In order to investigate the morphological and biomechanical characteristics of anterolateral part of core muscles in adolescent idiopathic scoliosis (AIS), the muscle thickness and elasticity of obliquus externus (OE), obliquus internus (OI) and transversus abdominis (TrA) were measured using high frequency B-mode ultrasound and shear wave elastography in supine and standing positions, respectively. 25 patients aged 10~17 years with right-side thoracic scoliosis (Cobb angle was 21.36°±8.26°) and 25 healthy adolescents were observed in this study. Muscle thickness was recorded as the thickness value at the end of normal expiration and the contraction thickness difference (CTD, thickness difference between the end of maximum inspiration and the end of maximum expiration), and muscle elasticity was recorded as the measurement after the end of normal expiration. About thickness, the left OE was thinner (P=0.03) and had a greater CTD (P=0.04) than those in healthy group in supine position.Only TrA in side-difference (difference between convex and concave side) in scoliosis group was statistically significant (P=0.02). In standing position, there was no significant difference in absolute thickness and CTD between scoliosis and healthy group. For elasticity, scoliosis group had greater elasticity of the concave external abdominal oblique than the convex side in supine position (P=0.03); only left TrA in scoliosis group had greater elasticity than it in healthy group in standing position (P=0.03).It can be concluded that the thickness and elasticity of EO and TrA in adolescents with mild-to-moderate idiopathic thoracic scoliosis differ in varying degrees from those of healthy adolescents. More attention to those abdominal muscles could be paid in conservative treatment of scoliosis.

idiopathic scoliosis; core muscles; shear-wave elastography; adolescent; exercise therapy