[Biomechanical analysis of the pulmonary trauma by localized blunt force--thoracic force-deflection in pigs]

Thoracic force-deflection characteristics have been measured in the living little pigs as a step towards the analysis of thoracic injury in the field of forensic medicine. Mechanisms of injury by hand impact with a small stone were investigated by means of high speed video/camera and load cell. Initial velocity by hand impact ranges from 5.8 to 11.1 m/s, with corresponding peak force from 24 to 122 kgf. The thoracic force-deflection of the pig shows a progress change with increasing impact velocity, showing more of a spring-mass like response with an initial linear region of stiffness during a short interval immediately after the impact. Peak force up to 122 kgf was developed for 77 mm in the localized thoracic displacement with rib fractures and serious lung injury. A few rib fractures occurred with initial velocity near 9 m/s and displacement near 50 mm, these data suggest an outbreak limit of rib fractures of the little pig.