BACKGROUND: The role of the sternum, if any, in the aetiopathogenesis of adolescent idiopathic scoliosis (AIS) remains unexplored. We evaluated morphological features of the sternum for the first time in individuals with AIS.METHODS: Medical records of a tertiary hospital were reviewed from 2010 to 2018 to identify adolescents with thoracic or thoracolumbar AIS. We included scoliotic patients between 14 and 18 years of age on radiologic evaluation without previous treatment for the disease. A complete history and 3D computed tomography (CT) scan were also prerequisites for study inclusion. We compared the shape and position of the sternum between adolescents with AIS and age-matched individuals as control. The control group was recruited with a random selection from patients attending hospital for extraskeletal reasons during the same period. Using CT, we evaluated the part of the sternum found in the right front quadrant of the axial plane at the level of the middle of the manubrium of the sternum and apical vertebra.  We also provided an evidence-based theory of the sternum involvement in AIS aetiopathogenesis.RESULTS: Twelve scoliotic patients with mean age 16.6 and mean Cobb angle 39.7 degrees were included in the study. No difference was found between groups at the level of the manubrium of the sternum (p =0.486). At the level of the apical vertebra, there was a significant difference of the part of sternum found in the right front quadrant of the axial plane between groups (95 % vs 56 %, p <0.001).CONCLUSIONS: These are preliminary data demonstrating for the first-time morphological differences of the sternum, between AIS and age-matched non-scoliotic individuals. The sternum of adolescents with AIS was more inclined than non-scoliotic controls that could raise the hypothesis of sternum involvement in AIS pathogenesis. HIPPOKRATIA 2018, 22(4): 173-177.