16-year-old female history of right patellar dislocation. MENISCI: No significant abnormality noted.ARTICULAR CARTILAGE AND BONE: There is edema within the anterolateral aspect of the lateral femoral condyle as well as the medial aspect of the patella indicating contusions from a recent transient lateral patellar dislocation. There is a small rounded focus of low signal intensity along the medial aspect of the patella, which may represent a small avulsion fracture, but this is equivocal. The femoral trochlea is shallow indicating dysplasia. The articular cartilage of the lateral facet of the patella appears normal. There appears to be blistering of the articular cartilage of the far lateral aspect of the femoral trochlea. The tibiofemoral articular cartilage appears intact.LIGAMENTS: Cruciate ligaments are intact. Edema along the superior band of the MCL could represent a sprain but the ligament itself otherwise appears normal. The LCL is intact. There is thickening and increased signal intensity of the medial retinaculum and neither attachment of the medial patellofemoral ligament is clearly visualized indicating a tear. EXTENSOR MECHANISM: The quadriceps and patellar tendons are intact. The TTTG distance is 17-18 mm which is borderline abnormal.ADDITIONAL
Imaging findings of recent patellar dislocation as described above with femoral trochlea dysplasia, borderline elevated TTTG, and tearing of the medial patellofemoral ligament. Although we see no loose bodies within the joint, there is a lipohemarthrosis and a possible small avulsion fracture from the medial aspect of the patella.