50-year-old man with pain and locking of left knee. Evaluate for torn meniscus. MENISCI: There is globular signal within the medial meniscus indicating intrasubstance degeneration, but we see no frank tear. There is also globular signal within the lateral meniscus indicating intrasubstance degeneration, without a discrete tear. There is slight prominence of the body of the lateral meniscus, which may reflect a mild discoid morphology. ARTICULAR CARTILAGE AND BONE: There is a focal near-full-thickness to full-thickness defect involving the articular cartilage of the weightbearing portion of the medial femoral condyle, which measures approximately 1.5cm in AP dimension. There is perhaps mild fraying of the articular cartilage of the medial tibial plateau. The articular cartilage of the lateral tibiofemoral joint appears relatively intact. There is moderate to severe degeneration of the articular cartilage of the trochlea, particularly inferiorly, with multiple subchondral cysts. There is superficial degeneration of the articular cartilage of the patella. LIGAMENTS: The cruciate and collateral ligaments appear intact. EXTENSOR MECHANISM: The extensor mechanism appears intact.ADDITIONAL
1.Osteoarthritis, most severely affecting the femoral trochlea, with a loose osteochondral fragment within the joint posteriorly, which may be the source of the patient’s joint locking.2.Joint effusion with edema extending inferiorly from the Baker’s cyst which may reflect edema or recent rupture. 