Scoliosis: Causes, Diagnosis & Treatment Options

Scoliosis is a sideways curvature of the spine. Seen from behind, a healthy spine runs straight down the middle of the back; in scoliosis it bends to one side in a “C” or “S” shape, and the vertebrae also rotate slightly. A curve is only called scoliosis once it measures at least ten degrees on an X-ray — smaller deviations are within the normal range.

What is scoliosis?

The word describes a structural change in the shape of the spine, not simply poor posture. Because the bones are rotated as well as tilted, the change cannot be corrected just by standing up straight. Scoliosis is common — most curves are mild, cause no symptoms, and are discovered by chance during a school screening, a routine examination, or an X-ray taken for another reason.

What matters clinically is not only the size of the curve today but whether it is likely to get worse. That depends largely on how much growing a person has left to do, which is why curves found in children and adolescents are followed more closely than the same curve in an adult.

Which parts of the spine are affected?

Scoliosis is described by where the main curve sits:

• Thoracic curves involve the upper and mid-back, where the ribs attach. Larger thoracic curves are the ones most likely to produce a visible rib hump.
• Lumbar curves involve the lower back.
• Thoracolumbar curves sit at the junction of the two, and combined curves produce the “S” shape, where one curve partly balances the other.

The location influences both how the curve looks and how it is treated.

Types of scoliosis

• Idiopathic scoliosis is by far the most common type and has no single identifiable cause. It is grouped by the age at which it appears: infantile, juvenile, and — most commonly — adolescent idiopathic scoliosis, which emerges around the growth spurt of puberty.
• Congenital scoliosis is present from birth, caused by vertebrae that did not form normally in the womb.
• Neuromuscular scoliosis develops alongside conditions that affect the nerves or muscles, such as cerebral palsy or muscular dystrophy.
• Degenerative (adult) scoliosis appears later in life as the discs and joints of the spine wear, allowing the spine to tilt.

Causes and risk factors

For adolescent idiopathic scoliosis — the type most people mean by “scoliosis” — there is no known single cause, although it tends to run in families. It is not caused by heavy school bags, sleeping position, or sporting activity. The strongest predictors of a curve getting worse are a larger curve at diagnosis, being female, and having a lot of growth remaining.

The other types each have their own basis: an abnormality of bone formation in congenital scoliosis, an underlying neuromuscular condition, or age-related wear in degenerative scoliosis.

Symptoms and warning signs

Many curves cause no symptoms and are noticed only as a change in appearance — uneven shoulders, a more prominent shoulder blade or hip, or a waistline that looks asymmetric. When the person bends forward, a curve often shows as a one-sided “rib hump.”

Certain features deserve prompt assessment rather than watchful waiting:

• A curve that is visibly and rapidly worsening
• Back pain that is persistent, severe, or wakes the person at night
• Pain, numbness, weakness, or changes in bladder or bowel control — symptoms that point to nerve involvement and should be reviewed without delay

How scoliosis is diagnosed

Diagnosis begins with a physical examination, including the forward-bend test, which makes a rotational rib hump easier to see. If scoliosis is suspected, a standing X-ray of the whole spine confirms it and allows the curve to be measured as a Cobb angle — the standard measurement used to grade severity and to track change over time.

Where more detail is needed, low-dose biplanar imaging (such as EOS) can produce a full-length image with less radiation, and MRI or CT may be used to look at the spinal cord and the detailed bony anatomy — for example before surgery, in very young children, or when the pattern is unusual.

Non-surgical treatment

Most people with scoliosis never need an operation. The options, considered first, are:

• Observation. Small curves, and curves in people who have finished growing, are commonly monitored with periodic examination and occasional X-rays to confirm they remain stable.
• Bracing. For a moderate curve in a child who is still growing, a well-fitted brace worn as prescribed aims to stop the curve worsening through the remaining growth. Bracing does not straighten a curve that is already present.
• Physiotherapy and conditioning. Scoliosis-specific exercises and general core and postural work can help comfort, function and confidence, and are often combined with the above.

When surgery is considered

Surgery is reserved for a minority of curves — typically those that are large, that keep progressing despite skeletal maturity or bracing, or that are causing significant deformity, imbalance, or nerve symptoms. The most common operation realigns and stabilises the spine with instrumentation and fusion; in growing children, growth-friendly techniques aim to control a curve while allowing the spine and chest to keep developing.

The aim of surgery is to correct and balance the spine safely and to prevent further progression — not to deliver a guaranteed cosmetic result. The right approach depends on the curve, the person’s age and growth, and their overall health, and is decided together.

Recovery and outlook

Outlook varies widely with the type and severity of the curve. Many people with mild scoliosis live entirely normally with no treatment beyond occasional review. For those who are braced or operated on, modern care allows most to return to a full and active life, though recovery timelines differ between individuals and procedures. Honest, individualised counselling — about both benefits and risks — matters more than any single statistic.

When to see a spine specialist

It is reasonable to seek a specialist opinion if a curve is visibly progressing, if a child in the growing years is found to have scoliosis, or if scoliosis is accompanied by significant or worsening pain. Any sign of nerve involvement — leg weakness, numbness, or a change in bladder or bowel function — warrants prompt assessment.