Assessing the impact of high versus low velocity thoracic trauma: A study of experimental rib fracturing using juvenile pigs (Sus scrofa)

The purpose of this study was to provide experimental data to inform how juvenile porcine torsos behave under conditions of high versus low velocity impact to further understand the effects of compressive trauma on the juvenile torso. The primary goal was to analyze the relationship between rib fracture patterns and the impact direction and velocity to understand how fracture patterns can inform the mechanism of injury. A juvenile porcine model was used to examine the effects of experimental impact to the torso at two different loading rates: static (0.01 m/s), and dynamic (0.4 m/s). The torsos were tested in two distinct impact directions: anteroposterior and lateral. A total sample of 24 juvenile pigs aged approximately 1 to 2 weeks and weighing between 1.3–2.1 kilograms were used. The sample was separated into four groups (SAP – static anteroposterior, SL – static lateral, DAP – dynamic anteroposterior, DL – dynamic lateral), each with six specimens, to assess for differing impact velocities and directions. The experimental variables that were examined were: 1) if the fracture was complete or incomplete, or if only plastic deformation occurred; 2) the side of the fracture; 3) the location of the fracture on the rib; and 4) the location of tension failure. The total number of ribs that were examined was 725 ribs. The results show that there is a relationship between the four experimental groups, and impact velocity and direction. The SAP group produced more incomplete fractures, fractures that occurred mostly on the right side, and at the anterior region, and failed in tension more often on the cutaneal side; the SL group had a small frequency of fractures that did not allow for definitive conclusions to be made; the DAP group produced more complete fractures, fractures that occurred mostly on the right side, and at the posterior neck, and failed in tension more often on the visceral side; the DL group produced mostly complete fractures, at the anterolateral and anterior region, and failed in tension on the visceral side. There were variation among the experimental groups, and some specimens showed no fractures. This study shows that fracture pattern analyses can be potentially used to differentiate the four experimental groups. The current study enhances the knowledge the forensic community has on the effects of compressive trauma to the juvenile torso.