The spine is made up of twenty-four individual bones called vertebrae that are separated by discs. The discs allow the spine to be flexible.
There are three regions of the spine: seven cervical (neck) vertebrae, twelve thoracic (chest) vertebrae and five lumbar (low back) vertebrae. In addition, there are five fused vertebrae below the lumbar spine that make up the sacrum. The spinal column houses and protects the spinal cord. Spinal nerves project out from the spinal cord through spaces between each of the vertebrae.
Viewed from the front or back, the spinal column should be straight. When scoliosis is present, you will see a sideways shift of the spine to the right or left. Approximately 10% of the population has small curves (less than ten degrees), which are of no consequence to function or health. This condition is called Spinal Asymmetry.
When a diagnostic x-ray is done, the curve of the spine is measured in degrees, as an angle, and this is called a Cobb angle. Scoliosis is defined as a curve greater than ten degrees. It is most common in the thoracic and lumbar regions of the spine and can involve one or both of these regions. The most common curve pattern is a right thoracic curve.
There are naturally occurring curves in the spinal column when it is viewed from the side (laterally). Swayback (lordosis) is normally present in the cervical and lumbar regions while round back (kyphosis) generally exists in the thoracic spine.
Scoliosis can arise from a number of underlying conditions, but the most common form is idiopathic, which means “cause unknown.”
Scientists have identified that idiopathic scoliosis is a genetic condition and continue to work to isolate the combination of individual genes that cause scoliosis. A test has been developed that may help to determine the risk of progression of scoliosis (whether or not the curve will get bigger). This may eventually allow for earlier diagnosis and more accurate selections of the “best” treatment for each patient.
There is some evidence to suggest that uneven growth rates between the anterior (front) portion of the vertebrae and posterior (back) portion of the vertebrae may be one cause of scoliosis.
Idiopathic scoliosis is thought to be present in two to three percent of adolescents. One in five hundred of these will require active treatment and only one in five thousand have curves that progress to the degree where surgery is recommended. Girls and boys are equally affected by small degrees of scoliosis. Girls, however, are eight times more likely to develop progressive curves.
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