17-year-old male with left knee pain, evaluate for possible patellar dislocation MENISCI: We see no meniscal tears. Globular increased signal within the posterior horn of the medial meniscus likely represents artifact or perhaps a meniscal contusion.ARTICULAR CARTILAGE AND BONE: Marrow edema is seen within the anterolateral aspect of the lateral femoral condyle. This may reflect prior dislocation, although we see no corresponding kissing contusion in the medial aspect of the patella. There is also edema within the anterior aspect of the lateral tibial plateau with an associated subchondral focus of curvilinear T1 signal intensity which may represent a nondisplaced subchondral fracture. The femoral trochlea is abnormally shallow, indicating dysplasia. The tibial tubercle to trochlear groove distance is 19 mm which is borderline abnormal. The Insalata-Salvati ratio is 1.35 suggesting mild patella alta.LIGAMENTS: The medial and lateral collateral ligament complexes are intact. The ACL and PCL are intact. There is mild edema along the abductor tubercle, and the medial patellofemoral ligament is not well visualized at its femoral attachment, perhaps representing a tear.EXTENSOR MECHANISM: The extensor mechanism is intact. ADDITIONAL
1.Edema within the anterolateral femoral condyle suggests prior lateral dislocation of the patella. Although we see no edema within the medial patella, there is edema along the abductor tubercle and incomplete visualization of the medial patellofemoral ligament at its femoral attachment as well as morphologic abnormalities which may predispose to patellofemoral instability as described above.2.Additional edema as well as a probable nondisplaced subchondral fracture along the anterior tibial plateau suggesting a hyperextension/valgus component to the mechanism of injury.