Preliminary ultrasonographic study on the thickness and elasticity of abdominal muscles in adolescents with left-side thoracolumbar/lumbar scoliosis

To compare the morphological and biomechanical characteristics of abdominal muscle characteristics between AIS (adolescent idiopathic scoliosi) patients and healthy controls. This study was designed as a case-control observational study. It involved 43 adolescents aged 10 to 17 years with left-side thoracolumbar/lumbar scoliosis and 43 age-matched healthy adolescents. High-frequency B-mode ultrasound and shear wave elastography were employed to measure the thickness and elasticity of the external oblique (EO), internal oblique (IO), and transverse abdominal muscles (TrA) in both supine and standing positions. Muscle thickness was recorded at the end of normal exhalation, and the difference in thickness between maximum inhalation and exhalation (i.e., respiratory activity). Muscle elasticity was recorded at the end of calm exhalation. The results revealed that in the supine position, the thickness of IO and TrA on both sides was smaller in adolescents with scoliosis compared to healthy controls (P right IO = 0.041, P left IO = 0.001; P right TrA = 0.040, P left TrA = 0.007), while the respiratory activity in TrA was significantly lower ( P = 0.049). In both supine and standing positions, the elasticity values of IO and TrA on both sides were higher in the scoliosis group than in the healthy control group ( P < 0.05). In both positions, IO on the concave side was thicker than that on the convex side in left-side scoliosis patients (P supine = 0.007, P standing = 0.005), but there was no statistically significant difference in the elasticity of the abdominal muscle groups on either side in the scoliosis group. There are varying degrees of difference in the thickness and elasticity of IO and TrA between patients with left thoracolumbar/lumbar spinal curvature and healthy adolescents, and the muscles on the convex side of the curve are relatively weaker and more stiffness. These characteristics should be considered during conservative treatment to enhance treatment efficacy.