What is scoliosis?

Scoliosis is a progressive musculoskeletal condition that results in the curvature or rounding of the spine¹. Scoliosis is typically defined as a curvature and rotation of the backbone (spine) that measures 10 degrees or more and causes three-dimensional deformity.

The musculoskeletal system provides support, form, movement and stability to the body. The spine, which forms a vital part of this system, is a column of bones (known as vertebrae) that aid in support of the entire body.

A healthy spine will have a normal curvature when looking at it from a side view, when looking at it from the front (with the help of an X-ray), it will appear straight. In scoliosis, the spine has a “C” or “S” shaped appearance from the front, making it look as though the affected person is leaning to the side.

Curvature of the spine as a result of scoliosis may occur on the left, right or both sides. Both the mid spine, also known as thoracic spine and the lower spine, known as lumbar spine, may be affected by the condition. Vertebrae or backbones can also rotate and twist on one another as a result of scoliosis.

Scoliosis can affect people of all ages, however, the condition is mostly seen in those over the age of 10. Severe and progressive forms of the condition are more commonly seen in more girls than boys, although the reason for this is still unknown.

Scoliosis is thought to be a hereditary condition to some degree, meaning that adults with the condition may sometimes pass it on to their children. While the severity of the curvature is not passed from one generation to the next, the condition itself sometimes is. That said, only approximately 20 to 25% of people who have relatives with scoliosis will develop the condition themselves², and as such experts believe that in addition to a genetic predisposition, certain environmental factors may also contribute to its development.

Roughly 10% of adolescents have some form of scoliosis, with curvatures ranging from mild to severe. In 80% of scoliosis patients, the cause of the condition is unknown² and as such, is referred to as idiopathic scoliosis².

Curvature disorders of the spine

When abnormalities of the spine occur due to a specific condition or trauma, the natural curvature is exaggerated or misaligned in specific areas.

The spine has a series of normal curves that can be seen when viewing it from the side. These curves allow the body to better absorb loads applied to the spine by the weight of the body. There are three types of spinal curvatures, two of which are natural and one of which is not:

1. Lordotic curvature: The cervical spine (neck) and lumbar spine (lower back), generally have normal inward curve.
2. Kyphotic curvature: The thoracic spine or upper back, has natural outward curve at the level of the ribs.
3. Scoliotic curvature: This is an abnormal sideways curvature of the spine.

A small degree of both kyphotic and lordotic curvature is normal and healthy, however, when too much of either curvature are present the terms kyphosis (or hyperkyphosis) and lordosis (or hyperlordosis) are used in a clinical setting. Abnormal is another term that may be used to describe these curves.

The below information simply explains the difference between lordosis, kyphosis and scoliosis (bear in mind, lordosis and kyphosis may occur alone or in combination with scoliosis):

• Lordosis/hyperlordosis – This condition, also known as swayback, refers to a significant inward curve of the lumbar (lower) spine just above the buttocks.
• Kyphosis/hyperkyphosis – This condition, also known as a hunchback, is characterised by an abnormal rounding of the upper back (by more than 50 degrees), causing a rounding or hunching of the shoulders (also referred to as Scheuermann's disease or Scheuermann’s kyphosis).
• Scoliosis – This refers to an abnormal sideways curvature of the spine (with a lateral deviation of 10 degrees or more) that resembles an S or C shape, causing a three-dimensional deviation of the spinal axis and deformity. This condition often progresses leading to the development of additional curves on either side of the body as the spinal bones (vertebrae) twist and rotate.

In medical literature, more specified terms are often used to describe the different curvature forms of scoliosis, these include:

• Kyphoscoliosis – This refers to a combination of lateral (sideways) and outward curvature of the spine.
• Dextroscoliosis -This term refers to when the spine curves to the right side of the body.
• Rotoscoliosis (also known as rotatory sclerosis) – This refers to the curvature of the spine that not only curves to the side, as is the case with classic scoliosis, but is also associated with rotation of the vertebral column.
• Levoconvex – This refers to a spinal curvature that is inclined to the left.
• Thoracolumbar – This term refers to a spinal curvature that is associated with both the lumbar (lower) and thoracic (upper) areas of the spine.

^References:

^{1. PubMed Health. Scoliosis. Available: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024966/ [Accessed 05.09.2017]}

^{2. University of Maryland Medical Centre. 2012. Scoliosis. Available: http://www.umm.edu/health/medical/reports/articles/scoliosis [Accessed 07.09.2017]}