Figure 1: Scoliosis of the
thoracic region of the spine.

When the normal spine is viewed from the back, it forms a straight vertical line. Scoliosis is a condition where the spine, as viewed from the back, has one or more curves; these curves are usually called lateral deviations of the spine [see Figure 1]. The vertebrae in scoliosis are abnormally rotated, creating a twisting of the spine and more prominent visibility of the rib cage on one side as it is pushed further laterally. Additional changes to the structure of the vertebral column include a narrowing of the disc spaces on the concave (inner side) aspect of the scoliotic curve and a widening of the disc spaces on the opposite (convex) side [see Figure 3 ]. Scoliosis can be congenital, due to spinal cord injury, or be the result of a number of other causes, such as disease of the hip or the vertebrae, habitually improper posture, neuromuscular conditions (muscular dystrophy), or spinal disorders (degenerative disc disease, spondylolysis). Scoliosis can also occur secondary to other medical conditions (difference in leg length).

When no specific cause can be identified, as is most commonly the case, the scoliosis is said to be idiopathic (without known cause). It can occur in infants (birth to 3 yrs) and in juveniles (4-10 yrs), but it is most commonly seen in adolescents (after 10 yrs). Adult scoliosis is of two types, that which actually arose prior to skeletal maturity at approximately 18 years of age (most commonly idiopathic) and scoliosis which first appears in adulthood, and is most commonly due to degenerative disease of the spine.

X-ray of scoliosis of the spine

Figure 3: X-ray of scoliosis
of the spine. Note the Cobb
angle used to measure the
scoliotic curve.