Imaging of lower extremity trauma from Boston Marathon bombing.

The goal of this study is to describe the imaging features of lower extremity blast injuries in patients encountered in the radiology departments from the Boston Marathon bombings. A total of 115 patients presented to four acute care hospitals on April 15, 2013, 43 of whom presented with lower extremity injuries and were included in this study. The imaging findings of primary, secondary, tertiary, and quaternary blast injuries were evaluated. Forty-one of 43 patients sustained secondary blast injuries to the lower extremities with 31 patients (70 %) having retained shrapnel, seven patients (16 %) having soft tissue lacerations without retained shrapnel, and ten patients (23 %) having lower extremity amputation (7 % double amputees). Eight of these patients (20 %) had lower extremity fractures, and five patients (12 %) had vascular injuries. Two of the 43 patients (5 %) had only tertiary injuries, and five of 43 patients (12 %) were noted to have lower extremity burns, consistent with quaternary blast injury. No primary blast injury occurred in the lower extremities. A vast majority of lower extremity injuries were from secondary blast injury, most commonly from retained shrapnel in 70 % of patients and 23 % of patients sustaining lower extremity amputation. Retained shrapnel in the lower extremity was most commonly ball bearings and pressure cooker fragments, and most injuries affected the leg, followed by the thigh and foot.