Rib fracture patterns and radiologic detection--a restraint-based comparison

This paper presents a study of the rib fracture patterns generated in simulated frontal collisions and the visibility of the rib fractures on plain film radiographs. Using 29 cadaver subjects, rib fractures were identified on oblique, lateral, and anteroposterior chest films by five radiologists independently and were compared with fractures found during a detailed necropsy. Physical, geometric, and experimental factors demonstrated an influence on the ability of a radiologist to identify rib fractures on an x-ray. Specifically, the restraint system configuration, the total number of fractures, the circumferential location of the fracture, the rib number, and the aspect (right or left) affected fracture identification. The results verify that torso belt loading produces rib fractures generally located along the path of the belt whereas superimposed airbag loading results in a more distributed and posterolateral fracture pattern. A higher proportion of rib fractures was identified on x-ray for occupants restrained by only a belt (44% of fractures) than for occupants restrained by both a belt and an airbag (24% of fractures). Overall, less than 40% of the rib fractures were detected upon an initial examination of radiographs. After being provided with the location of all fractures, detection increased to 49%. On average, occult rib fractures resulted in an average underreporting of injury severity of more than one AIS level.