| Sumario: | • Atlantoaxial joint displacement indicators could distinguish high-versus low-energy levels of external force applied to the neck. • The lateral atlanto-dental interval firstly applied to analyze the potential injury of atlantoaxial joint caused by different external force. • Anterior atlanto-dental interval showed the higher values in head and neck injury group than those in hanging and strangulation. The aim of the study was to quantify atlantoaxial displacement indicators on postmortem CT and to evaluate their ability to reflect cervical blunt-force scenarios with different energy levels, particularly high- versus low-energy impacts. A total of 182 cases were selected, including six groups based on the death scenario: head and neck injury caused by traffic accident (40), thoracoabdominal injury caused by traffic accident (40), high-fall injury (36), hanging (20), strangulation (16), and control group (sudden cardiac death, 30). Seven displacement indicators were measured after three-dimensional multiplanar reconstruction. Statistical analyses (Shapiro-Wilk, ANOVA, t -tests) were performed. Five classification algorithms were evaluated for predicting external neck force mechanisms. The head and neck injury group exhibited the highest atlantoaxial subluxation rate (20%), followed by high-fall (13.9%) and thoracoabdominal injury groups (10%). No dislocations were observed in other groups. Significant differences in the anterior atlanto-dental interval (AADI), the posterior atlanto-dental interval (PADI), the left and right vertical distance between the atlantoaxial joint surfaces (LVAJS, RVAJS) were observed across all or individual groups (p < 0.05). Classification results indicated that the energy-based grouping achieved strong overall performance, with both SVM and NB achieving 100% recall and an F1-score of 86.4% for distinguishing high- versus low-energy neck trauma. This study demonstrated that PMCT of the cervical region showed increased values of the atlantoaxial joint displacement indicators AADI, PADI, LVAJS, and RVAJS, which facilitated the identification of different types of external forces applied on the neck and supported their potential utility for energy-level stratification in forensic PMCT assessment.
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