Magnetic resonance imaging of the Lisfranc ligament of the foot.

Early recognition of subtle Lisfranc injuries is important, because deformity and disability may develop after initially unremarkable radiographs. The authors studied 23 patients (mean age, 25.4 years) with a history of midfoot trauma with both radiographs and magnetic resonance imaging (MRI). When compared with the uninjured side, diastasis on radiographs ranged from 0 to 2 mm. The MRI revealed 2 intact ligaments, 3 complete tears, and 18 partial tears. All patients with complete tears had at least 2 mm more displacement between the second metatarsal and medial cuneiform, compared with the unaffected side. Because of the presence of complete or near complete rupture, seven patients underwent surgery, and the degree of rupture was confirmed. MRI of five cadaver specimens was also performed, disclosing discrete dorsal and plantar components. MRI was found to be useful in identifying Lisfranc ligament tears. If there is clear diastasis on weightbearing radiographs, MRI is not indicated. Whereas radiographic findings may be equivocal, however, MRI may accurately disclose the degree of ligament disruption.

Labral injuries: accuracy of detection with unenhanced MR imaging of the shoulder.

PURPOSE: To prospectively assess the accuracy of unenhanced magnetic resonance (MR) imaging in the detection and localization of labral injuries. MATERIALS AND METHODS: One hundred three patients with clinically suspected shoulder injuries were prospectively examined with unenhanced MR imaging. A combination of gradient-echo and high-resolution fast-spin-echo axial pulse sequences were used. Surgical correlation was obtained in all patients. RESULTS: At surgery, 37 torn anterior, 36 torn superior, and 19 torn posterior labral were identified. The sensitivity for detection of these tears with MR imaging was 100%, 86%, and 74%, respectively; the specificity was 95%, 100%, and 95%, respectively. Overall, unenhanced MR imaging was 95% accurate in the detection of labral injuries. CONCLUSION: With appropriate pulse sequences, unenhanced MR imaging of the shoulder is an accurate technique for the detection and localization of labral injuries.

Imaging of shoulder instability.

Multiple imaging modalities are used in the evaluation of the patient with known or suspected instability. Plain films are often the initial study and are useful in detecting fractures and assessing alignment. Magnetic resonance imaging, with its multiplanar capabilities, such as that of visualizing soft-tissue structures, is rapidly becoming the study of choice for shoulder instability. Ultrasonography and computed tomography arthrography have limited roles in the evaluation of the patient with instability.