Scoliosis is often described as a complex condition to treat because it can range widely in severity, but also because there are several different types of scoliosis a person can develop, based largely on etiology. Causation is a key factor because it explains a condition’s underlying cause and guides the design of effective treatment plans moving forward.
Not only does scoliosis develop across a wide severity spectrum, but there are also multiple condition types. Idiopathic scoliosis accounts for 80 percent of known diagnosed cases; the remaining 20 percent are classified as neuromuscular, congenital, degenerative, or traumatic.
When scoliosis is first diagnosed, it’s further classified based on a number of important patient/condition variables, including causation. Before moving on to etiology and the different types of scoliosis, let’s start by defining the condition in general terms.
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The spine is an essential structure of human anatomy. It allows us to stand upright, maintain a good posture, engage in flexible movement, absorb and distribute mechanical stress, and support the upper body's weight.
In addition, the spine works in tandem with the brain to form the body’s central nervous system (CNS), which facilitates brain-body communication and is involved in the function of virtually every working system within the body.
When a person is diagnosed with scoliosis, this means they have developed an unnatural sideways spinal curve, with rotation, and a minimum Cobb angle of 10 degrees.
In what’s considered a typical scoliosis, the curve would bend to the right, away from the heart. In atypical forms, a curve can bend to the left, towards the heart.
Not only does a scoliotic curve bend unnaturally to the side, but it also twists from front to back, back to front (rotational component).
A patient’s Cobb angle is measured during X-ray by drawing intersecting lines from the tops and bottoms of the most-tilted vertebrae at the apex of the curve.
Cobb angle is known as the orthopedic gold standard in scoliosis assessment because it indicates how far out of alignment a scoliotic spine is, and places a condition on its severity scale of mild, moderate, severe, and very severe.
Another key feature of scoliosis is its progressive nature: it’s in the nature of the structural condition to worsen over time, especially if left untreated, or not treated proactively.
While all types of scoliosis are progressive, the progressive rates can vary in the different types, which we’ll return to in more detail later.
There are a variety of factors that make different types of scoliosis unique, and now that we have defined the condition, let’s move on to how scoliosis is classified as part of the diagnostic/assessment process.
As mentioned, part of the diagnostic/assessment process involves further classifying a condition based on key patient and condition variables. These variables will shape a person’s experience of living with their condition and the types of symptoms it can produce.
In addition to patient age, condition severity, and curvature location, causation is a key classification point that determines condition type by explaining its underlying cause and informing the design of customized treatment plans.
So let’s talk about the most common type of scoliosis and work through the different forms from there.
Idiopathic scoliosis is the most common type of scoliosis, accounting for 80 percent of known diagnosed scoliosis cases.
Idiopathic means not clearly associated with a single clear causative source, and this is not the same as saying there is a complete absence of cause; instead, idiopathic scoliosis is considered multifactorial, meaning caused by multiple factors that can vary from one person to the next.
Under the umbrella of idiopathic scoliosis, there are different types: the most common being adolescent idiopathic scoliosis (AIS), and idiopathic scoliosis in adults.
Adolescent idiopathic scoliosis is the most prevalent form of the condition and is diagnosed between the ages of 10 and 18.
As this form is idiopathic in nature, its causation is not fully understood, but what we do understand is how to treat it moving forward and the condition’s number-one progressive trigger: growth.
In the context of scoliosis, progression means the scoliotic curve will increase in size, and a condition can progress from mild to moderate and severe to very severe.
While each case is unique, with the different classification points shaping variables such as progressive rate, there is no definitive means by which we can predict, with 100-percent accuracy, how fast one patient will progress, compared to another.
As adolescents are in or entering into the stage of puberty, marked by rapid and unpredictable growth spurts, patients diagnosed with this type of scoliosis are at risk for what’s known as rapid-phase progression, which is a feature that makes this type unique.
The most common symptoms of AIS are postural changes that affect the body’s overall symmetry, and again, while each case is different, how noticeable these changes are will depend largely on condition severity; the telltale signs of scoliosis in adolescents often include uneven shoulders and hips.
Another feature that makes this type unique is how challenging it can be to detect early on, and while there are no treatment guarantees, early detection can increase chances of treatment success.
The challenge of early detection is due to the subtlety of postural changes in mild forms, which is why the majority of my patients have already progressed from mild to moderate, when they receive a diagnosis based on more overt symptoms.
In addition, scoliosis isn’t overly known to cause functional deficits until the more severe stages have been reached, and AIS is unique in that this condition type isn’t commonly known to be painful, and this is also related to growth and skeletal maturity.
In patients who are still growing, their spines are undergoing a continuous lengthening motion until they reach skeletal maturity, and this counteracts the compressive force of a scoliotic curve.
The uneven forces introduced by scoliosis can cause compression of the spine and its surrounding ligaments, muscles, and nerves, and this is known to be the main cause of condition-related pain.
Once a condition becomes compressive in adulthood, pain is experienced differently, making adult scoliosis unique in that regard.
Now let’s talk about the most common types of scoliosis in adults: idiopathic and degenerative.
Idiopathic scoliosis in adults is the most prevalent type of adult scoliosis and is an extension of AIS that was left undiagnosed and untreated.
Idiopathic scoliosis in adults is unique because while they might receive their initial scoliosis diagnosis in adulthood, this doesn’t mean they haven’t been living with the condition for years.
The unfortunate reality is that had these patients received a diagnosis and treatment in adolescence, prior to the condition progressing into adulthood and becoming a progressive condition, their spines would be in better shape than by the time I see them.
As mentioned, the signs of scoliosis in adolescents are not always easily noticeable to those untrained in precisely what to look for, and this is particularly the case in mild scoliosis, which is why this type of scoliosis so commonly progresses into adulthood.
Once the spine has settled due to gravity and maturity, the resulting compression causes pain in adults: the number-one reason adult patients come in to see me for a diagnosis and treatment.
Condition-related pain in adults can include back, and radicular pain felt throughout the body, most commonly in the hands, legs, and feet.
For adults diagnosed with idiopathic scoliosis, pain can range from mild and intermittent to chronic and debilitating, and this is largely due to severity and the degree of nerve involvement.
So while this type of scoliosis is not at risk for rapid-phase progression, as in AIS, with increasing age comes a certain degree of expected spinal degeneration, and this leads us nicely into our discussion of scoliosis types with known causation, the first of which is the next most common type of scoliosis found in adults: degenerative scoliosis.
Now that we have explored what makes idiopathic scoliosis unique in both adolescents and adults, let’s move on to address the forms of scoliosis with known causation: degenerative, neuromuscular, congenital, and traumatic scoliosis.
These types of scoliosis are associated with clear causative sources that make them unique, and their underlying causes drive the treatment approach moving forward.
Degenerative scoliosis is also known as de novo scoliosis, because, in contrast to idiopathic scoliosis in adults, degenerative scoliosis develops fresh in adulthood, with no prior history of the condition earlier in life.
In this type, we understand its causation: a combination of natural age-related spinal degeneration and the cumulative effect of certain lifestyle choices.
Degenerative scoliosis is most commonly diagnosed over the age of 40 when people tend to start experiencing age-related spinal degeneration.
While there is a certain degree of natural spinal deterioration expected with age, lifestyle choices can either decrease, or increase, these effects.
Factors such as obesity, low activity levels, chronic poor posture, and repeatedly lifting heavy objects incorrectly can also cause degenerative changes to the spine.
Most often, it’s the spine’s intervertebral discs that are the first spinal structures to face deterioration, and this is why degenerative disc disease is a common feature of degenerative scoliosis.
The spine’s intervertebral discs sit between adjacent vertebrae (bones of the spine) and play many important roles in the spine’s overall health and function: facilitating flexibility, giving the spine structure, and acting as the spine’s shock absorbers.
As such, the discs are key to the spine’s ability to maintain its natural curvatures and alignment.
Once the discs start to deteriorate, they can change shape, and this can affect the position of adjacent vertebrae, causing them to shift out of alignment with the rest of the spine, leading to the development of a scoliotic curve.
As mentioned, idiopathic scoliosis accounts for 80-percent of scoliosis cases, and In addition to degenerative scoliosis, neuromuscular, congenital, and traumatic scoliosis make up the remaining 20 percent with known causation.
Neuromuscular scoliosis develops as a secondary complication of an underlying neuromuscular condition such as cerebral palsy, muscular dystrophy, or spina bifida.
Neuromuscular scoliosis (NMS) is considered an atypical form. It can involve a scoliotic curve bending to the left, towards the heart, and this is a red flag that an underlying pathology accounts for scoliosis development.
In cases of NMS, the nerve and/or muscular disorder at the root of its development has to be the driving force of the treatment, which complicates the process, making it difficult to offer my NMS patients the same type of prognosis I can with more-typical forms.
What makes NMS unique is that it’s caused by a larger medical condition/disease that involves a disconnect in brain-body communication: affecting the brain, spinal cord, and/or muscular system.
While not every neuromuscular condition is going to result in the development of scoliosis, it is a common complication.
Infants are born with congenital scoliosis as it develops in utero, due to issues of bone malformation within the spine itself.
Congenital scoliosis is a rare type, affecting approximately 1 in 10,000, and can be caused by a single vertebra not forming properly (hemivertebra), or vertebrae failing to form into separate and distinct bones, instead fusing together into a solid bone (bony bar).
In severe forms of congenital scoliosis, the spine can form with a combination of the two: a hemivertebra on one side, and a bony bar on the other.
In cases of traumatic scoliosis, the condition develops due to an injury/trauma sustained by the spine.
Common traumas can include fractures caused by falls or car accidents; in addition, the presence of tumors pressing on the spine can also expose it to uneven pressure and force the spine out of alignment, causing the development of a scoliotic curve.
Now that we have explored some of the main types of scoliosis, based on causation, there are also different types of scoliosis based on the specific details of curvature patterns/types.
Scoliosis is often described as a complex and mysterious condition, not just because of the different types based on causation and severity, but also because of the many different curvature patterns/types that further classify a condition.
When viewed from the side, a healthy spine will have a soft ‘S’ shape, and it will appear straight when viewed from the front and/or back, it will appear straight.
The spine’s healthy and natural curvatures make it stronger, more flexible, and better able to absorb and distribute mechanical stress incurred during movement.
There are three main sections of the spine: cervical (neck), thoracic (middle/upper back), and lumbar (lower back), and curvature location is one of the key classification points.
While scoliosis can develop in any of the spine’s sections, it most commonly affects the thoracic and lumbar sections.
Thoracic scoliosis occurs when the scoliotic curve develops in the middle/upper section of the thoracic spine and is the most common curvature location.
This is understandable as the thoracic spine is the longest spinal section consisting of the T1 - T12 vertebral bodies.
A feature of thoracic scoliosis is the development of a rib arch as the unnatural spinal curve can pull on the rib cage, distorting its position and protruding more on one side than the other.
In addition, this curvature location is commonly associated with uneven shoulders and/or one leg appearing longer than the other.
Lumbar scoliosis involves the development of an unnatural spinal curvature in the lower back.
As lumbar scoliosis introduces uneven forces to the lower body, it’s known to cause uneven hips and leg lengths.
In addition, when lumbar scoliosis is compressive in adults, a common complication can be sciatica, as the sciatic nerve starts in the lower back and extends down the buttocks, back of the leg, and foot.
The sciatic nerve is the largest nerve in the body, and depending on the degree of nerve involvement, compression-related back and/or radicular pain can range from mild to debilitating.
When lumbar scoliosis develops later in life, it can be classified as degenerative as the lumbar spine has to bear the most weight and, as such, is the most vulnerable to spinal degeneration/deterioration.
In thoracolumbar scoliosis, the unnatural spinal curve develops in the lower thoracic spine and upper lumbar spine, and as the scoliotic curve spans two spinal sections, it’s known as combined scoliosis.
Curves that involve both the vertebrae of the thoracic and lumbar spine are associated with congenital and/or neuromuscular scoliosis, and while thoracolumbar scoliosis is diagnosed in men, it’s more common in women.
So now that we have addressed the different types of scoliosis curvature patterns, let’s explore a further classification based on curvature type: dextroscoliosis and levoscoliosis.
Dextroscoliosis is considered a typical scoliosis curvature as it bends to the right, away from the heart.
Curvature type tells me whether a scoliosis is considered typical or atypical, which is largely determined by causation, as discussed earlier.
Depending largely on the condition’s severity, dextroscoliosis can either cause the spine to have more of an exaggerated ‘S’ shape or a ‘C’ shape.
Dextroscoliosis can be diagnosed at any age or gender but, it is most commonly found in adolescent females.
Levoscoliosis is considered an atypical scoliosis curvature because it bends to the left, towards the heart.
When I see this curvature type in an X-ray, this is a red flag for me that there is an underlying pathology at the root of the scoliosis development.
Levoscoliosis is commonly associated with congenital, neuromuscular, and/or traumatic scoliosis.
Despite scoliosis being around since ancient times, there is still a lot to learn about the condition, particularly in terms of causation.
While me might not understand what causes the condition’s most-prevalent type (idiopathic scoliosis), we most certainly know how to treat it moving forward. I also remind patients that even if we did understand its cause, it wouldn’t necessarily change the course of treatment or its outcome; what’s more important is how to respond to the condition’s presence once diagnosed.
As a progressive condition, where scoliosis is at the time of diagnosis is not indicative of where it will stay, which is why proactive treatment is so important. One of my main goals of treatment is to prevent increasing condition severity, related symptoms, and the need for more invasive forms of treatment in the future.
As the spine is such a complex structure with so many moving parts, it’s not surprising that a structural spinal condition like scoliosis can have so many variations, which is also why further classifying the condition is so important.
Complex conditions like scoliosis are classified as specifically as possible, not only because this streamlines the treatment process, but also because these classification points shape a person's experience of life with the condition and guide the treatment approach.
From causation to severity, curvature location, and direction, there are multiple different types of scoliosis, making each case unique, and necessitating the design of highly-customized treatment plans.
Here at the Scoliosis Reduction Center, I have experience treating all types and severity levels of scoliosis from typical idiopathic cases, to atypical neuromuscular, congenital, and traumatic scoliosis patients.
Regardless of type, the time to act, in terms of treatment, is always now; if you or someone you care about has been recently diagnosed, don’t hesitate to reach out to us here for additional guidance and support.