What causes scoliosis

Most scoliosis has no single identifiable cause. Doctors call this idiopathic scoliosis, which means the spine curves without an obvious reason. It accounts for about 80 percent of all scoliosis cases. The curve develops during growth, most often between ages 10 and 18, and tends to run in families — if a parent or sibling has scoliosis, your risk is higher.

The remaining cases have a clear cause: a birth defect that affects how the spine formed, an injury or infection that damaged the spine, a neurological condition like cerebral palsy or muscular dystrophy, or a bone disease like osteoporosis. Some people develop scoliosis later in life from wear and tear on the spine, a condition called degenerative scoliosis.

Key Takeaways

  • Most scoliosis (about 80 percent) has no known cause and develops during childhood growth years, particularly between ages 10 and 18.
  • Scoliosis often runs in families, so having a parent or sibling with the condition increases your own risk.
  • Some scoliosis results from birth defects, injuries, infections, neurological conditions, or bone diseases that affect spine structure.
  • Degenerative scoliosis can develop in adults as the spine ages and the discs and joints wear down over time.
  • Factors like poor posture, carrying heavy backpacks, or exercise do not cause scoliosis to develop.

Idiopathic scoliosis and growth

When scoliosis develops without a known cause, growth plays a central role. During the teenage years, the spine grows rapidly, and in some people, the vertebrae (the small bones that make up the spine) grow unevenly. One side of a vertebra may grow faster than the other, causing the spine to curve sideways instead of staying straight.

This uneven growth happens in people whose bodies are genetically predisposed to it, though scientists do not yet fully understand the exact mechanism. The curve typically worsens during the growth spurt and then stabilizes once growth stops in early adulthood. This is why scoliosis is most often diagnosed in children and teenagers — the condition becomes visible as the body grows.

Girls are more likely to develop curves severe enough to need treatment, though boys and girls develop idiopathic scoliosis at roughly equal rates. The reason for this difference is not fully understood.

Scoliosis from birth defects

Some babies are born with vertebrae that did not form correctly. In congenital scoliosis, one or more vertebrae may be partially formed, fused together, or shaped abnormally. These structural problems cause the spine to curve from birth or early childhood.

Congenital scoliosis is relatively rare and often detected during infancy or early childhood through imaging. It may be associated with other birth defects affecting the heart, kidneys, or limbs. Because the abnormal vertebrae continue to grow unevenly, congenital scoliosis tends to progress more predictably than idiopathic scoliosis, and treatment is often recommended earlier.

Scoliosis from neurological and muscular conditions

Conditions that affect the nerves or muscles can lead to scoliosis because the muscles that support the spine become weak or unbalanced. Neuromuscular scoliosis develops in people with cerebral palsy, muscular dystrophy, spina bifida, or other conditions that impair muscle control or strength.

In these cases, the spine curves because the weakened muscles cannot hold it upright against gravity. The curve often develops earlier and progresses faster than idiopathic scoliosis. People with severe neuromuscular scoliosis may face challenges with breathing, sitting, or organ function, which is why monitoring and treatment are often more urgent.

Scoliosis from injury, infection, and bone disease

Trauma to the spine — from a car accident, fall, or sports injury — can damage the vertebrae or the discs between them, leading to scoliosis. Similarly, a serious spinal infection can weaken the bone structure and cause the spine to curve as it heals.

Bone diseases like osteoporosis, which makes bones brittle and prone to fracture, can also result in scoliosis. When osteoporosis causes vertebrae to collapse or fracture, the spine may curve. This type of scoliosis typically appears in older adults and is sometimes called degenerative scoliosis when it develops from age-related wear and tear on the spine.

Degenerative scoliosis in adults

As the spine ages, the discs between the vertebrae lose water and become less flexible, and the joints wear down. This normal aging process can cause the spine to shift and curve, particularly if one side wears faster than the other. Degenerative scoliosis usually develops after age 50 and may cause back pain, stiffness, or nerve symptoms.

Degenerative scoliosis is different from idiopathic scoliosis because it develops from mechanical wear rather than growth problems or structural defects. It is more common in people with a history of back problems, previous spine surgery, or osteoporosis.

What does not cause scoliosis

Several common beliefs about scoliosis causes are not supported by evidence. Poor posture does not cause scoliosis, though it may make an existing curve more noticeable. Carrying a heavy backpack, playing sports, or being physically active does not cause the condition to develop. Calcium deficiency or vitamin D deficiency in childhood does not cause idiopathic scoliosis, though these deficiencies can weaken bones in other ways.

Scoliosis is not contagious and cannot be caught from another person. It is also not caused by sleeping position, mattress type, or any injury during childhood play.

Frequently Asked Questions

Can scoliosis be inherited?

Scoliosis often runs in families, particularly idiopathic scoliosis. If a parent or sibling has scoliosis, your risk of developing it is higher. However, inheriting the genetic predisposition does not may provide you will develop scoliosis — some family members may never develop a curve.

Can scoliosis develop suddenly in an adult?

Idiopathic scoliosis does not suddenly appear in adults; it develops during childhood and teenage years. However, degenerative scoliosis can develop or become noticeable in adults as the spine ages. If you notice a new curve as an adult, see a doctor to determine whether it is degenerative scoliosis or another spine condition.

Does exercise cause scoliosis to develop?

No. Exercise and sports do not cause scoliosis. In fact, staying active is generally recommended for people with scoliosis. Some high-impact activities may cause discomfort if a curve is severe, but they do not cause the curve to form in the first place.

Can scoliosis be prevented?

There is no way to prevent idiopathic scoliosis because the cause is not yet fully understood. If scoliosis runs in your family, regular screening during childhood and teenage years can catch a curve early, which may affect treatment options. Congenital scoliosis cannot be prevented, but early detection allows doctors to monitor and manage it.