In most cases, the cause of scoliosis is not known. This is called idiopathic scoliosis. It develops mostly in the preteen and teen years. It often runs in families.
There are two types of scoliosis: nonstructural and structural.
Nonstructural (functional) scoliosis
Nonstructural (functional) scoliosis involves a curve in the spine that is reversible because it is caused by a condition such as:
- Pain or a muscle spasm.
- A difference in leg length.
Structural scoliosis involves a curve in the spine that is irreversible. It 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. These curves can be harder to correct. They often get worse as the child grows, especially during the teen years.
- Nerve or muscle disorders, such as cerebral palsy, Marfan's syndrome, or muscular dystrophy.