JOURNAL CLUB: MRI Evaluation of Midtarsal (Chopart) Sprain in the Setting of Acute Ankle Injury

Abstract

Midtarsal sprains are commonly associated with acute ankle injury and with ankle sprains. Presently, midtarsal sprains may be underrecognized by radiologists; thus, greater familiarity with the MRI spectrum of ligamentous and osseous injuries at the Chopart joint is important for accurate diagnosis and clinical management.

Normal Anatomy and Traumatic Injury of the Midtarsal (Chopart) Joint Complex: An Imaging Primer

“…included in standard ankle MRI fields of view and does not require a special protocol, such as a midfoot protocol, although the latter can also depict injuries at the joint. Optimal evaluation of the normal midtarsal ligaments is achieved with T1-weighted or proton-density-weighted (PD) images, in either the axial, sagittal, or less commonly coronal plane, on which the ligaments appear as linear low-signal-intensity structures, often surrounded by normal hyperintense periligamentous fat (5,23,24).…”

“…The normal calcaneonavicular component of the bifurcate ligament is nearly always seen on sagittal T1-weighted or non-fat-suppressed PD images as a thin low-signal-intensity structure, surrounded by fat, extending from the anterior process of the calcaneus. The navicular insertion is rarely seen owing to the obliquity of the ligament relative to the sagittal plane ( Fig 4d) (5,24).…”

“…It forms the lateral arm of the Y-shaped bifurcate ligament (3). This ligament is typically visualized, outlined by fat, on sagittal T1-weighted or PD images, arising just lateral to the calcaneonavicular band of the bifurcate ligament (Fig 4e); the dorsal calcaneocuboid ligament and the calcaneocuboid component of the bifurcate ligament may be continuous and thus can be difficult to distinguish from each other (5).…”

“…Midtarsal joint complex trauma can be subdivided into lowenergy midtarsal sprains and the relatively rare high-energy Chopart joint fracture-dislocation. The incidence of midtarsal sprains-the most common Chopart joint injury-varies, ranging up to one-third of patients experiencing ankle inversions (5)(6)(7). Unfortunately, accurate and timely diagnosis of midtarsal sprains may be hindered by lack of familiarity with the entity, its clinical significance, and imaging manifestations.…”

“…Unfortunately, accurate and timely diagnosis of midtarsal sprains may be hindered by lack of familiarity with the entity, its clinical significance, and imaging manifestations. A majority of patients with midtarsal sprains have coincident lateral ankle sprains, a better-known entity for clinicians and radiologists alike (5,8); therefore, midtarsal sprains may often be mistakenly diagnosed as lateral ankle sprains. Delayed diagnosis can lead to prolonged symptoms with the potential for developing instability and eventual osteoarthritis across the Chopart joint.…”