Acute distal rupture of the calcaneus-fibular ligament near the calcaneus insertion: Magnetic resonance imaging for diagnostic value and comparison to surgical findings—a retrospective case series study

Distal rupture of the CFL (calcaneus-fibular ligament) was unique and important, because it is crucial to diagnose this type of injury before surgical intervention. In the present study, we collected several imaging characteristics based on MRI and tried to determine whether those clues can be used to diagnose distal rupture of CFL specifically and sensitively. Several imaging characteristics based on MRI were collected and used to diagnose and determine the location of CFL injury. All these clues on preoperative MRI were verified by operative findings and postoperative roentgenography. The interobserver agreement for the quality of the MRI images had a p value of 0.6 (McNemar test) and a Cohen's kappa of 65.2% (confidence interval, 50.5-79.9%), and the agreement of the two observers was categorized as substantial. The sensitivity and specificity of distal rupture of CFL between two observers were 76.3% and 91.4% and 72.2% and 85.55%, respectively. The sensitivity and specificity of MRI clues were calculated as follows: hyperintense signal changes (86.1%, 38.6%), peroneal sheath fluid (63.9%, 74.7%), wave or laxity of the ligament (80.6%, 51.8%), fluid exudation around the ligament (80.6%, 51.8%), bone marrow edema on the calcaneus insertion (2.8%, 91.6%), avulsion fracture of the calcaneus (0%, 96.4%), incongruency or disruption of the ligament (69.4%, 77.1%), and exudation on the subtalar joint (52.8%, 71.1%). Preoperative MRI scans are a useful tool to diagnose distal injury of the CFL. Level of Clinical Evidence : Level IV