MR imaging of meniscal malformations of the knee mimicking displaced bucket-handle tear.

We report two cases of patients with lateral meniscal malformations of the knee that were found incidentally. Magnetic resonance imaging (MRI) of both cases showed a fragment-like meniscus structure located in the intercondylar notch, very similar to the "fragment in the intercondylar notch sign" observed in displaced bucket-handle tear. Arthroscopic examinations revealed a ring-shaped lateral meniscus in one case, and "flipped-over" lateral meniscus in the other. In the latter, a similar lateral meniscal malformation was observed contralaterally at MR arthrography.