staging of the severity of the osteochondritis dissecans lesion are likely critical to treatment success since they may lead to early intervention and prevention of further articular cartilage degradation. There is a great need for noninvasive clinical tools that can diagnose and grade the severity of osteochondritis dissecans lesions of the knee, monitor disease progression, and assess clinical outcomes of treatments for osteochondritis dissecans. Although both radiography and magnetic resonance imaging (MRI) are routinely used to identify and evaluate osteochondritis dissecans lesions of the knee, MRI is often the imaging modality of choice and has been recommended as a technique to follow the healing response and degree of revascularization of the lesion6,7. Despite the widespread use of MRI as a clinical tool to diagnose and monitor the progression or resolution of osteochondritis dissecans lesions of the knee, to our knowledge, no systematic reviews on MRI diagnosis and grading of osteochondritis dissecans lesions of the knee that identify the sensitivity, specificity, accuracy, and reliability of MRI compared with arthroscopy are available in the literature. Without a comprehensive understanding of the diagnostic utility of MRI to characterize the severity of structural articular cartilage and subchondral changes associated with osteochondritis dissecans, insight into its use as a noninvasive and evidence-based tool to guide diagnostic and treatment practices remains limited. The purpose of this study was to systematically review the literature relative to the following questions: (1) Is MRI a valid, sensitive, specific, accurate, and reliable imaging modality to identify osteochondritis dissecans of the knee compared with arthroscopy? (2) Is MRI a sensitive tool that can be used to characterize disease severity and stability of osteochondritis dissecans lesions of the knee? The aims of this systematic review are to summarize relevant data and identify strengths and weaknesses in the literature. The results of the systematic review are discussed relative to the implications for the clinical utility of MRI as a tool to identify and classify the severity and stability of osteochondritis dissecans of the knee.