What causes scoliosis

Most people with scoliosis are born with a spine that curves sideways, and doctors do not know why this happens. The curve develops during childhood or the teenage years as bones grow. In some cases, scoliosis runs in families — if your parent or sibling has it, your risk is higher — but inheriting the gene does not may provide you will develop it.

A smaller number of people develop scoliosis later in life because of a specific cause: a spine injury, muscle weakness from a neurological condition, or degenerative changes in the spine as it ages. Understanding which type you or a family member has matters because the treatment path differs.

Key Takeaways

  • Most scoliosis (called idiopathic scoliosis) has no known cause and develops during growth years in children and teenagers.
  • Scoliosis can run in families, but having a family history does not mean you will definitely develop the condition.
  • Some people develop scoliosis because of spinal injury, neuromuscular conditions, or age-related spine changes.
  • Doctors identify the type of scoliosis by examining the spine and taking X-rays to measure the curve.
  • Early detection during childhood screening can help track whether a curve is likely to worsen as the child grows.

Idiopathic scoliosis — the most common type

About 80 percent of people with scoliosis have what doctors call idiopathic scoliosis, which means the cause is unknown. The curve appears during the growth years — most often between ages 10 and 18 — and tends to progress faster when a child is growing quickly. Girls are more likely than boys to develop curves severe enough to need treatment.

Researchers have found that idiopathic scoliosis sometimes runs in families, suggesting a genetic component, but no single gene has been identified. Having a parent or sibling with scoliosis increases your risk, but many people with a family history never develop the condition. The curve itself is not caused by poor posture, carrying heavy backpacks, or sports — these are common myths.

Idiopathic scoliosis is usually discovered during a school screening, a routine physical exam, or when a parent or child notices an uneven shoulder or waistline. Once found, doctors track the curve with X-rays to see whether it is stable or worsening.

Neuromuscular scoliosis — linked to muscle and nerve conditions

Neuromuscular scoliosis develops when a condition affecting muscles or nerves weakens the spine's support system. Cerebral palsy, muscular dystrophy, spina bifida, and spinal cord injury are common causes. Because these conditions affect muscle tone and control, the spine cannot hold itself upright properly, and a curve develops.

Neuromuscular scoliosis often appears earlier and progresses faster than idiopathic scoliosis. Children with these underlying conditions are usually monitored closely by their doctors, and scoliosis screening is part of routine care. Treatment decisions depend on the severity of the curve and how much it affects breathing or sitting balance.

Congenital scoliosis — present from birth

Congenital scoliosis means the spine did not form normally before birth. The vertebrae may be wedge-shaped, fused together, or missing parts. This type is rare and is usually detected in infancy or early childhood, sometimes on imaging done for other reasons.

Congenital scoliosis does not always progress, but some curves worsen as the child grows. Doctors monitor these curves carefully with regular X-rays. Treatment depends on the specific vertebral abnormality and how fast the curve is advancing.

Degenerative scoliosis — developing later in life

Degenerative scoliosis develops in adults, usually after age 50, when the discs and joints in the spine wear down over time. As the spine loses flexibility and stability, a sideways curve can develop. This type is sometimes called adult-onset scoliosis.

Degenerative scoliosis is often painless, but some people experience back pain or leg pain if the curve pinches nerves. It tends to progress slowly. Imaging such as X-rays or MRI may be ordered if symptoms develop or if the curve appears to be worsening.

Scoliosis from injury or disease

A serious spine injury — from a car accident, fall, or sports injury — can damage vertebrae in a way that causes or worsens a curve. Similarly, infections of the spine, tumors, or osteoporosis can weaken the spine structure and lead to scoliosis.

This type of scoliosis is usually identified after the injury or illness is diagnosed. Treatment focuses on both the underlying cause and managing the curve itself.

How doctors determine the cause

Your doctor will start with a physical exam, looking at your spine from the front and back and checking whether your shoulders or hips are level. You will be asked about your medical history, whether scoliosis runs in your family, and when the curve was first noticed.

An X-ray is the standard tool for confirming scoliosis and measuring the curve. The doctor measures the angle of the curve in degrees — a curve of 10 degrees or less is considered mild, while curves of 50 degrees or more are considered severe. If the doctor suspects an underlying condition like neuromuscular disease, additional imaging or tests may be ordered.

Frequently Asked Questions

Can you develop scoliosis from bad posture?

No. Poor posture does not cause scoliosis, though it may make an existing curve more noticeable. Scoliosis is a structural curve in the spine itself, not a postural habit. However, good posture can help reduce back strain if you already have scoliosis.

If my parent has scoliosis, will I definitely get it?

No. While scoliosis can run in families, having a parent with the condition does not may provide you will develop it. Your risk is higher than average, but many people with a family history never develop scoliosis. Regular screening during childhood and teenage years can catch a curve early if one does develop.

Can adults develop scoliosis for the first time?

Yes. Degenerative scoliosis can develop in adults as the spine ages and discs wear down. Scoliosis can also develop after a spine injury or as a result of conditions like osteoporosis. This is different from idiopathic scoliosis, which develops during childhood growth.

Does scoliosis always get worse?

Not always. Many curves remain stable and do not progress. Curves that develop during childhood are more likely to worsen during the growth years, especially in girls and in curves larger than 25 degrees. Adult curves typically progress slowly, if at all. Your doctor will monitor your curve with X-rays to track any changes.

What is the difference between idiopathic and neuromuscular scoliosis?

Idiopathic scoliosis has no known cause and usually develops during teenage years. Neuromuscular scoliosis is caused by a condition affecting muscles or nerves, such as cerebral palsy or muscular dystrophy, and often appears earlier and progresses faster. Treatment approaches differ based on the underlying cause.