A rare case of fatal delayed aortic rupture caused by repeated microtrauma from a posterior rib fracture.

Sharp bone fragments can cause damage to major blood vessels or internal organs during the subacute or chronic phases, even if such bone fracture itself does not immediately affect hemodynamics or the patient's condition. Herein, we report a fatal case of delayed aortic rupture in which the anatomically significant relationship between a posterior 8th rib fracture and descending aortic injury was initially overlooked. The patient initially appeared hemodynamically stable under conservative management for fall-related injuries; however, he suddenly collapsed on hospitalization day 10 and subsequently died. Autopsy revealed a full-thickness perforation of the descending thoracic aorta due to the sharp edge of the fractured rib. Retrospective review of premortem computed tomography demonstrated that the rib fracture fragment was extremely close to the aortic wall; however, this finding did not receive sufficient clinical attention. Histologically, the aorta exhibited partially organized adventitial injury, providing objective evidence of repeated premortem contact between the rib fragment and the aortic wall. These findings strongly support delayed traumatic aortic rupture secondary to rib fracture, rather than spontaneous vascular disease. Posterior left lower rib fractures can precipitate delayed and fatal aortic injury. Following initial screening for life-threatening conditions, rib fractures are often managed conservatively, with only pain control and respiratory support. However, posterior left lower rib fractures may warrant consideration for surgical intervention, both for emergent and even prophylactic purposes. This case provides unique pathological and clinical insights into a rare but lethal complication of blunt thoracic trauma, expanding current understanding of delayed aortic injury due to posterior rib fractures.