MRI and Surgical Findings in Deltoid Ligament Tears

OBJECTIVE. The objectives of our study were to determine the accuracy of new MRI criteria in detecting tears of the superficial deltoid ligament of the ankle, the accuracy of established criteria for detecting deep deltoid ligament tears, the most common location of superficial deltoid ligament tears, and the frequency of other injuries associated with deltoid tears. MATERIALS AND METHODS. A chart review yielded 89 cases over a 3-year interval in which ankle MRI was followed by open or arthroscopic surgery and the surgical report described findings in the deltoid ligament. One case was excluded because the MRI study was technically inadequate. MRI and surgical reports were then compared for the presence and location of deltoid ligament tears. RESULTS. MRI findings of focal detachment of the superficial deltoid origin or detachment of the fascial sleeve of the medial malleolus yielded a sensitivity for superficial deltoid ligament tears of 83.3% (45/54) and specificity of 93.9% (31/33). Eight of nine prospectively missed tears were visible on retrospective review. All superficial deltoid tears involved the origin of the ligament from the medial malleolus, and six involved mid or distal bundles of the superficial deltoid as well. MRI findings of discontinuity or nonvisualization of discrete fibers yielded a sensitivity for deep deltoid ligament tears of 96.3% (26/27) and specificity of 97.9% (46/47). CONCLUSION. MRI has a high accuracy for deltoid ligament tears in consecutive cases prospectively evaluated by musculoskeletal radiologists. The location of superficial deltoid ligament tears differed in our series from findings previously reported in the imaging literature.