Overview of Scoliosis

Scoliosis (pronounced sko-lee-O-sis) is a condition in which the backbone, or spine, curves abnormally. Scoliosis also is known as curvature of the spine. In most cases, scoliosis is mild and does not require treatment.

The spine is made up of 33 bony segments called vertebrae. These bones are arranged in a long vertical column and are cushioned and separated by intervertebral discs. The natural curve of the spine allows us to move, balance, and walk normally. In scoliosis, the involved vertebrae rotate and cause the spine to curve sideways, or laterally.

Scoliosis usually develops gradually over time. The condition commonly affects the vertebrae in the middle back (thoracic spine) or the lower back (lumbar spine). Rarely, the vertebrae in the neck (cervical spine) are affected. In some cases, a second curve develops in the opposite direction to compensate for the abnormal spine curvature. When this occurs, the spine can take on an "S" shape.

Types of Scoliosis

There are several different types of scoliosis. In more than 80 percent of cases, the cause for spine curvature is unknown (called idiopathic scoliosis). Although it can occur at any age, idiopathic scoliosis is more common in older children (between the ages of 10 and 12) and adolescents. Idiopathic scoliosis often develops during a growth spurt (i.e., period of fast growth).

Scoliosis can be classified as structural scoliosis (fixed spinal deformity) or nonstructural scoliosis (usually temporary, not caused by a structural defect in the spine itself). The condition also may be characterized according to the following:

  • Age of onset (e.g., infantile [develops in children younger than 3], juvenile [develops in children between 3 and 10 years of age], adolescent [develops in children over the age of 10])
  • Cause for the condition (e.g., idiopathic, medical condition, congenital abnormality)
  • Degree of the curve (e.g., greater than 10 degrees, less than 20 degrees, more than 30 degrees)
  • Direction of the curve (e.g., left, right)
  • Location of the curve (e.g., thoracic spine, lumbar spine)
  • Shape of the curve (e.g., "C" curve, "S" curve, double curve)

Idiopathic right thoracic scoliosis (curvature to the right in the middle back with no known cause) less than 20 degrees is the most common type of scoliosis.

Incidence and Prevalence of Scoliosis

Scoliosis affects approximately 3 percent of children and adolescents over the age of 10. In most cases, spine curvature is mild and does not require treatment. Although the condition occurs in both boys and girls, scoliosis that requires treatment is 4–5 times more common in girls.

Scoliosis incidence is higher in children with a family history of the condition. It also occurs more often in children with certain other medical conditions, such as neuromuscular diseases, connective tissue disorders, and rheumatic diseases.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 27 Aug 2008

Last Modified: 05 Oct 2015