20 year-old female. Right knee injury playing ultimate Frisbee, foot planted, knee shifted, felt a pop. MENISCI: There is a vertical band of increased signal intensity along/within the peripheral fibers of the posterior horn of the medial meniscus, suggestive of a complete longitudinal tear. Although we see no discrete lateral meniscal tear, the popliteomeniscal fascicles are thickened and indistinct, which can be associated with peripheral tears of the posterior horn.ARTICULAR CARTILAGE AND BONE: There is edema within the posterior aspect of the lateral tibial plateau as well as the lateral femoral condyle above the posterior horn of the lateral meniscus indicating bone contusions. There are also smaller foci of edema within the posterior aspect of the medial tibial plateau and along the far medial aspect of the medial femoral condyle, likely representing contusions as well.LIGAMENTS: The ACL is indistinct and of increased signal intensity particularly along its proximal fibers compatible with a full-thickness tear. The PCL is intact. Edema along the MCL suggests a sprain although the ligament itself appears intact. There is also edema along the LCL proper although the ligament itself appears intact.EXTENSOR MECHANISM: The extensor mechanism is intact.ADDITIONAL
1. Full thickness tear of the ACL with associated bone contusions.2. Findings suggestive of a longitudinal tear of the peripheral fibers of the posterior horn of the medial meniscus.3. Although we see no discrete lateral meniscal tear, thickening and poor definition of the popliteomeniscal fascicles can be associated with peripheral tears of the posterior horn of the lateral meniscus.4. Joint effusion and soft tissue edema, as described above.