Imaging findings of flexion type of hangman's fracture; an attempt for a more objective evaluation with newly introduced scoring system

To identify the flexion type of hangman's fracture on imaging studies. 38 cases of hangman's fracture were retrospectively studied and categorized into flexion and non-flexion groups. Plain radiograph, CT and MRI of these patients were evaluated; 13 radiological parameters that might define flexion injuries were measured. The data were statistically analyzed to identify good criteria and to rank them according to their importance in predicting flexion. Seven radiological criteria that have the highest correlation with flexion injury were identified. These are C2-3 lower end-plate angle, C2-3 posterior body angle, interspinous angle, disc disruption (MRI), widening of interspinous distance, disruption of the posterior ligamentous complex (MRI) and angle at the fracture site. Scoring 1 point for each positive criterion, a total score of 4 predicts flexion injury with 100% sensitivity and 96.9% specificity. Score of 5 has 83.3% sensitivity and 100% specificity. Flexion hangman's injury can be diagnosed by the presence of four out of seven radiological criteria in the newly introduced scoring system. The authors believe that this method may help spinal surgeons in their selection of therapeutic strategy. Advances in knowledge: This study introduces fast, simple and more objective imaging criteria for the diagnosis of flexion hangman's injury and separates it from the non-flexion pattern.