"Adolescent Idiopathic Scoliosis"


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What is Scoliosis?

what is scoliosis

Scoliosis is an abnormal curvature of the spine.  

There are three types of scoliosis and they are distinguished based on how old the person is when it occurs.  There is infantile scoliosis occurring at 0 - 3 years old, then juvenile scoliosis occurring at 3 - 10 years old, and then the most common type, adolescent scoliosis, occurring 10 yrs old until the end of growth (around 16 years old).  We will focus on adolescent scoliosis because it includes 80% of patients that develop scoliosis (contact us for information about the other types).

Adolescent scoliosis is described as "idiopathic", meaning doctors still do not know why it occurs.

Doctors do know that it occurs more commonly in females...the female to male ratio is 4:1 in mild curves (meaning 4x more common in females) and 7:1 in more severe curves (7x more common in females).  

As we go through puberty, our spine grows just like our arms and legs.  Our spine is made of many vertebral bones stacked on top of each other and held in place by ligaments.  Each of these bones in your spine (the vertebrae) have growth plates where growth occurs, and adolescent scoliosis probably occurs because these growth plates are not growing at a perfectly equal rate, causing the spine to bend.  

We consider a curve "scoliosis" when its over 10° (this angle is called the "Cobb angle" and its measured on x-ray).  Any curve less than 10° is just a variation of normal... if we x-ray'd everyone, about 3 out of 100 people have a curve more than 0° but less than 10°.  

Lets talk more about the curve in scoliosis.  Its irregular in three ways.  (1) the spine curves to the side so if you look at someones back with scoliosis the spine doesn’t run straight up and down; (2) the spine is also rotated, each of the vertebrae within the scoliosis curve are rotated toward the side of the curve, which causes the ribs to be more prominent on the side of the curve; (3) the natural kyphosis curve of the thoracic spine is blunted, making a “flatter” back (the thoracic spine, where your rib cage comes off, normally has a small hump of about 20-40°).

Finally, lets quickly review the basic anatomy of our spine.  The spine has four segments going from your head to your bottom.  The first is the cervical spine, then thoracic, then lumbar, and then sacral.  The curve in scoliosis usually occurs in the thoracic spine, occasionally in the lumbar spine, but rarely involves the entire back.

How is a Scoliosis diagnosed?

Even though the spine deformity can look significant in scoliosis, most kids have few symptoms. 

Back pain is rare! Which is great.  

Kids sometimes complain of occasional back discomfort, but thats pretty non-specific...who doesn’t back discomfort time to time from sleeping in a bad position.  

Usually the biggest complaint is cosmetic - patients don’t like how they look, and so the appearance of a child's back is usually how scoliosis is diagnosed.  

Most middle schools and many pediatricians also screen kids for scoliosis. Scoliosis is screened for by having kids bend forward to touch their toes (called the Adam's Test).  This accentuates a scoliosis curve because the ribs on one side are more prominent from the rotational component of scoliosis.  While the child is leaning forward a measuring guide is placed on their back, and measurements over 7° are referred to an orthopedic doctor (this 7° corresponds to about 20° curve). 

Doctors and nurses also look for signs of shoulder asymmetry (one shoulder rests higher than the other); the appearance of a prominent hip (looks like one hip is sticking out to the side); and the head is not centered over the lower back (called a trunk shift).  

Neurologic issues like numbness or weakness in the arms or legs is also incredibly rare.  If someone complains of numbness/tingling in their legs, doctors typically get an MRI to look for neurologic disorders causing the spine curve, such as tumors, diastematomyelia, spina bifida, or a tethered spinal cord, syringomyleia. 

Although there are reports that an abnormal spinal curve will affect the rib cage and therefore breathing, it takes a severe severe curve (around 100°) to cause breathing symptoms.  So respiratory failure is very uncommon. 

When a kid presents with signs of scoliosis, full-length x-rays of the entire spine are ordered.  The doctor then measures the angle of the abnormal curvature (Cobb anlge), and also looks at the bones to determine how much growth is remaining in the child.  The doctor will use this information to determine the best treatment.  

How is Scoliosis treated?

how is scoliosis treated?  nonoperative bracing of scoliosis. surgical treatment of scoliosis with pedicle screws

Does all scoliosis require treatment?  

The answer is no.  Treatment depends on the severity of the spinal curvature.  Curves that are less than 10° are not even considered scoliosis, they are just a variation of normal, so doctors only diagnose a child with "scoliosis" if the curve is > 10°. Then the curve is categorized as "mild" "moderate" or "severe".   Mild is a curve 10 - 25°.  Moderate is 25-45°. Severe is over 45°.  

The degrees of curvature is just one factor that helps to determine treatment.  Other factors include: the rate of curve progression over the next few months (is it rapidly getting worse?), the skeletal maturity (how much growth remains?), and the overall appearance of the curve.  Lets look at each of these in more detail.

How do you measure the severity of scoliosis. Cobb angle.  What is mild scoliosis, what is moderate scoliosis what is severe scoliosis

Skeletal maturity.  A "mild" and "moderate" scoliosis curve (anything < 40°) only gets worse while a kid is growing.  Once the kid stops growing, the scoliosis usually stops too.  In contrast, a "severe" curve often continues to get worse even after a child has stopped growing.  

In mild and moderate curves, doctors want to know how much growth a child has left to determine the risk that the curve will continue to progress.  Doctors determine growth potential by 1) looking at the parents to see how tall they are; 2) looking at the bones on x-ray (described as "Risser" grades); 3) asking about how far into puberty a patient is (for example, girls tend to grow for 18-24 months after their first period, this first period correlates with a bone age of Risser 1).  Girls typically stop growing around 14 years old, while Boys stop growing around 16 years old (however, this is just a generalization, and boys in particular can continue to grow up to 18-21 years old and they must be monitored for a longer time).  

To emphasize the importance of remaining growth, we can look at someone with a "moderate" curve of 20°.  If they have a lot of growth left (risser 0 or 1), they have a 68% chance of curve progressing to a point where it’s at risk for notable deformity.  That same curve in someone that’s past their peak growth spurt, and starting to slow down (risser 2 or 3), has only a 5% chance of curve progression.  You can see how important growth potential is when studying scoliosis.

Kids with a "mild" scoliosis curve will be monitored every few months with an x-ray to look for signs of progression.  Mild curves are treated the same way in kids with a lot of growth potential and in kids near the end of puberty.  Close monitoring is the name of the game.  If the curve increases by more than 5°, doctors consider it to be progressing so its often watched more closely.  

Kids with a "moderate" scoliosis are treated based on growth potential. In immature kids (ie pre-menarche), a curve over 25° will get a brace right away.  A brace is molded specifically to the location of a child's scoliosis curve to straighten it out.  The brace rarely reverses the curve that has already formed, its job is to prevent the curve from getting worse.  For the brace to work, it must be worn 16-20 hours a day (the exact number is determined by your doctor), and if a kid cheats by only wearing the brace for a few hours a day, the brace does not work.   Braces have come a long way from the initial Milwaukee brace developed before 1950, which was very bulky, had these big side straps, and connected the neck to the back to the pelvis.  Not very comfortable, and a nightmare for many high school students that just want to fit in!  The current brace, Boston, is now the most common and a big improvement, and doesnt go up to the neck (it stays under the armpits).  

In kids further along in puberty (less growth potential) a brace can be started only when the curve is more severe, maybe around 30°- 40°, or if doctors see signs of rapid progression (increase > 5° in only a few months).  When kids midway through puberty come in with a curve 20-30° doctors get xrays every 4 months until growth slows down, but will not brace.

So far we have talked about the role of brace treatment, but surgery is also a form of treatment.  Surgery is performed to fuse the curved vertebre using pedicle screws and bone graft.  Unlike the brace which only stops a curve from getting worse, surgery actually corrects the curve, reducing its size an average of 60%.

Surgery is often recommended in severe cases (a curve >45°).  When the curve is >45°, it can continue to worsen with age, even after the child has stopped growing...while curves < 45° typically stop getting worse once the kid stops growing.  

The other role of surgery is to improve cosmetic appearance.  Remember that surgery actually straightens out the spine, almost completely in many cases.  Some kids that are very skinny show signs of a scoliosis deformity and have psychologic problems as a result.  While no doctor should perform surgery to straighten out mild curves (they are hardly noticable), some surgeons will correct curves of 35 - 40° in skinny female teenagers because it has the potential to improve their confidence and psychological state.  This is an area of controversy.  

It is important to recognize that all treatments for adolescent idiopathic scoliosis are designed to prevent curve progression because a progressive curvature causes a more obvious physical deformity.  Essentially doctors are treating cosmetics (someones appearance).  There is no good research to suggest that scoliosis is linked to back pain.  Therefore, surgery is improving appearance, but it is not reducing risk for back pain or future medical issues.  

What is the long term outcome?  

Treatment of scoliosis is all about controlling the abnormal curve..making sure that it stops growing so there are no issues as an adult.  

Although back pain is a concern with scoliosis, long-term studies that follow people with various degrees of scoliosis severity, have shown that back pain is not a major problem in people with scoliosis, and is not improved by surgery.  This may come as a surprise but studies show that back pain is only slightly higher than the normal population.  And when you factor in back pain that results from surgical treatments (it is a complication of surgery) then it becomes more apparent that surgery should not be done to prevent future back pain.  Respiratory problems from a bent spine is also not a life threatening issue unless the curvature is severe (which is seen in child with syndromes such as muscular dystrophy).   Therefore, the major reason to treat scoliosis is to improve cosmetic results.  And studies have shown that people that have their spine deformity corrected (with bracing or surgery) are happier and feel better about themselves.  





1. Weinstein SL, Zavala DC, Ponseti IV. Idiopathic scoliosis: long-term follow-up and prognosis in untreated patients. JBJS Am 1981; 63(5): 702-12. see article. no significant association with back pain. curves over 50 degrees progressed.

2. Weinstein SL, Ponseti IV. Curve progression in idiopathic scoliosis. J Bone Joint Surg Am 1983;65(4):447–455. see article.  40 year fu.  

3. Weinstein SL et al. Health and function of patients with untreated idiopathic scoliosis: a 50-year natural history study. JAMA 2003; 289(5): 559-67. see article. mild increase in mild back pain, cosmetic concerns. no other effects long term with no treatment.

4. Lonstein JE, Carlson JM. The prediction of curve progression in untreated idiopathic scoliosis during growth. JBJS Am. 1984; 66(7): 1061-71. see article.  risk of progression depends on curve size and risser score.  

5. Kostuik JP, Bentivoglio J. The incidence of low-back pain in adult scoliosis. Spine 1981;6(3):268–273. see article. worse curves are correlated with worsen pain.

6. Danielsson AJ et al. Health-related quality of life in patients with adolescent idiopathic scoliosis: A matched follow-up at least 20 years after treatment with brace or surgery. Eur Spine J 2001;10(4):278–288. see article. majority of untreated AIS are married with normal jobs. no major effect on physical function. 


8. Early Detection of Idiopathic Scoliosis in Adolescents M. Timothy Hresko, MD; Vishwas Talwalkar, MD; Richard Schwend, MD J Bone Joint Surg Am, 2016 Aug 17; 98 (16)