Objective: To compare thoracic aorta injuries sustained by motorcycle riders with those sustained by pillion passengers in fatal motorcycle collision accidents.

Material and Method: We reviewed the autopsy reports from the Department of Forensic Medicine and Faculty of Medicine at Srinakharinwirot University between January 2011 and December 2015. The research team identified 39 cases of motorcycle accidents with thoracic aorta injuries, which caused the riders 28 deaths and 11 deaths of the pillion passengers. The types of collision and the position of the victim on the motorcycle were obtained from the police reports, which are also included in the study. The characteristic of injuries and fatal causes were evaluated and compared using Chi-square test (χ2).

Results: The result showed that 41% of cases involved in frontal impact collision. For both riders and pillion passengers, the majority of thoracic aorta injuries occurred at the aortic isthmus (57.7%). Thoracic aorta injury was higher in riders than pillion passengers, but these differences were not statistically significant (p = 0.235). In addition, we found that riders were more likely to suffer from impact injuries than pillion passengers, while the pillion passengers were more likely to sustain more tumbling injuries than riders. Sternal fractures and left sided serial rib fractures were predictive of thoracic aorta injury.

Conclusion: Thoracic aorta injuries play a significant role in causing mortalities in motorcycle accidents. The findings in the present study could help guide medico-legal examinations, particularly in identifying riders among victims. The present research provided an insight into decreasing the mortality rate by integrating medical aspects into future motorcycle designs.

Keywords: Thoracic aorta injuries, Motorcycle accidents, Riders, Pillions