Potential Risk of Thoracic Aorta Injury from Excessively Long Right Pedicle Screws in Patients with Left Thoracic Scoliosis: A Computed Tomography Image Study

Abstract

We sought to investigate the changed position of thoracic aorta relative to spine in patients with left thoracic scoliosis and to analyze the potential risks of thoracic aorta injury from pedicle screw insertion in these patients. Twenty patients with left thoracic scoliosis (Group A) and 15 normal subjects with a straight spine (Group B) were included. Axial computed tomography images from T5 to T12 of all these subjects were obtained to measure the aorta-vertebral angle. The percentages of thoracic aorta located anteriorly to the screw trajectory were calculated on both the left and right sides. The average aorta-vertebral angle in Group A was significantly larger than that in Group B at each level (P < 0.05) except T5. In Group A, both left and right pedicle screws might pose threats to the thoracic aorta. The percentages of aortas at risk from the right pedicle screw were high in the apical region. However, in Group B, only the left pedicle screw might pose threats to the aorta. No aorta was found to be at risk of injury from right pedicle screw insertion in Group B. The thoracic aorta often lies anteriorly to the left pedicle screw trajectory in normal subjects, especially in the lower thoracic region. However, the thoracic aorta moves to the right side in patients with left thoracic scoliosis, making a large proportion of patients at risk of injury from right pedicle screw insertion in the apical region.