Thus, in patients with multiple injuries and lower rib fractures, contrast-enhanced CT might be indicated even in the setting of a normal clinical examination. Several studies have demonstrated a high prevalence of radiographically detected rib fractures in patients with aortic injury, although the positive predictive value is low. In a large prospective multicenter trial involving 50 trauma centers in North America, Fabian et al [20] reported multiple rib fractures in 46% of 274 patients with blunt aortic injury. Mirvis et al [21] found fractures of ribs 1 through 4 in 18% of 41 patients with traumatic aortic injury proved by angiography but with a positive predictive value of only about 21%. Lee et al [22] studied 548 patients who underwent angiography to evaluate for aortic injury and concluded that rib fractures were the only type of thoracic skeletal injury that had a higher incidence in patients with aortic injury (58%) versus those without aortic injury (43%), but the positive predictive value was only 14.8%. This has also been shown at autopsy, where Williams et al [23] retrospectively reviewed 530 motor vehicle fatalities. In 90 victims, 105 aortic injuries were found, and 78% had multiple rib fractures, including 42% with fractures of the first rib. In contrast, there is some evidence that rib fractures detected with CT (given the increased sensitivity) may not be associated with an increased risk of aortic injury. A review of 185 patients with rib fractures detected on spine CT found no association between presence of first-rib or second-rib fracture and the incidence of aortic injury on subsequent CT [24]; however, ribs 3 through 12 were not assessed. Increased likelihood of injury to the adjacent subclavian and innominate vessels has been reported with displaced first-rib and second-rib fractures, but this injury can usually be suspected on clinical grounds or from a chest radiograph [25].
Rib Fractures. Thus, in patients with multiple injuries and lower rib fractures, contrast-enhanced CT might be indicated even in the setting of a normal clinical examination. Several studies have demonstrated a high prevalence of radiographically detected rib fractures in patients with aortic injury, although the positive predictive value is low. In a large prospective multicenter trial involving 50 trauma centers in North America, Fabian et al [20] reported multiple rib fractures in 46% of 274 patients with blunt aortic injury. Mirvis et al [21] found fractures of ribs 1 through 4 in 18% of 41 patients with traumatic aortic injury proved by angiography but with a positive predictive value of only about 21%. Lee et al [22] studied 548 patients who underwent angiography to evaluate for aortic injury and concluded that rib fractures were the only type of thoracic skeletal injury that had a higher incidence in patients with aortic injury (58%) versus those without aortic injury (43%), but the positive predictive value was only 14.8%. This has also been shown at autopsy, where Williams et al [23] retrospectively reviewed 530 motor vehicle fatalities. In 90 victims, 105 aortic injuries were found, and 78% had multiple rib fractures, including 42% with fractures of the first rib. In contrast, there is some evidence that rib fractures detected with CT (given the increased sensitivity) may not be associated with an increased risk of aortic injury. A review of 185 patients with rib fractures detected on spine CT found no association between presence of first-rib or second-rib fracture and the incidence of aortic injury on subsequent CT [24]; however, ribs 3 through 12 were not assessed. Increased likelihood of injury to the adjacent subclavian and innominate vessels has been reported with displaced first-rib and second-rib fractures, but this injury can usually be suspected on clinical grounds or from a chest radiograph [25].