There are three general causes of scoliosis: congenital, usually related to a problem with the formation of vertebrae or fused ribs during prenatal development; neuromuscular (poor muscle control or muscular weakness or paralysis due to diseases like cerebral palsy, muscular dystrophy, spina bifida and polio); and idiopathic (of unknown cause), which appears in a previously straight spine.

The idiopathic form in adolescents is the most common and may have a genetic predisposition. Most cases occur in girls and curves generally worsen during growth spurts. There are also infantile and juvenile forms that are less common and affect a similar number of boys and girls.

Scoliosis may be suspected when one shoulder appears to be higher than the other, or the pelvis appears to be tilted. It is often unnoticeable to an untrained observer, however.

Routine scoliosis screening is now done in junior high school/middle school and many early cases are detected that previously would have gone undetected until they were more advanced.

There may be fatigue in the spine after prolonged sitting or standing. Pain will become persistent if irritation of ligaments results. The greater the initial curve of the spine, the greater the chance for progression of the condition after growth is complete. Severe scoliosis (curves in the spine greater than 100 degrees) may cause breathing (respiratory) problems.