What Is Scoliosis?

What Is Scoliosis?

There are two main criteria that will lead to a scoliosis diagnosis. The spine needs both a bend of greater than 10 degrees, along with a related degree of rotation. Scoliosis is only diagnosed when both are present, not just one or the other alone. 

Before one can grasp the idea of what scoliosis is, there needs to be a discussion about what it isn’t, by first covering the main differences between a postural issue, and true scoliosis. By establishing the basics of the anatomy of the spine, it will become clear what curves are healthy, and what words like kyphosis or lordosis mean.

The healthy spine, viewed from the side, should look like a muted “S” shape, as if you took the letter “S” and stretched it out a bit. When these healthy curves are outside of normal ranges, the body tries to regain them on its own, sometimes making bad curves.

The three normal curves that a healthy spine will display, from top to bottom, include a cervical, thoracic and lumbar curve.

  • The cervical curve should be located within the upper back and neck, curving inward, like the letter “c”, with the open end facing backward.
  • The thoracic curve should be located in the middle back, with an outward curve, like a reversed letter “ↄ” with the open end facing forward.
  • The lumbar curve should be located in the lower back with an inward curve, again like the letter “c”, with the open end facing backward.

Why does the spine need these curves from the side? Put simply, these curves make the spine more resilient. Spinal curves allow the spine to take impacts and forces, and distribute them evenly, so that long repetitive or short impact pressures don’t cause as much localized damage. This is important considering the spine’s precious cargo, the spinal cord (a long fragile bundle of nerves that carry information from the brain to the rest of the body). Typically, scoliosis sees a loss of these healthy curves, leading to the development of abnormal curves. Some terms often used to describe these unnatural curves are “kyphosis” and “lordosis”, but these terms define more than just unnatural curves. These terms can be used to define a healthy spinal curve too!

In a healthy spine, kyphosis refers to the normal outward curve of the spine, which is mostly in the thoracic region. In an abnormal spine, kyphosis can be used to refer to an overly curved upper back, clinically known as “Hyperkyphosis”.

In a healthy spine, lordosis refers to the natural inward curves of both the cervical and lumbar regions. In an abnormal spine, lordosis may refer to the abnormal extreme curvature of the lower back inward, clinically known as “hyperlordosis”.

Because these can be confusing terminologies, especially since these terms are used interchangeably, but with vastly different meanings, a graphic below explains the definitions in varying cases:

Whenever the spine curves outside of normal ranges, these terms are used to refer to the abnormal curving. 

This is very similar to how your doctor may word information about your blood pressure:

  • hypertension means the blood pressure is above normal values (high bp) and
  • hypotension means the blood pressure is below normal ranges (low bp).

Similarly, there is normal kyphosis (in the thoracic), hyperkyphosis (too much outward curve), and hypokyphosis (too little outward curve). The terms are only used for reverse curves when a curve has been lost to the degree that it now curves the opposite direction, such as if the neck, which should curve inward, curves outward.


As discussed, scoliosis has two, specific characteristics that must be co-existing for a scoliosis diagnosis. These include a sideways spinal curvature of at least 10 degrees, accompanied by rotation of some kind.

Does Curve Size Matter?

For a diagnosis of scoliosis, a lateral curve must be present with a measured angle of 10 degrees or greater. Today, this measurement is taken by using software, on patient X-rays, to measure the angles between vertebrae, using the most tilted vertebrae as an apex of the angle, a measure known as the “Cobb angle”. This measurement shows the practitioner how much the abnormal curve diverges from healthy, straight alignment down the back. Mild scoliosis is 10-25 degrees from normal, moderate scoliosis is 25-45 degrees curvature, and a deviation of greater than 45 degrees is considered severe.

Interestingly, the direction of the curve is very telling to the underlying cause of the scoliosis. Curves to the right in the thoracic region (when looking from behind), may have a variety of structural, lifestyle, or injury related origins, and will often be treated freely. Curves to the left in the thoracic region are less common, as the left side of that part of the body, houses the heart. When scoliosis is accompanied by left-sided curves in the thoracic region, there is likely an underlying medical cause, such as congenital defects, neurological dysfunction or tumors present, leading practitioners to be cautious. However, curves to the left in the lumbar region are very common and typical, not indicative of any underlying pathology.

What About Rotation?

While the size of the curve is important for defining scoliosis, rotation must also be present. In fact, many experts regarding scoliosis believe rotation may be the initial factor involved in developing a scoliotic curve.

The second, and equally important characteristic of a scoliotic spine is the rotation spinal curve. The 10 degree bend of the spine is not enough for a scoliosis diagnosis. Rather, this bend must coexist with a rotation, giving scoliosis a 3-D nature, making it a 3-D condition.

This is because the presence of both 10 degree lateral bending, and rotation, rules out the possibility of bad posture being to blame. Both characteristics existing in the same person, at the same time, means the patient more than likely has scoliosis, not just a scoliotic curve.

One way to confirm this diagnosis, and rule out postural problems, can be for practitioners to perform bending X-rays to see if the curve is still present when the patient bends laterally. If some of the curvature remains through the bend on each side, or the patient bends in an asymmetrical way, then bad posture or position are not to blame. Rather, a structural deformity has occurred, caused by scoliotic curve development.

Postural problems rarely have rotation, so when bending curves occur without rotation, it is something called a “postural” scoliosis, as true scoliosis will show rotation.


After a diagnosis of scoliosis, practitioners will put together a treatment plan for counteracting the structural deformities. This makes it vital to distinguish between “postural scoliosis” and true scoliosis, as true scoliosis will not respond well to treatments aimed at fixing injury-related or posture-related problems. True scoliosis needs more than just adjustments, stretching or muscle strengthening, although these may be a part scoliosis treatment plan. These structural deformities of scoliosis need to be treated for effective relief in scoliosis patients, because their pain is not based on simple misalignment or injury.

Some patients, especially those with milder cases, may not want to make major changes, to correct what seems, to them, like minor deformity. What needs to be emphasized is that no matter where the scoliosis develops, due to the unified biomechanics of the spine, the whole back will be thrown off its natural function, disturbing the biomechanics of the entire skeletal system. No matter how small the issue may seem at the time, left untreated, scoliotic curves and rotation will almost always worsen, making early treatment vital for long-term relief.

How is Progression Managed?

There are always individual variables that will impact the rate that scoliosis develops, however, there are two general progression patterns that everyone will follow.

  • Before skeletal maturity (ie. in adolescents), scoliosis will progress more quickly, as growth can trigger the progression of scoliotic curves and rotations.
  • After skeletal maturation (ie. in adults), scoliosis will progress more slowly, as the bones are no longer growing. Therefore the cause of progression is the load of gravity on an asymmetrical spine or changing shape & size.

Before treatment begins, it is important that patients understand that scoliosis is a progressive condition with no cure. This means that patients will spend a lifetime treating the condition if they want to actually slow progression and have relief. This makes choosing the right treatment plan vital, as it shapes how the patient will experience this disease for the rest of their lives.

The most effective and long-lasting treatments involve addressing the structural disorder, not just the discomfort or symptoms. This means looking at the patient holistically by considering age and the location, severity & type of the curvature.

Once this has been discovered via X-ray, a treatment plan can be customized to address the condition using exercises, physical therapy, scoliosis-specific chiropractic adjustments, rehab, and, in some cases, corrective bracing. By manipulating the scoliosis externally, these treatments are aimed at restoring the natural and healthy curve of the spine, which improves its biomechanics, and therefore its function.


Whenever a patient is concerned about a bend or curve in their spine being scoliosis, it may be reassuring to know that scoliosis is much more than simply a curve. Curves in the spine can be the result of bad posture, whereas scoliosis, which is a curvature accompanied by rotation, is a structural deformity.

This distinction is important, as no matter how a patient with scoliosis stands, sits, lays or bends, the scoliosis will always be present. On top of that, patients with true scoliosis will likely see the disease progress, whether quickly or slowly, with more rotation and curvature as time goes on.

This means that treating or counteracting scoliosis effectively must be done by addressing the structural deformity and reducing the curve.