Investigation of Traumatic Rupture of the Aorta (TRA) using Simulated Real-World Accidents Involving Aortic Injuries

Traumatic rupture of the aorta (TRA) is one of the leading causes of death in automotive crashes. The risk of fatality is higher if the injury is not detected and treated promptly. Numerous laboratory experiments and retrospective studies with focus on TRA have yielded limited success. The use of numerical surrogates has become increasingly important in investigating injuries such as TRA. Four real-world accidents with aortic injuries to the occupants were obtained from the national automotive sampling system (NASS) database. Two crashes were side impact, and two were frontal crashes. Each case was numerically reconstructed in two phases. For the first phase, the car-to-car interaction was simulated using vehicle finite element (FE) models obtained from the national crash analysis center (NCAC) public model archive. They were modified to better represent the actual crash vehicles. These simulations were validated qualitatively and quantitatively against available crash photographs and crush data. For the second phase, the interaction between the occupant and the interior of the automobile was simulated using the results of the first simulation as input. The occupant was a whole-body human FE model developed at Wayne State University (WSU), and represents the midsized male. The model includes descriptions of all major thoracic and abdominal organs, major blood vessels including the aorta, and all major bony structures. For the two side impact crashes, the peri-isthmic region demonstrated the greatest maximum principal strain (MPS) and longitudinal stress (LS). For the frontal crashes, the junction of the ascending aorta and the aortic arch was the region of greatest MPS and LS. The strain and stress were computed and compared for the peri-isthmic region of the aorta since it is most relevant to clinically observed TRA. Peak MPS and peak LS averaged within the peri-isthmic region of the aorta for the second phase FE simulations ranged from 0.072 to 0.160, and 0.93 MPa to 1.58 MPa, respectively. The aortic strain and stress patterns and internal kinematics observed in the FE simulations can help to better understand the injury mechanisms of TRA. The results also have application to the design of experiments to study TRA in cadavers. INTRODUCTION T RA is believed the second most common cause of fatality (Sauaia et al., 1995) associated with motor vehicle crashes (MVC). It is considered to be responsible for approximately 8000 fatalities every year in the United States (Mattox, 1989). Approximately seventy percent of all TRA result from high speed MVC