[Hypermobile snapping medial meniscus: features on flexion-extension MRI].

We report 3 cases of snapping medial meniscus due to hypermobility confirmed on extension and flexion MR imaging. The anterior horn of the medial meniscus was anteriorly subluxed during extension with reduction during flexion. Analysis of our imaging data and a review of the literature confirm that this relates to hypermobile medial meniscus, an anatomical variant.