Basic principles of idiopathic scoliosis initiation and progression

The etiology of idiopathic scoliosis is still a matter of debate as its common cause had not been found. But some basic principles in its initiation and progression do exist. The curvature of the spine is always accompanied by rotation of the vertebrae and rib cage as ribs are connected by intercostal muscles and cannot spread apart on the convex side when the spine bends. The rib cage rotates instead. The deformation becomes irreversible if bone resorption and remodeling change shape of the ribs and vertebrae or if ligaments are not firm enough. When the rib cage and vertebrae become structurally rotated, the vertebrae lose balanced support from the ribs from both sides. Shear forces from the ribs turn vertebrae even more and push vertebral bodies toward the convexity. Continuous progression of scoliosis starts and can be stopped only with a properly designed brace.