Scoliosis Curvature Follows Thoracic Organ Orientation

Study Design. Retrospective cohort study, Level of Evidence III. Objective. To determine the relationship between internal organ orientation and adolescent idiopathic scoliosis (AIS) convexity directionality. Summary of Background Data. AIS affects 2% to 3% of the general population and demonstrations 80% to 99% right thoracic curve convexity. The mechanism of AIS as well as explanation for right-sided predominance is largely unknown. Methods. A retrospective chart review of all patients with dextrocardia from 2008 to 2018 was performed at a single institution. Upright chest x-rays and scoliosis x-rays were evaluated for scoliosis by measurement of Cobb angle. Chart review was performed to extract age, advanced imaging results, and surgical intervention. Results. Of 110 patients identified with dextrocardia, 19 patients exhibited radiographic features consistent with AIS (Cobb angle >10 degrees). Fifteen (79%) of these patients demonstrated left-sided thoracic curvature. Six patients showed isolated dextrocardia with normal abdominal organ orientation; five patients (83%) showed left-sided thoracic curvature. There was not a statistical difference with regards to sex or curve severity. Magnetic resonance imaging (MRI) was performed on five patients with left-sided curvature without evidence of intra-spinal pathology. Conclusion. Dextrocardia shows increased incidence of AIS in both male and female patients. Left-sided thoracic curvature in cases with concurrent dextrocardia may not be associated with intra-spinal pathology as seen in the general population. These data suggest that thoracic organ orientation affects AIS convexity directionality.