Medial meniscocapsular separation: MR imaging criteria and diagnostic pitfalls.

Various magnetic resonance imaging (MRI) signs can be used in the diagnosis of medial meniscocapsular separation. A thorough knowledge of the normal anatomy of the medial meniscocapsular junction is essential to understand these signs. MRI signs used in the diagnosis of meniscocapsular separation include meniscal displacement relative to the tibia, meniscal corner tear, perimeniscal fluid, irregular meniscal outline, meniscofemoral and meniscotibial extension tears, and interposition of contrast medium between the meniscus and the MCL. Potential causes of false positive diagnosis of meniscocapsular separation include MCL bursitis, meniscal cyst, MCL tear, joint effusion, and perimeniscal fat.