Magnetic resonance imaging of injury to the lateral ankle ligaments.

To establish the value of magnetic resonance imaging in determining which patients with ankle sprains will benefit from surgical treatment, 1 uninjured volunteer and 15 patients with acute, subacute, and chronic injuries of the lateral ankle ligaments were imaged at 1.0 tesla using a fast imaging with steady-state precision three-dimensional technique and 1.5-mm slice thickness. A dedicated knee coil was used to hold the foot in a neutral or plantar-flexed position. In cases of acute, low-grade injuries, fraying of the anterior talofibular ligaments with intact calcaneofibular ligaments was observed in the presence of edema and hemorrhagic fluid. In cases of acute, high-grade sprains, the calcaneofibular ligament appeared wavy or was visualized only partially or not at all. Subacute injuries showed ligament disruption; chronic lesions, on occasion, showed atrophy of the calcaneofibular ligament but no edema or hemorrhagic fluid. These findings showed a good qualitative correlation with the results of graded stress radiography. Magnetic resonance imaging can definitely determine the ligaments involved in lateral ankle sprains and provide useful anatomic information in cases in which acute or reconstructive surgery is contemplated. However, the magnetic resonance imaging findings do not directly correlate with degree of instability and do not replace those of physical examination or routine radiographic studies.