Straight Form of Calcaneofibular Ligament as a Three-Dimensional Magnetic Resonance Imaging Sign in Diagnosis of Calcaneofibular Ligament and Anterior Talofibular Ligament Inferior Fascicle Injury.

The present study was performed to investigate the morphological characteristics of the calcaneofibular ligament (CFL) and evaluate its relationship to the anterior talofibular ligament (ATFL) in patients with lateral ankle ligament injury using 3-dimensional magnetic resonance imaging (3D-MRI). This retrospective study involved 35 patients with lateral ankle ligament injury and 24 patients without a history of ankle trauma and a bone abnormality as controls. Reconstructed 3D-MRI was used to classify the form of the CFL as curved, wavy, or straight. The presence/absence of continuity between the fibula and CFL was evaluated in the 35 patients with injury, who were divided into 2 groups (continuity and discontinuity groups). The number of fascicles in the ATFL and the continuity between the distal end of the fibula and the proximal end of the ATFL were then evaluated. Among the patients with injury, 54.3% had the curve type of CFL, 34.3% had the wave type, and 11.4% had the straight type. In the control group, 62.5% had the curve type, 37.5% had the wave type, and none had the straight type. Continuity between the fibula and CFL was seen in 88.6%, and discontinuity was seen in 11.4%. Additionally, 85.7% had double fascicles in the ATFL. Inferior fascicle discontinuity between the ATFL and fibula was found in 13.3% with a double-fascicle ATFL; in all of these patients, the form of the CFL was straight and exhibited inferior fascicle discontinuity. The straight form of CFL could be a 3D-MRI sign in the diagnosis of CFL and ATFL inferior fascicle injury.