What Causes Scoliosis?
A Closer Look at the Underlying Pathology in Children and Adults
Medically reviewed by Josephine Hessert, DO
Scoliosis is an abnormal curvature of the spine of 10 degrees or more. It affects about 2% to 4% of the global population. While it usually develops in childhood or adolescence, it can occur in adulthood.
It can be idiopathic (unknown cause), congenital (from embryonic malformation), or neuromuscular (associated with neuromuscular conditions). In adults, it can be degenerative. More than 80% of scoliosis cases are idiopathic, with no known cause.
This article will discuss causes of scoliosis in children and adults, causes of secondary scoliosis, risk factors for scoliosis, and possible treatments for scoliosis.
What Causes Scoliosis in Children?
The three causation classifications of scoliosis in children and adolescents are:
Idiopathic
Congenital
Neuromuscular
Idiopathic Scoliosis
Idiopathic scoliosis is the most common type, representing about 80% of cases. It's not known what causes idiopathic scoliosis, but researchers believe it may involve several factors, including:
Genetics
Hormones
Changes in cell structure
About 30% of adolescents with idiopathic scoliosis have a family history of scoliosis.
Idiopathic scoliosis is most commonly developed in middle childhood and adolescence, typically between the ages of 10 and 15 years old. It is usually diagnosed during puberty, and a diagnosis is made when all other causes have been excluded.
Idiopathic scoliosis can't be prevented since it is not caused by factors such as poor posture, carrying a heavy backpack, diet, or exercise.
Growing can make idiopathic scoliosis worse, so more care needs to be taken in children who have a significant amount of growing left to do.
Congenital Scoliosis
Congenital scoliosis is present at birth and is typically detected earlier than idiopathic scoliosis, sometimes in infancy but often later in childhood.
The malformations of one or more vertebrae that lead to congenital scoliosis occur in the fetus before birth. This can occur anywhere on the spine and cause curvature or other problems because one area of the spinal column lengthens more slowly than the rest.
Children with congenital scoliosis are at an increased risk of having other congenital abnormalities, typically with the spinal cord, genitourinary tract (system of organs involved in urine production and secretion and reproduction) and/or the heart. When diagnosed with congenital scoliosis, they should have neurological, genitourinary, and cardiovascular evaluations.
Neuromuscular Scoliosis
Neuromuscular scoliosis occurs as a result of other medical conditions that affect the nerves and muscles, such as:
Spinal cord trauma
With neuromuscular conditions such as these, there can be an imbalance and weakness in the muscles that support the spine.
Neuromuscular scoliosis tends to progress more quickly than idiopathic scoliosis and may require surgery.
What Causes Scoliosis in Adults?
Adult scoliosis is a curve in the spine of at least 10 degrees in a person who is 18 years or older. It can be classified as:
Adult idiopathic scoliosis
Degenerative scoliosis (also called adult de novo scoliosis)
Adult Idiopathic Scoliosis
Adult idiopathic scoliosis begins in childhood or adolescence and continues into adulthood, typically with increasing symptoms. It affects the thoracic (upper) or lumbar (lower) spine.
Scoliosis may cause disks and joints in the spine to degenerate, which could lead to spinal stenosis (narrowing of the spinal canal). It can also cause arthritis in the spinal joints, which could result in bone spurs (bony growths).
The cause of adult idiopathic scoliosis is not known, but genetics is believed to be a factor.
Degenerative Scoliosis
Adult degenerative scoliosis occurs when there is wear-and-tear breakdown of the spinal disks and joints that causes twisting and shifting of the vertebrae. This degeneration can progress and cause the spine to become more unbalanced, and curve into a C-shape.
Degenerative scoliosis can cause back and leg pain, and the spinal imbalance that comes with it can make it painful to walk, stand up straight, or run.
It may also lead to spinal stenosis (narrowing of the spinal canal), causing compression of the nerves in the spine. This can lead to sciatica (shooting pain, heaviness, tingling, weakness, and numbness in the buttocks and legs).
Degenerative scoliosis is more common in the lower back, and the associated curvature of the spine is often relatively minor. Back pain from this type of scoliosis tends to develop gradually.
Factors that can contribute to the development of degenerative scoliosis include:
Age (it usually begins after age 40 years)
Spinal deterioration
Facet joint arthritis
Collapse of disk spaces
What Causes Secondary Scoliosis?
Scoliosis can occur as part of or as a result of another medical condition, including:
Genetic conditions
Injury to the spine
Tumor
Neuromuscular conditions
Some syndromic conditions associated with scoliosis include:
Other connective tissue disorders
Muscular dystrophy
Neurofibromatosis (NF)
Osteochondrodystrophy (dwarfism)
VATER/VACTERL syndrome
There is also a type of scoliosis called nonstructural, or functional, scoliosis. With this type of scoliosis, the spine appears curved but is actually normal. This can happen in situations such as:
A temporary injury of the spine
An infection of the spine
Having legs that are different lengths
When the underlying problem is resolved, so will the curve.
Do Causes and Risk Factors Differ by Degree of Scoliosis?
Congenital scoliosis has a higher likelihood of progressing in severity than other forms, and children often require surgery or other interventions to prevent complications.
Neuromuscular scoliosis tends to be associated with severe curves and can affect the entire length of the spine. The pelvis may also be tilted to one side (pelvic obliquity).
Factors That Increase Scoliosis Risk
Anyone can get scoliosis, and it may not be preventable, but there are some things that may make developing it more likely.
Factors that can increase the risk of idiopathic scoliosis include:
Age: It typically occurs in older children and adolescents.
Sex assigned at birth: People assigned female at birth are more likely to develop it than those assigned male at birth.
Family history: People who have a sibling or parent with scoliosis are more likely to develop it than those who do not.
Scoliosis In Girls and Women
Higher rates of scoliosis are found in people who were assigned female than male at birth. There is conflicting evidence about whether or not there is actually an imbalance in occurrence or just in diagnosis.
Research has found that people who were assigned female at birth are 8 times more likely to develop more severe curves and require treatment.
There is some evidence that regions on the X chromosome significantly contribute to a higher prevalence of adolescent idiopathic scoliosis in those who were assigned female at birth.
Degenerative scoliosis can be related to osteoporosis, which is more common in people assigned female at birth, especially those who have been through menopause.
Living With Scoliosis and Possible (Required) Treatments
Scoliosis treatment can differ depending on age.
Scoliosis Treatment for Children
Treatment is intended to stop the progression of the curve and prevent deformity.
Before determining treatment for a child who has a diagnosis of scoliosis, several factors need to be considered, including:
If the spine is still growing and changing
The severity of the curve
The location of the curve
How it affects the person's lifestyle
Likelihood of the curve progressing
Options for treatment include:
Observation: Also called a watch-and-wait approach, it involves repeated examinations to see if the spine continues to curve. Observation is used when the curve is less than 20 degrees and the child is still growing.
Bracing: An external torso brace is worn for a number of hours, applying corrective pressure to the spine as it grows. It is used for children who are still growing and have curves between 20 to 50 degrees,
Surgery: Surgery may be needed for severe scoliosis or a curve of more than 50 degrees.
Casting: A plaster cast is fitted around the back and cannot be removed. This is used for babies and toddlers as it may be easier to wear the cast than a removable back brace while very young. It is changed every few months.
Scoliosis Treatment For Adults
The first-line treatment for adult scoliosis is physical therapy, which can help develop proper back mechanics. This minimizes stress on the spine during exercise and activities that involve lifting or bending.
Other nonsurgical treatment options include:
Exercises aimed at strengthening back and core abdominal muscles
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as Advil or Motrin (ibuprofen), Aleve (naproxen), or aspirin
Epidurals or nerve block injections (can provide temporary relief of symptoms such as leg pain)
Surgery may be recommended if nonsurgical options are not effective and/or there is a spinal imbalance with debilitating back or leg pain. Surgical options may include:
Microdiscectomy (microdecompression): Minimally invasive surgery to treat a herniated disk and relieve pressure on the nerves
Laminectomy: Also called decompression surgery, removes some or all of the lamina (roof of the spinal canal) to relieve pressure on the spinal cord
Spinal fusion: Permanently joins two vertebrae so there is no longer movement between them
Osteotomy: A set of procedures that correct certain spinal deformities
Vertebral column resection: Complete removal of one or more vertebrae to realign the spine, used when other options have not worked
Summary
Scoliosis can develop at any age but most commonly develops in adolescence. The most common type of scoliosis is idiopathic. It isn't known what causes idiopathic scoliosis, but genetics, hormones, and changes in cell structure may be involved.
Scoliosis can also be congenital (problems with the spine developed in the womb), or neuromuscular (resulting from neuromuscular conditions). Adult scoliosis can be idiopathic or degenerative. Degenerative scoliosis is caused by wear-and-tear of the spinal disks and joints, which causes the spine to become unbalanced and curved.
Secondary scoliosis is a curvature of the spine that results from or is part of another medical condition. Nonstructural/functional scoliosis temporarily causes the spine to appear curved but resolves when the underlying cause is addressed.
Severe curvature with scoliosis is more common in people who were assigned female at birth. Treatment options for children with scoliosis include observation, bracing, surgery, or casting.
Treatment options for adults with scoliosis include physical therapy, targeted exercises, NSAIDs, epidurals or nerve block injections, temporary braces, or surgery.
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