A study on the association between ankylosing spinal disorder and aortic injury in patients with thoracolumbar fracture

Background: There are few case reports of thoracolumbar fracture complicated by aortic injury in patients with the ankylosing spinal disorder (ASD), and the complication rate is not yet known. The objective of this study is to investigate the complication rate of aortic injury with thoracolumbar fracture and to compare the rate between ASD patients and non-ASD patients. <br> Material and Methods: We retrospectively studied computed tomography scans (CT) of 143 patients with thoracolumbar fracture, who underwent their operations in the Department of Emergency and Critical Care Medicine, Saitama Medical Center, between 2014 to 2017. CT revealed ASD in 14 patients (ASD group) and was absent in 129 patients (non-ASD group). <br> Results: Six cases were complicated by aortic injury, 4 (28.6%) in the ASD group and 2 (1.6%) in the non-ASD group. The complication rate in the ASD group was significantly higher compared to the non-ASD group (OR:25.4 95%CI:4.1-156.0). In the patients with aortic injury, the ASD group tended to have more aortic calcification than the non-ASD group. In many patients, the site of aortic injury overlapped with the site of aortic calcification. The fracture type classification by the AO Spine Thoracolumbar Injury Classification System showed that patients with aortic injuries were either B2 or B3, and B3 injuries and were more likely to be complicated by aortic injuries. The majority of ASD patients had anterior extension injuries (B3). <br> Conclusions: ASD was a significant predictor of the complicating aortic injury in thoracolumbar fractures, and aortic calcification and anterior extension injury were considered to be factors that predispose ASD patients to aortic injury. It should be noted that this study only included patients who were admitted to a tertial emergency center, and the results may have been influenced by the bias among the patients.