Scot E. Campbell, MD
US Air Force Wilford Hall Medical Center, 2200 Bergquist Drive Suite 1, Lackland AFB, TX 78236, USA
Ankle injuries are estimated to constitute as many as 21% of sports-related injuries . Both intra-articular and extra-articular injuries may be present, commonly with multiple concurrent injuries . The clinical manifestations of many injuries may be subtle  or may overlap with other injuries . Although plain film radiography has traditionally been the most common modality to image the ankle, MRI has taken a much more prominent role in recent years because of superior soft tissue resolution and the ability to noninvasively visualize the osseous structures, cartilage, and soft tissues of the ankle. In this review, we discuss the pertinent anatomy and common pathology seen in sports-related ankle injuries.
Magnetic resonance imaging techniques for the ankle vary between institutions. We employ a sagittal inversion recovery sequence, which provides homogeneous fat suppression over the curved ankle joint. Additionally, we use an intermediate echo-time, fast-spin-echo proton density technique for cartilage-sensitive imaging in three planes .
Osteochondral lesions of the talar dome are usually posttraumatic in origin , and can be a source of continued pain, recurrent synovitis, or intra-articular bodies . Modified versions of the grading system described by Clanton and DeLee  have been used to describe the appearance of osteochondral talar dome lesions at MR arthrography . More recently, a 5-point grading system has been used with noninvasive, high-resolution MRI to evaluate the articular cartilage of the talar dome . This describes grade 0 as normal cartilage, grade 1 as signal abnormality without defect, grade 2 as fibrillation or fissures not extending to bone (Fig. 1), grade 3 as cartilage flap or bone exposed (Fig. 2), grade 4 as loose undisplaced fragment (Fig. 3), and grade 5 as a displaced fragment . With appropriate techniques, MRI is accurate in grading talar dome osteochondral lesions according to this scale . A variety of
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