Medical Health Encyclopedia

Among adults, previous reports have indicated a prevalence of scoliosis of up to 32%. But a recent study of 75 healthy adults aged 60 years and older with no known history of scoliosis or prior spine surgery suggested a rate of 68%. However, scoliosis was not linked to physical or social impairment in this population.

Defining Scoliosis by the Shape of the Curve

Scoliosis is often categorized by the shape of the curve, usually as either structural or nonstructural.

• In structural scoliosis, the spine not only curves from side to side, but the vertebrae also rotate, twisting the spine. As it twists, one side of the rib cage is pushed outward so that the spaces between the ribs widen and the shoulder blade protrudes (producing the rib-cage deformity, or hump). The other half of the rib cage is twisted inward, compressing the ribs.
• A nonstructural curve does not twist but is a simple side-to-side curve.

Other abnormalities of the spine that may occur alone or in combination with scoliosis include hyperkyphosis (an abnormal exaggeration in the backward rounding of the upper spine) and hyperlordosis (an exaggerated forward curving of the lower spine, also called swayback).

Click the icon to see an image of kyphosis.

Defining Scoliosis by Its Location

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The location of a structural curve is defined by the location of the apical vertebra. This is bone at the highest point (the apex) in the spinal hump. This particular vertebra also undergoes the most severe rotation during the disease process.

Defining Scoliosis by Its Direction

The direction of the curve in structural scoliosis is determined by whether the convex (rounded) side of the curve bends to the right or left. For example, a doctor will diagnose a patient as having right thoracic scoliosis if the apical vertebra is in the thoracic (upper back) region of the spine and the curve bends to the right.

Defining Scoliosis by Its Magnitude