In about 80% of cases, the cause of scoliosis is not known.¹ This is called idiopathic scoliosis. It develops mostly in children and teens and appears to be related to several factors, including genetics, as it often runs in families.

There are two types of scoliosis: nonstructural and structural.

Nonstructural scoliosis involves a curve in the spine, without rotation, that is reversible because it is caused by an underlying condition such as:

• Pain or a muscle spasm.
• An inflammatory condition, such as appendicitis.
• A difference in leg length.

Structural scoliosis involves a curve in the spine, with rotation, that is irreversible and is usually caused by an unknown factor (idiopathic) or a disease or condition such as:

• Disorders that were present at birth (congenital), such as spina bifida, in which the spinal canal does not close properly; or a disorder that affects the formation of bones. Between 5% and 7% of scoliosis cases are caused by congenital abnormalities of the spine, which cause curves in the spine that are more rigid than those caused by idiopathic scoliosis. These curves often get worse as the child grows, especially during the teen years.¹
• Nerve or muscle disorders, such as cerebral palsy, Marfan syndrome, or muscular dystrophy.
• Injuries.
• Infections.
• Tumors.

In adults, scoliosis may result from changes in the spine due to aging (degenerative changes). These degenerative changes may be caused by osteoarthritis or osteoporosis.