Background: Adolescent Idiopathic Scoliosis tends to be complicated with spine and ribcage deformities. In addition to the coronal curvature, among the features of right thoracic scoliosis, flat chest, ribcage rotation, cardiac compression and an aortic left shift are also observed. Aorta is known to shift in a leftward direction, especially at the mid-thoracic level. The cause of aortic left shift in scoliosis is not known. To clarify the features of a scoliosis deformity, especially the relationship of the aortic left shift and the flat chest in scoliosis, we investigated the CT scan images of scoliosis patients.
Methods: For the measurement of scoliosis patients, the pre-operative CT scans of 22 patients with non-congenital right thoracic scoliosis were recruited. For controls, 25 age-matched non-scoliosis patients were recruited. The aortic location, the ribcage rotation angle and chest depth were measured by CT scan. The chest depth was defined as the smallest inner chest cavity depth between the anterior vertebral body and the anterior inner chest wall.
Results: Chest depth in scoliosis patients was found to be significantly narrower than the control group at every thoracic level, from T6 to T11. The aortic left shift was significantly larger in scoliosis patients at all measured levels. The chest depth correlated with an aortic leftward shift (r = 0.49). The aortic location was found to be correlated with the ribcage rotation angle (r = -0.52), and the ribcage rotation angle correlated with the thoracic side curvature (r = 0.61)
Conclusions: In right thoracic scoliosis, an aortic left shift correlated with both flat chest and the ribcage rotation.