Pathogenesis of scoliosis.

Scoliosis often occurs in otherwise normal individuals or it may be associated with many widely differing diseases. The curve patterns are fairly uniform and the vertebrae always rotate in the frontal and horizontal planes producing convex side rotation with little displacement of the spinuous processes. Many small curves do not increase. Progressive scoliosis increases linearly and the rate of increase accelerates at puberty. No endocrine abnormalities have been observed in these patients. Usually the deformity is not caused by abnormal vertebral growth nor by abnormal collagen in verterbral ligaments. The glycosaminoglycans of nucleus pulposus are decreased in patients with idiopathic scoliosis. We speculate that loss of proteoglycans will affect the viscoelastic properties of the intervertebral discs which may result in permanent deformation. The etiology of scoliosis appears to be multifactorial with a genetic tendency to the deformity which is triggered in different individuals by different factors, some medical, some mechanical and some genetic.