16-year-old male. Lateral pain. Evaluate for lateral meniscus tear. MENISCI: Horizontal signal abnormality predominately within the posterior horn and body of the lateral meniscus extending to the free edge of the meniscus and the femoral articular surface indicating a horizontal tear. There is small intrameniscal cyst formation particularly within the periphery of the posterior horn and the contents of the tear also decompress laterally into a multiloculated para-meniscal cyst located between the lateral capsular structures and the meniscal body. This cyst measures approximately 2 cm in AP dimension, 1.5 cm in CC dimension, and 5 mm in mediolateral dimension with adjacent edema type signal. The body of the lateral meniscus itself appears slightly prominent, suggesting a partial discoid morphology. The medial meniscus is intact.ARTICULAR CARTILAGE AND BONE: Bone marrow signal intensity is normal without evidence of contusion. The tibiofemoral and patellofemoral compartment cartilage is intact with no focal defect.LIGAMENTS: The cruciate and collateral ligaments are intact.EXTENSOR MECHANISM: The extensor mechanism is intact.ADDITIONAL
1. Horizontal tear of the lateral meniscus with para-meniscal cyst formation, as described above. Prominence of the body of the lateral meniscus suggests a partial discoid morphology.2. Approximately 1 cm disc shaped focus of intermediate to low signal intensity within the patellofemoral joint, as described above, may simply represent a peculiar synovial fold/plica but we cannot entirely exclude the possibility of a loose cartilaginous fragment. We see no cartilage defects.