16 year old girl with history of left knee osteochondral defect and intra-articular loose body, presenting with continued left knee pain. MENISCI: There is marked attenuation of the anterior horn and body of the lateral meniscus. As the previous study showed a discoid lateral meniscus, the meniscal attenuation seen on the current study likely in part reflects interval surgery. However, there is also obliquely oriented signal extending through the junction of the body and posterior horn, compatible with a tear, and we suspect that the attenuation of the remainder of the body of the lateral meniscus as well as the anterior horn also in part reflects chronic attritional tearing. Blunting of the free edge of the posterior horn of the lateral meniscus may also represent prior surgery. There is a cyst along the posterior horn of the medial meniscus that appears to arise from its peripheral fibers. Horizontally oriented linear signal within the posterior body of the medial meniscus extending to the femoral articular surface seen on a single MRI slice may represent a horizontal tear. ARTICULAR CARTILAGE AND BONE: Cortically-based intramedullary low signal intensity within the distal femoral metaphysis posteriorly likely represents a healed nonossifying fibroma. As seen on prior radiographs, there is an osteochondral defect of the weightbearing portion of the lateral femoral condyle with heterogeneity of the overlying cartilage. The osteochondral defect measures approximately 1.4cm in greatest dimension. There is an ovoid loose body situated anterior to the lateral meniscus, which measures just over 1cm in greatest dimension. The articular cartilage of the medial tibiofemoral compartment appears normal, as does that of the patellofemoral compartment. LIGAMENTS: Anterior and posterior cruciate ligaments are intact. Medial collateral ligament and lateral collateral ligament complex are intact. EXTENSOR MECHANISM: Quadriceps tendon and patellar tendon are intact.ADDITIONAL
1.Osteochondral defect of the lateral femoral condyle with intra-articular loose body.2.Lateral meniscal abnormalities described above likely representing a combination of tearing and prior surgery for discoid meniscus.3.Parameniscal cyst that appears to arise from the posterior horn of the medial meniscus, possibly associated with a horizontal tear. 