Complete Guide to Scoliosis: Types, Causes, and Treatment

Scoliosis is an orthopaedic spinal deformity involving a lateral (sideways) curvature of the spine that’s greater than 10 degrees (1, 2). It also frequently involves abnormal rotation of the vertebrae in the spine, resulting in a 3-dimensional deformity (1, 2, 3). In other words, people with scoliosis have a twist that causes their spine to be bent sideways, bent forward, and rotated all at the same time. Often a spine with scoliosis will look “S” or “C” shaped from the back. 

Scoliosis affects anywhere from less than 1% to over 15% of people, depending on the classification of scoliosis and what parameters are used to identify it (1). For example, the prevalence of idiopathic scoliosis in adolescents is 2-3% (1, 2). On the other hand, the prevalence of degenerative scoliosis in adults is 10% (4).

Anatomy of the Spine

To understand how the spinal column twists in cases of scoliosis, it’s critical to first understand some basic anatomy of the spine.

Vertebrae

The spinal column is composed of several small bones called vertebrae, which provide stability and protect the spinal cord. There are seven vertebrae in the cervical spine (neck), twelve in the thoracic spine (upper back), and five in the lumbar spine (lower back).

Below the lumbar vertebrae, you also have your sacrum (which forms part of your pelvis) and your coccyx (your tailbone). Each of these bones are actually made of four or five fused vertebrae, to provide additional stability for the nerves in the spinal canal. So in total, your body has thirty-three vertebrae.‍

Intervertebral Discs

In between each pair of adjacent vertebrae from the neck to the lower back, there’s a soft jelly-like disc which acts as a shock absorber for your spine. The discs also allow for greater mobility, as your vertebrae pivots off the discs above and below them.

Normal Spinal Curves

A healthy spine has gentle curves in its structure that enables it to better absorb shocks. You can see these curves if you look at someone from their side.

• In the neck and lower back, there’s a small inward curve towards the front called lordosis.
• In the upper back, there’s a small outward curve towards the back called kyphosis.
• When viewed from the back, there should be no curves to the left or to the right - the spinal column should appear straight.‍

Abnormal Curves in Scoliosis

In a spine with scoliosis, several vertebrae take a sideways or rotated position, resulting in an abnormal curvature.

The two common curve patterns in scoliosis are a “C” shaped curve and an “S” shaped curve.

These curves can occur in the thoracic (upper back) region, lumbar (lower back) region, or at the thoracolumbar junction (the meeting point of the upper and lower back).

Structural vs. Non-Structural Scoliosis

Scoliosis curves can either be structural or non-structural, depending on the root cause.

A structural curve is inflexible and doesn’t reverse when you bend in the opposite direction of the curve (3). For example, if you have a spinal curvature that’s angled towards the right, and it doesn’t disappear when you bend to the left, you have a structural scoliosis curve. 

Another sign of structural scoliosis is a visibly abnormal hump that can be seen when you bend forward. This hump results from the increase in curvature upon bending forward (5). 

Structural scoliosis curves are usually greater than 25 degrees, and are associated with a deeper pathology within the spine (5, 6). 

On the other hand, non-structural scoliosis curves are flexible, usually less than 25 degrees, and will reverse when you bend in the opposite direction (5).

Common causes of non-structural scoliosis include muscle spasms due to spinal injuries as well as leg length discrepancies (6). Treating these root causes usually completely resolves non-structural scoliosis.

Scoliosis has several possible causes and affects people of all age groups. To help understand the condition, the medical community has developed multiple classification methodologies for categorizing forms of scoliosis. Here, we’ll touch on a few of these methodologies.

Causes

One way to classify scoliosis is by root cause. These causes include:

• Congenital scoliosis (birth defect due to failure of the vertebrae to form properly in the womb) (2)
• Neuromuscular causes (neurological or muscular condition causing the spinal deformity, such as cerebral palsy, muscular dystrophy, or spina bifida) (2, 7)
• Connective tissue disorders (disorders of ligaments, muscles, and other tissues that connect bones and support organs, such as Marfan syndrome or Ehlers-Danlos syndrome) (2)
• Spinal degenerative changes associated with age (4)
• Idiopathic cases (cause is unknown and can’t be identified) (2)

Of these types, idiopathic scoliosis is the most common type of scoliosis (2). It is diagnosed when a healthcare provider rules out every other possible cause of scoliosis (5).

Age

Scoliosis can also be classified by age of onset. This classification is most relevant in cases of idiopathic scoliosis, and it can also be helpful when diagnosing scoliosis in adults. Below are the common age categories for scoliosis:

• Infantile Scoliosis: Scoliosis that develops before the age of 3 (2, 5).
• Juvenile Scoliosis: Scoliosis that develops between age 3 and 9 (2, 5).
• Early Onset Scoliosis: A newer classification of scoliosis groups infantile and juvenile scoliosis into “Early Onset Scoliosis” since children who develop scoliosis before they turn 10 generally require more involved care than those who develop it after turning 10 (8).
• Adolescent Idiopathic Scoliosis: Scoliosis that develops between age 10 and age 18 (9).
• Adult idiopathic scoliosis: Scoliosis that’s present in adults who were previously diagnosed with adolescent idiopathic scoliosis.
• Adult onset degenerative (de novo) scoliosis: Scoliosis that develops for the first time after the age of 50 (4). Adults who were previously diagnosed with scoliosis in childhood do not fall into this category‍

Other Classification Systems

Several other classification systems further divide scoliosis into additional subgroups and help quantify the severity of the scoliosis. These systems are based on the region of the spine in which scoliosis has developed as well as a measurement of the spinal curvature called the Cobb angle (5). Some of the more commonly used such systems are:

• King-Moe
• Lenke
• Coonrad
• Schwab
• Aebi
  

The two most common types of scoliosis by far are adolescent idiopathic scoliosis and adult degenerative scoliosis (3).

Adolescent Idiopathic Scoliosis (AIS)

As the name implies, AIS is scoliosis with an unknown cause that develops during adolescence. Signs and symptoms of AIS include:

• A noticeable hump in rib cage or lumbar spine in standing (9). Thoracic curves are more common in AIS, so the rib hump is more common than the lumbar hump (3).
• A slouch to one side (3).
• Ill-fitting shirts (3).
• Back pain. While some research reports that pain is not a typical symptom of AIS (3), newer studies suggest that back pain among adolescents is more common in those with AIS (10, 11). Recent research also indicates that back pain due to idiopathic scoliosis is clinically different back pain due to other sources. (12).

Most of the time, adolescents diagnosed with idiopathic scoliosis continue to demonstrate a scoliotic curve of some degree in adulthood.

Adult Degenerative Scoliosis

Adult degenerative scoliosis (ADS) differs from adult idiopathic scoliosis in that it develops after adolescence. If you’re over the age of 50 who’s recently been diagnosed with scoliosis, chances are it’s a case of ADS.

ADS results from asymmetric age-related degeneration of the spine, most commonly in the lumbar region (3). Examples of degenerative changes that contribute to curve development include:

• Spinal disc degeneration
• Degeneration of facet joints (the joints in between pairs of adjacent vertebrae)
• Degenerative spondylolisthesis (forward slippage of one vertebra)
• Lateral (sideways) vertebral movement greater than 6 millimeters (3, 4)

Family history and osteoporosis are also risk factors in ADS development (3, 4). Common symptoms associated with ADS include:

• Low back pain
• Radiculopathy (numbness, tingling, or burning sensation down one or both legs)
• Intermittent claudication (cramping or symptoms of muscle weakness in one or both legs) when in standing (3, 4)

These scoliosis symptoms also happen to be symptoms of spinal stenosis, a condition characterized by decreased space in the spinal canal or in nerve root exits from the spinal column. Newer research has revealed that up to 90% of adults with ADS also have spinal stenosis, particularly on the concave (inner) side of the scoliotic curve (3, 13, 14). 

This means that if you’ve been diagnosed with scoliosis as an adult, you are also at a higher risk of developing spinal stenosis, which can compound your symptoms. 

Simultaneously developing scoliosis and spinal stenosis tends to result in rather severe symptoms and can significantly impact quality of life, including creating difficulty with basic tasks like standing or walking (4, 14).

Typically the main treatment goals for scoliosis are the prevention of curve progression and the reduction of any back pain, in order to maximize mobility and independence (1, 2). 

While treatment is generally insufficient to completely correct the spinal column, it’s nevertheless important as failure to treat can worsen the spinal curvature and result in a host of secondary problems, such as: 

• Decreased pulmonary (lung) capacity
• Increased cosmetic deformity
• Increased pain
• Decreased function and quality of life (15)

While the exact implementation of the treatment plan will vary from case to case, each of the following care components in this section typically plays a role in the treatment.

Observation

If your curve is less than 25 degrees, and you are not experiencing any associated back pain, the first step is often to monitor the curve over a period of several months. Your doctor will likely conduct physical exams and order X-ray or CT imaging every 3-6 months to check that the curve is not progressing (1, 2).

Bracing

If your curve is somewhere between 25 and 50 degrees, bracing can be a good way to prevent curve progression. Research to date focuses on the use of bracing in cases of adolescent idiopathic scoliosis. New studies also support the use of bracing in cases of adult idiopathic scoliosis and adult degenerative scoliosis (16).

Compliance is key for unlocking the benefits of bracing. Unfortunately, braces are often cumbersome and uncomfortable, which can reduce motivation for regular use (to the tune of at least a few hours per day) and consequently limit the long-term benefits of bracing (2, 16).

Surgery

Spinal fusion is generally considered in cases of AIS in which the curve exceeds 45 degrees or shows rapid progression. This type of surgery uses metal rods and bone grafts to fuse the vertebrae, thereby limiting curve progression and improving spinal balance (2, 3).

By contrast, in cases of ADS, the goal of surgery is to reduce pain. Complete fusion (long segment fusion), similar to fusion surgery for AIS, is one possible procedure. There are also a handful of other surgical options for ADS, including a simple spinal decompression procedure (in which part of a vertebra is removed to relieve nerve pressure) and short segment fusion (3).

All surgical options come with potential side effects and complications. In particular, scoliosis surgeries, especially in adults, involve trade-offs between pain reduction and curvature reduction:

• Spinal decompression - While this procedure is effective for alleviating radiculopathy and claudication symptoms, it’s also associated with more rapid progression of scoliosis deformity and spinal stenosis (3).
• Fusion (short and long) - While fusion is more effective at stabilizing the curve and alleviating nerve compression, accelerated degeneration in vertebrae that are not fused can result in the recurrence of back pain (3).‍

Additional Treatment Options

In addition to observation, bracing, and specialized surgical procedures, several medications and injections can offer relief from pain due to scoliosis. These include: 

• Anti-inflammatory drugs (NSAIDs).
• Steroid injections (specifically for radiculopathy symptoms) (3).
• Medical cement injections: These are used specifically for those who have both degenerative scoliosis and osteoporosis, in order to decrease pain following an osteoporotic fracture. Research shows that cement injections in vertebrae can rapidly reduce pain (17).
  

Research on exercise as a treatment for scoliosis is sparse, particularly when it comes to adult scoliosis (18). As a result, the medical community disagrees on whether exercise should be included in courses of treatment for scoliosis (15). 

Some research on stabilization exercises has found that exercise can be helpful in reducing back pain and disability in patients with adult idiopathic scoliosis (18). Preliminary evidence also indicates that exercise helps to delay curve progression in adolescent idiopathic scoliosis (1, 19). However, the studies agree that further research and additional higher level clinical trials need to be completed in order to confirm initial findings. 

In just the last five years, several lower level studies have been published on scoliosis-specific exercises (SSEs). Many provide evidence that SSEs are beneficial in preventing curve progression and limiting brace prescription in adolescent and adult idiopathic scoliosis (15, 19, 20, 21). This is especially true in cases of mild curvature. Additionally, SSEs appear more effective than general physical therapy exercises (15, 19).

Several different programs of SSEs have been developed, and physical therapists require specific training in order to be able to properly incorporate them into clinical practice. Programs that have been studied in detail include:

• SEAS (Scientific Exercise Approach to Scoliosis) (15, 19)
• Schroth (15, 20)

In my own clinical practice, I have seen exercise successfully reduce back pain for adults with both idiopathic scoliosis and degenerative scoliosis. Some exercises I typically incorporate are hamstring stretches, piriformis stretches, bird dogs, and dead bugs.

If you have scoliosis and you’re worried about its impact on your life, remember that you have several possible treatment paths, including multiple non-surgical options.

If your curve is still mild and your pain is minimal, then now is a good time to find a physical therapist with scoliosis-specific training to get your pain under control and work on delaying curve progression.  

If your curve is moderate or you’re having more significant pain, conservative measures such as exercise, bracing, and anti-inflammatory pain medications can still delay curve progression and alleviate your symptoms. 

Even if you have a particularly severe case of scoliosis and your doctor ultimately recommends surgery, make sure to ask what all the surgical options are, so that you and your doctor can decide which one will likely be the most successful for your situation.