16 year-old male. Pain, instability. Evaluate for ACL tear. MENISCI: The lateral and medial menisci are normal in signal intensity and morphology without evidence of a tear.ARTICULAR CARTILAGE AND BONE: ACL osseus avulsion fracture of the medial tibial tubercle with surrounding edema type signal in the intercondylar eminence extending into the medial and lateral tibial plateau consistent with bone contusion.Small impaction fracture of the subchondral bone in the lateral femoral condyle with an articular cortical step-off of 3 mm (series 701, image 23). There is adjacent edema type signal in the lateral femoral condyle consistent with bone contusion. Tibiofemoral and patellofemoral compartment cartilage is intact.LIGAMENTS: The ACL is completely avulsed from its tibial insertion with a small attached bone fragment comprised of the medial tibial tubercle. Mild retraction of the ACL, which is diffusely high in signal. High PCL, MCL, and LCL are intact.EXTENSOR MECHANISM: No significant abnormality noted.ADDITIONAL
1. ACL avulsion fracture from the tibial intercondylar eminence.2. Small impaction fracture of the lateral femoral condyle with a 3 mm articular step-off.3. Bone contusions in the tibial intercondylar eminence extending into the medial and lateral tibial plateau. 