Pelvic Injuries in Side Impact Collisions: A Field Accident Analysis and Dynamic Tests on Isolated Pelvic Bones

The accidentological studies dealing with automotive side collisions suggest that the pelvis is very vulnerable. Car manufacturers are more and more concerned with the protection of the occupant in lateral impact, but there is a lack of knowledge of the behavior of the pelvic bony structure and of its biomechanical tolerances. This knowledge however is essential in order to optimize protection devices and car structures with regard to the security of the occupants. The main goal of this study is thus two-fold:

• First, a field accident analysis was carried out in order to document the lesions and the injury mechanisms encountered in lateral impact. The accident database of the Laboratory of Accidentology and Biomechanics (LAB) was used and a sample of 219 injured occupants sustaining 381 injuries in lateral collision enables to evaluate the most frequent injuries and their location. Those injuries were also analyzed with regard to the car characteristics.
• Second, an experimental study of the pelvic bony structure subjected to dynamic loads was carried out in order to document its biomechanical behavior and its lesion threshold. 12 pelves were tested under side loading conditions. Displacement, accelerations, applied force, and local strains of the pubic rami were obtained.

From those two parallel studies, the main conclusions drawn out were:

• There was a good agreement between the real life observations and those coming from the dynamic tests.
• The fracture threshold was well bordered by the chosen energy level of impact, and consequently, a first corridor including the behavior of the pelvic bony structure up to the level of injury is proposed.