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Scoliosis is a condition that involves an abnormal side-to-side curvature of the spine. If left untreated, it can lead to chronic back pain and progressive spinal deformity, and can even affect the heart or lungs. Most cases, however, are mild. Scoliosis cannot be cured, but it is highly treatable. An estimated 2 to 3 percent of the population has some degree of lateral curve of the spine, but the vast majority will never require treatment.

Most scoliosis cases are classified as idiopathic, meaning there is no known cause. It most often develops in childhood, during times of rapid growth prior to puberty, and is more common in girls than in boys. Scoliosis can also occur in adulthood. This can either be because the condition was undetected and untreated during childhood or because it developed from degeneration of the spine with aging.

Children are generally screened for scoliosis in fifth or sixth grade during routine pediatric exams or in school. If scoliosis is diagnosed, treatment may involve observation, bracing, or surgery, depending on the severity and location of the curve, the amount of growth remaining, and documented progression of the curve.

Need-to-Know Anatomy

The spine is made up of 33 interlocking bones, called vertebrae, that stack up at a slight angle to form the spine's S-shaped curve. This distinctive curvature helps the spine to absorb the shock of movement while still supporting the body's weight. The vertebrae are connected to each other by disks and connective tissue and grow progressively larger and stronger from top to bottom. The seven delicate cervical (neck) vertebrae support the head; the larger 12 thoracic (chest) vertebrae bear the weight of the arms and trunk; and the five thickest and sturdiest lumbar (lower back) vertebrae carry the weight of the entire body. Finally, at the base of the spine are nine fused vertebrae that make up the sacrum (the back wall of the pelvis) and coccyx (tailbone).

Viewed from behind, a normal spine appears straight, and the trunk is symmetrical. People with scoliosis, however, have spines that curve laterally more than 10 degrees, appearing in an X-ray as an "S" or a "C." The curve can bend to the left or right, and may be in the thoracic or lumbar spine or in both areas (thoracolumbar). Scoliosis is a three-dimensional deformity and also involves rotation of the spine. This is why there is often a rib hump associated with thoracic scoliosis and asymmetric-appearing hips with lumbar curves.


The most common type of scoliosis is known as idiopathic, meaning there is no known single cause. In rare cases, a spinal curvature may be the result of a birth defect that affects the development of the vertebrae. This often occurs with other congenital problems and is known as congenital scoliosis. Another type, neuromuscular scoliosis, is caused by an underlying disorder, such as cerebral palsy, Duchenne muscular dystrophy, or spina bifida.

Risk Factors

Scoliosis tends to run in families. Researchers continue to work on identification of genes associated with scoliosis.

Females are more likely to develop scoliosis. As curves become larger (greater than 20 degrees), so does the proportion of females compared to males. Also, spinal curves in females often progress further than in males.

Last reviewed on 01/03/2008

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