41-year-old male with right knee pain. MENISCI: Curvilinear signal abnormality in the posterior horn of the medial meniscus, extending to the tibial articular surface, on one or perhaps two images, is suspicious for a small undersurface tear. Signal abnormality extending into the body of the medial meniscus likely represents intrasubstance degeneration. The anterior horn of the medial meniscus appears normal. The body of the lateral meniscus appears slightly prominent, perhaps representing a mild discoid morphology. We see no lateral meniscal tear.ARTICULAR CARTILAGE AND BONE: There is edema within the posterior aspect of the medial tibial plateau. A small focus of curvilinear low signal intensity within the edema in the subchondral bone beneath the peripheral fibers of the posterior horn of the medial meniscus likely represents a small nondisplaced/nondepressed subchondral fracture. Heterogeneity of the articular cartilage of the inferior aspect of the medial femoral trochlea, with a focus of low signal intensity in the underlying subchondral bone, likely represents focal degeneration. The articular cartilage of the patella and lateral compartment are intact.LIGAMENTS: Although the distal fibers of the anterior collateral ligament appear taut, the proximal fibers are poorly defined. Furthermore, there is abnormal signal intensity along the lateral aspect of the ligament, that we suspect represents torn fibers. These findings suggest at least a full-thickness tear of the posterolateral bundle of the ACL, and probably a tear through the entirety of the ligament proximally. The posterior collateral ligament is within normal limits. There is mild edema superficial to the medial collateral ligament, which may represent a mild sprain, but the ligament itself appears normal. The lateral collateral ligament complex is intact.EXTENSOR MECHANISM: The extensor mechanism is intact.ADDITIONAL
1. Findings are compatible with a small nondisplaced/nondepressed subchondral fracture in the far posterior aspect of the medial tibial plateau, with a small undersurface tear of the overlying posterior horn of the medial meniscus.2. Findings suggestive of at least a full-thickness tear of the posterolateral bundle of the anterior collateral ligament, and probably a full-thickness tear through the entire ligament proximally.