200 Section - Immediate Biomechanical Effects of Schroth-Based Corrective Maneuvers on Spinal Alignment and Paraspinal Muscles in Adolescent Idiopathic Scoliosis

Objectives : This study aimed to quantify the immediate effects of four specific Schroth-derived corrective maneuvers on three-dimensional spinal alignment and paraspinal muscle morphology in adolescents with idiopathic scoliosis (AIS), and to compare these responses between Rigo type A (single thoracic) and type B (double major) curve patterns.

Design: A cross-sectional within-subject study was conducted with 40 AIS participants (20 Rigo A, 20 Rigo B). Each performed four corrective maneuvers (Muscle Cylinder, Door Handle, self-corrected standing, self-corrected sitting). Real-time ultrasonography captured dynamic changes in spinal alignment parameters (coronal, sagittal, and axial planes), while B-mode ultrasound simultaneously assessed volumetric and symmetry changes of paraspinal muscles at key vertebral levels. Measurements were compared between habitual posture and each corrective condition. The influence of spinal flexibility, assessed via side-bending, on the observed changes was also analyzed through correlation.

Results: All corrective maneuvers significantly reduced the primary coronal curve. Axial derotation was prominent in Rigo A during Muscle Cylinder and Door Handle exercises, and in the lumbar curve of Rigo B across all tasks. Sagittal alignment changes were more notable in Rigo B. Paraspinal muscle activation varied, with Muscle Cylinder promoting the most symmetrical bilateral increase in muscle volume. A negative correlation was found between baseline spinal flexibility and the magnitude of sagittal plane change during correction, suggesting greater flexibility may reduce the need for active muscular compensation to maintain stability.

Conclusion: Schroth-based corrective maneuvers produce immediate, measurable improvements in spinal 3D alignment and paraspinal muscle activity in AIS, with effects varying by exercise and curve type. Muscle Cylinder demonstrated the most favorable combined effect. These findings support the biomechanical rationale for specific exercises and highlight the importance of tailoring rehabilitation strategies to individual curve morphology for optimal immediate postural correction.