Line projected along the intercondylar roof on sagittal knee images. It may be used for the evaluation of correct alignment of tibial tunnel after ACL reconstruction or in the assessment of deflected ligament after ACL injuries.

A bone bruise related to ACL injury is commonly caused by osseous impact during pivot-shift rotatory mechanisms in which there is external rotation of the lateral condyle relative to the fixed tibia. Medullary signal becomes high on T2-weighted images due to osseous edema, subcortical microfracture, or hemorrhage (Fig. 1). When anteromedial mechanism is prevalent, the bone bruise is located more frequently in the posteromedial tibial plateau, near the semimembranosus tendon insertion. According to our experience, bone bruising is considered a sign of ACL tear (highly likely near 90 %), except in pediatric or adolescent patients with more elastic ligament.

It is a protruding osseous excrescence located 2–5 mm below the lateral articular margin of the tibia. This should be a sign of a chronic tear of the ACL.

A bucket-handle tear is defined as a longitudinal tear with displacement of the “handle” fragment (Fig. 2) more frequent in MM. Various MR signs were proposed (sensitive but not specific): the absence of bow tie (longitudinal tear breach), a fragment within the intercondylar notch, a double PCL (fragment displaced under the PCL), a double anterior horn or flipped meniscus (anterior fragment displacement), and a disproportionally small posterior horn (the end or the beginning of the longitudinal tear) (Fig. 3). It is relevant suspecting this lesion of the LM if it appears as a fragment located just posterior to the ACL. Mimics of the double PCL sign include a prominent ligament of Humphrey, a meniscomeniscal ligament, and intercondylar osseous bodies (vv 3).