Spatial Relations Between the Vertebral Body and the Thoracic Aorta in Adolescent Idiopathic Scoliosis

An analysis of computed tomography images of patients with adolescent idiopathic scoliosis.To evaluate the spatial relations between the vertebral body and the thoracic aorta and to verify the safety of anterior instrumentation surgery.Recent studies have suggested that the aorta is positioned more laterally and posteriorly in patients with idiopathic scoliosis than in normal patients; however, no study used rib heads as references in the analysis.Computed tomography images of the whole thoracic spine of 10 patients with adolescent idiopathic scoliosis were analyzed. A line that passed the anterior edge of the bilateral rib heads was regarded as the virtual passage of the screw used for anterior instrumentation surgery. Whether this line crossed the aorta was investigated. A distance between the vertebral body and the aorta was measured along this line.The aorta was located more posteriorly between T6 and T9. At these levels, the virtual passage of the screw crossed the aorta in 33 of 40 vertebrae (83%). At seven vertebrae in 5 patients, this passage crossed the aorta and the distance was less than 2 mm. Of these, four were T6, two T7, and one T8.In some patients with adolescent idiopathic scoliosis, the aorta can be located in the direction of the screw passage and close to the vertebral body. Accordingly, when planning anterior instrumentation surgery for right thoracic curve, surgeons should pay attention to these spatial relations.