What Is Scoliosis?

Scoliosis is defined as a structural alteration in the natural curves of the spine. It is a three-dimensional condition, involving rotation of the spine, one or more lateral curves (to the right or left when viewed from behind), and changes in the spine’s natural curves—kyphosis (upper back) and lordosis (lower back) when viewed from the side. These changes may appear as structural flatback, hyperkyphosis, reduced lumbar lordosis, or hyperlordosis.

The diagnosis of scoliosis is made based on an X-ray, using measurement of the Cobb angle and spinal rotation. A structural scoliosis is defined by a Cobb angle greater than 10° along with evidence of vertebral rotation or torsion.

Prevalence and Development

Idiopathic scoliosis affects approximately 2–3% of the population, and many cases do not require treatment. However, scoliosis can progress rapidly during periods of rapid growth—particularly between the ages of 10 and 13—though growth patterns vary by individual. Progressive scoliosis is more frequently seen in girls than in boys.

Spinal Curves and Classification

When viewed from behind, scoliosis may appear as either a C-shaped or S-shaped curve, bending to the right or left. There are several types of scoliosis based on the location of the curve:

• Thoracic scoliosis: located in the ribcage region
• Thoracolumbar scoliosis: at the junction between the thoracic and lumbar spineLumbar scoliosis: located in the lower back

The primary curve is the one with the largest Cobb angle. Additional, smaller curves may develop to compensate for the main curve. A curve bending to the right is called dextroconvex, while one bending to the left is called sinistroconvex.

Physical Signs of Scoliosis

Signs of scoliosis may include asymmetry in the shoulders, waist, or pelvis. For example, one shoulder may sit higher or protrude forward. This side may also show a prominent shoulder blade (“winging”) that is elevated and shifted outward.

There may also be torsion of the ribcage, where the ribs rotate backward on one side and forward on the other.