Relationship between rib hump deformity and vertebral rotation in idiopathic scoliosis.

The authors advance the theory that there are two distinct groups of idiopathic scoliosis, of different aetiology and with different potential for development. This is based on the relationship between vertebral rotation and wedge deformity of the vertebral bodies. The rotatory type can be identified, to a statistically significant extent, in the initial phases of thoracic scoliosis. In order to test this hypothesis, we therefore confined our study to cases in which the initial Cobb angle was less than 20 degrees.