Adolescent (Idiopathic) Scoliosis

But first...

The word idiopathic means - more or less - that the cause of the scoliosis is unknown. Nitpicking, this holds, if you seek cause to be more and more specific. We know a good amount about what is going on, actually.

Idiopathic does not imply that everything that has an unknown cause gets lumped in here. This group has a rather tight consistency within it. In fact deviation from the usual pattern requires rethinking and looking for other stuff. So, the generalities are more important than just allowing a category to exist.

Typically this is a condition that becomes prominent going into and during puberty. Straight growth becomes asymmetric, and in a rather stereotypic way. Similar patterns of scoliosis can occur in toddlers, or in juveniles. However, the way those children react to treatment is different enough to give them their own groupings. This is essential to the way we group things. Given a diagnosis the first question is always, What will happen next?

Also, there are cosmetic considerations and there are medical considerations. Most data with public health orientation is directed at the latter. Keep in mind that certain data derives the framework of measurement by things such as breathing, ability to walk, and eat. A given look in a bikini is not reflected in such medical data.

Another easy point to give confusion is that if incidence. Humans are not robots. None of us claims perfect right to left symmetry. The degree of deviation is important and the prospects that the curve can or will worsen.

WHAT IS ADOLESCENT IDIOPATHIC SCOLIOSIS?

The spine is made up of a series bones called “vertebrae.” These vertebrae are connected to each other by discs and connective tissue. These vertebrae make up different sections of the spine from top to bottom. These sections include the cervical (vertebra in the neck), thoracic (vertebra in the chest), lumbar (vertebra of the low back) and sacral (located just above the tail bone). Each vertebra is numbered starting at the top in each section. Adolescent idiopathic scoliosis can present as curvature of the thoracic and lumbar spine. 

DEFINITION

The definition of idiopathic scoliosis is a lateral curvature of the spine with rotation of unknown etiology  It is important to recognize that scoliosis should only be considered idiopathic after other causes of scoliosis have been excluded.

CLASSIFICATION OF IDIOPATHIC SCOLIOSIS:

Basically there are three categories of idiopathic scoliosis. The first is infantile scoliosis. This is defined as the onset between birth and the age of three. The next is juvenile scoliosis which has its onset between the ages of 4-10. The last is adolescent scoliosis which develops after age 10.

EPIDEMIOLOGY:

By definition “idiopathic” scoliosis has no known etiology. We do, however, know that the prevalence of the disease in patients with a Cobb angle of greater than 10 degrees is in the range of 1.9% - 3%. The prevalence of patients with a Cobb angle of greater than 20 degrees is .3%. Within this group of patients, however, there is definitely a female predominance. 

THEORETICAL ETIOLOGY:

Although we have already stated that there is no known etiology in idiopathic scoliosis, many causes have been theorized. The genetic relationship in scoliosis has been a hotly debated topic, but it is poorly understood. Approximately 30% of patients who have scoliosis have a positive family history for the disease. However, presence of a family history is predictive in determining the risk of progression or in correlating with the magnitude of the curves. In other words, just because a patient has a family member with a large scoliotic curve this does not put the patient at a greater risk than the general population of having a large curve.

Other etiologies that have been entertained, have been some alteration in basic connective tissue or some neurologic disturbance of the equilibrium system. Unfortunately all of these theories have proven inconclusive.

HISTORY OF THE DISEASE IN UNTREATED ADULTS:

 One must ask the basic question as to why do we treat children with scoliosis. This further begs the obvious question as to what would happen to patients in adulthood if we left them untreated. There are four main problems found in adults with scoliosis. They include backache, diminished pulmonary function, psychosocial problems and increased mortality. Backache is common to patients without scoliosis. Approximately 80% of the population of North America at one time in their life will report to a physician of a problem related to low back pain. The incidence of backache in patients with scoliosis in general is similar to the general public. Approximately 40-60% of scoliosis patients will complain of intermittent backache. Certainly, however, patients who have thoracolumbar or lumbar curves with pronounced degenerative

changes and transitory shifts have a greater incidence of pain in the lumbar region and also accompanying radicular complaints. When one sees patients in their 50s and 60s with lumbar scoliotic curves, oftentimes they had straight spines in adolescence. When scoliosis develops in this older population with a previous history of a straight spine, this is classified as degenerative scoliosis as differentiated from progressive idiopathic scoliosis.

 While we worry more about pain syndromes in lumbar curves, it is the thoracic curves that will truly affect pulmonary function. It is a misconception, however, that mild to moderate curves in the thoracic spine severely diminish lung function. The FVC and FEV subscript 1 are decreased in curves as they approach 100 to 120 degrees. The particular pattern of dysfunction in nonsmokers with severe scoliosis is uniformly that of restrictive lung disease. With increasing lung disease, in severe cases, cardiac function can be affected.

Psychosocial programs have been identified in patients with scoliosis. There is no clear cut relationship between the location of the degree of curve and the magnitude of psychosocial effects however. As with other disorders, any type of cosmetic deformity will affect patients in different ways depending on their underlying psychological make up.

MORTALITY RATES:

 The mortality rates in adolescent idiopathic scoliosis is comparable to that of the general public. Once again, the risk of morbidity and mortality in this disease process is limited to thoracic curves that exceed 100 degrees. The mortality is secondary to pulmonary hypertension and right heart failure.

 EXAMINATION:

Taking a careful history with the scoliosis patient is very important. Obviously we wish to document family history of the disease, although its exact relevance to the patient’s prognosis or disease process does remain unclear. Since most scoliosis is nonpainful, it is quite important to determine whether the patient has any pain or interference with activities. Any neurologic signs or symptoms will be important to help in the determination that indeed this is an idiopathic scoliosis rather than secondary to some neurogenic cause. An important factor in females will be to note the onset of menarche and in both males and females a history of recent growth spurts.

CURVE MEASUREMENT:

The Cobb angle is the critical measurement in idiopathic scoliosis. It is important to measure all curves. When one considers the Cobb angle on a single curve, we basically define the upper end vertebra as the upper vertebra which is tilted maximally into the curve and the lower end vertebra as the lower vertebra which is tilted maximally below the curve. When measuring double curves, there will be a transitional vertebra between the upper end vertebra of the upper curve and the lower end vertebra of the lower curve. The inferior endplate of this transitional vertebra represents the inferior aspect of the upper curve and the superior endplate of the transitional vertebra represents the upper end of the lower curve.

 When measuring the Cobb angle, a parallel line is drawn along the superior endplate of the upper end vertebra and along the inferior endplate of the lower end vertebra. Right angles are dropped from these lines and the intervening angle is the measurement of the scoliotic curve or the Cobb angle.  The apical vertebra is either the vertebra or in some cases disc space that represents the center of each curve.

RISSER SIGN

(Something you see on the x-ray. The cap of the pelvis is cartilage and does not show up on x-rays until it begins to calcify as its growth - and that of the spine - are beginning to slow to eventually stop. Like an eyebrow getting bigger, it grows longer from the outer pelvic edge toward the midline.)

The Risser sign is an important factor in determining skeletal maturity in the growing child and is easy to assess from the spine radiographs which include the top of the iliac wings. The iliac apophysis generally matures by starting to ossify at the anterolateral portion of the iliac crest and then progressively moves posteromedially. When maturation of the crest is complete, the fully formed crest fuses with the remaining ilium. The Risser sign refers to the amount of maturation and is frequently used to determine risk progression. The absence of any ossification of the iliac wing is referred to as Risser 0. When ossification has proceeded up to less than 25% of across the iliac crest, it is a Risser1, up to 50%, a Risser 2, up to 75% a Risser 3 and up to 100% a Risser 4. When the crest fuses with the ilium, this is referred to as Risser 5 and a sign of skeletal maturity.

PREDICTING CURVE PROGRESSION:

 Once a curve has presented, the physician and family alike look to seek prognostic indicators that will predict curve progression. While many prognostic indicators have been discussed, there is evidence to suggest that thoracic curves that present earlier on are more likely to progress than lumbar curves. Furthermore, double curves progress more frequently than single curves. Intuitively, it has been thought that family history, the amount of rotation or perhaps the gender of the patient might be helpful in predicting progression. Unfortunately, none of these factors have been proven to be accurate in predicting curve progression. Statistically, however, curves that are less than 19 degrees in a patient who is Risser 0 or 1 have approximately a 22% chance of progression. If the patient is a Risser 2-4, there is only a 1.6% chance of progression. Curves of higher magnitude in the 20-29 degree range and a Risser 0-1 category have a 68% chance of progression while this drops off in the Risser 2-4 category to 22%. 

The magnitude of the curve at presentation is critical entry point of the patient into an algorithm of care. Immature patients who present with a curve of less than 25 degrees are just observed. When one gets into that 25-29 degree range, this is a gray area for treatment. If the patient is quite young and has a great deal of growth remaining, it would be reasonable to consider that patient as a candidate for some type of brace treatment. If the patient is more skeletally mature and has already passed through a significant growth spurt and is reaching near the anticipated adult height, it would be more reasonable to watch that patient. Certainly it has been proven that for patients in the Risser 0-2 range, a curve that presents in the 30-40 degree range should be immediately braced in an effort to prevent the curve from progressing. If the immature patient presents in the 45-55 degree range, it is no longer reasonable to consider bracing as a significant alternative. 

SCREENING FOR SCOLIOSIS:

 We know that if curves are caught early enough, bracing may be an effective treatment to ward off curve progression and possible surgical intervention. Mandating screening in the schools became a popular social issue.  Unfortunately the screening of school children, usually by a relatively inexperienced person, for curvatures of the spine was not as much of a panacea as had been originally intended. When looking at the patients of a screened population between the age of 10 and 16, of the total population only .6% actually required any form of treatment. When isolated females, this was approximately 1% and in males, .1%. One can see that the yield of patients is relatively low in this process. Because so many children are flagged for an evaluation and do not require treatment, some pundits have referred to these patients as having “schooliosis”. This has brought about a re-evaluation of the need for school screening at all.

NON-OPERATIVE TREATMENTS:

Manipulation and Exercise

There have been a host of nonoperative treatments over the years for scoliosis including various forms of exercises, spinal manipulation, brace treatments and including electrical stimulation. While exercises have not been shown to affect the natural history of scoliosis and have no role in controlling progressive curves, they should be encouraged to maintain overall fitness in the scoliotic patient. While manipulative treatments have been suggested by some, there is no evidence to document that any form of spinal manipulation nor traction therapy has any long term therapeutic effect in controlling curves. 

 Lateral Electrical Spinal Stimulation (L.E.S.S.)

Electrical stimulation of muscle groups has found general acceptance in physical therapy. A technique for electrical stimulation of the spine in scoliosis was known as L.E.S.S.  L.E.S.S. stands for lateral electrical spinal stimulation. Electrical stimulation either through an implanted electrode or through skin leads may show some apparent correction of the curve during the stimulation, however there has been no evidence to suggest that the long term results are any better than the natural history of the disease process.

 Treatment

 For many years, brace treatment had been recommended for scoliosis, although it was difficult to evaluate the results. A cooperative study through the Scoliosis Research Society finally was able to document in a scientific way that bracing for scoliosis is effective given specific criteria. The indications for brace treatment are the skeletally immature patient of Risser 0, 1 or 2. The curve must be in the range of approximately 20-40 degrees and the patient must be willing to accept brace treatment. Lastly, at the initiation of treatment, the patient must have a deformity that they would consider cosmetically acceptable at the end of treatment. While at the conclusion of brace treatment, a patient’s curve may be diminished from that of the initial presentation, evidence reveals that in ensuing years the curve will progress back to where the patient originally presented. Therefore it is critically important to let the patient and the patient’s family understand this. If they consider the deformity at the time of initial presentation as cosmetically unacceptable, there is no reason to undertake the physically and psychologically demanding effects of brace treatment on a growing child. The contraindications to brace treatment would be the skeletally mature patient, a curve less than 25 degrees without any documented progression, curves over 45 degrees, a significant amount of thoracic lordosis which would make brace treatment ineffective, an unsupportive home life or the noncompliant patient.

Milwaukee Brace

One of the most widely used initial braces for scoliosis was the Milwaukee brace which is technically classified as a cervical thoracic lumbar sacral orthosis. This was originated by Blount and Schmidt in 1946. The brace, which is a combination of pads and metal retainers controls lumbar lordosis by instilling a forward pelvic tilt. The lateral lumbar curves are controlled by direct pressure from pads. There is a throat mold which maintains the head position over occipital pads and molded thoracic pads. The brace is effective for curves with apices into the upper thoracic spine. While quite effective at maintaining pressure on various points of the spine, it is a difficult device for the patient to wear both from a comfort as well as a cosmetic viewpoint.

 Underarm Thoracolumbar Sacral Orthoses (TLSO)

In an attempt to improve patient compliance the underarm brace or TLSO was developed. This brace has been called the New York Orthopedic Brace or modified in a version to be called the Boston Brace. They are both plastic molded underarm thoracolumbar sacral orthoses. Mechanically, the brace is a completely passive device. Carefully positioned pads inside the brace push on the prominences to effect partial curve correction. These braces do have improved patient compliance because of comfort and because of improved cosmesis. Technically the braces are only indicated for curves with an apex below T7 or T8. This upper limit has been modified to a certain degree by the inclusion of clavicular bars and over the shoulder straps in an attempt to avoid using the more cumbersome Milwaukee brace.

Orthotic Protocols

 The protocol for orthotic use generally includes brace for approximately 23 hours per day. The patient should be visited every three months for brace adjustments, not only due to patient growth but also due to breakdown of brace components. New radiographs are indicated at approximately six month intervals. As the patient approaches skeletal maturity, the brace is gradually weaned over a 2-3 year period, although the exact rate of weaning varies from clinician to clinician. Often the weaning process ends with the brace being worn only at night up until full skeletal maturity. Patients are generally checked thereafter at approximately two year intervals.

 RESULTS OF ORTHOTIC TREATMENT:

 Once the brace is fitted to patient and X-ray is obtained upright in the brace. Depending on the flexibility of the curve there is usually there is an initial improvement in the curve measurements. Over time, there may be a gradual loss of correction. With successful brace treatment the average curve, post-bracing, is 10-15 degrees better than the pre-brace curve. At longer follow up, 5 or more years out of the brace, the average curve progresses to the pre-brace curve.  For this reason before initiating brace treatment patient and family must be comfortable with the cosmetic appearance of the patient. Once initiated the overall failure rate for bracing is approximately 40%.

Operative Treatments: Overview

 Posterior Instrumentation

Historically the most common procedures were posterior operations. The original operations were mostly Harrington rod procedures. Harrington rods connected to the spine only at the top and the bottom of the rod. Therefore the amount of fixation to the spine was limited. Over the course of time surgeons moved on to techniques that allowed for increased fixation over multiple segments of the spine. This became known as “Segmental Fixation”. The initial example of this was developed by Eduardo Luque of Mexico City. In the warm climate of his country post-operative casts or braces were impossible to use. He therefore supplimented his procedures by adding sub-laminar wires to connect to a pair of smooth rods. This was known as Luque Instrumentation. The use of the sub-laminar wires was carried over to Harrington Rods and the procedure often referred to as a Harri-Luque Instrumentation. Since Paul Harrington was from Texas and Luque was from Mexico the procedure was often called a “Tex-Mex”.

 Influenced by Luque , Cotrel in France developed his on method of inserting two rods into the spine and gaining segmental fixation via a variety of hooks. Jean Dubousset worked with him to develop a technique of curve correction via rod rotation. The Cotrel-Dubousset or CD instrumentation became the standard of care for posterior surgery. Now there are a variety of different systems available that mimic or improve upon the original CD instrumentaion.

Anterior Instrumentation

Here we see the Harrington Rod ( a rod with hooks at each end, one of which can be jacked outward). This rod is placed on the spine from behind - posterior).

One of the first frontal stabilization techniques as a tension cable spanning a series of screws fixed into the vertebral bodies from the front. Whereas the rod stretched to get the spine straighter - a very limited ability, the cable devised by Dwyer, followed the total removal of disc material between vertebra. Removal of substance allowed huge reduction of deformity without stretch and also produced amazing correction of horizontal rotational deformity.

In this case, the Dwyer was done first to attain more correction than a Harrington Rod could wish for. Then the posterior rod was added to balance the correction and make the construct stiffer and stronger.

This was the gold standard - for a while.

Over the course of time anterior surgery has become more popular for a number of reasons. It has been most commonly utilized for single lumbar or thoracolumbar curves. One of the benefits is the preservation of motion segments below the fused curve. There is also the benefit of increased curve correction and possibly some derotation of the curve.

The original system , the Dwyer Instrumentation , was a screw and cable system.. This was mostly used in severe neuromuscular curves. In idiopathic scoliosis the next system was the Zielke Rod System. This was a powerful corrective tool but resulted in a localized loss of lordosis. Since these were mostly used in the Thoraco-lumbar and lumbar spine this loss of lordosis was a major draw-back. The modern descendent of this system is the Miami-Moss Instrumentation system with similar drawbacks of loss of lordosis unless specific “lordosis-sparing” techniques are utilized.

Combined Operative Approaches

Combined Anterior and Posterior approaches to the spine are used for large stiff curves or in double major curves where the surgeon is looking to stop the lowest most fused segment shorter and save a motion segment in the lumbar spine.

Another usefulness of combined procedures is to prevent the “Crankshaft Phenomenon”.  This difficult post-operative complication results in performing a posterior only operation in a skeletally immature child. While intial excellent curve correction may be obtained the curve continues to progress via continued anterior growth. This occurs in the face of and intact fusion mass and intact instrumentation.  

Just consider the horrible deformity on the left. The anterior attack on the worst part of the curve makes monumental correction possible. It needs a broader hold than the anterior devices can span, however and thus the two prong attack on the very advanced cases.

Example of Crank-Shaft Phenomenom:

The fellow on the right was referred because a “successful” posterior fusion with dual rod stabilization had over time become unsightly. The back contour was, by all accounts, made near normal by the surgery. Two issues: Boys mature late, so growth potential is greater than the girls at this young teen age, and rods do not have the ability to not rotate on the vertical axis unless firmly fixed deep into bone at many levels along the spine (as with vertebral screws). To prevent crankshaft, the apex of the curve had to be fused anteriorly lest this occur.

OPERATIVE TREATMENTS:

Obviously for curves that present in excess of 45 degrees or for patients who have failed brace treatment, operative treatment is the remaining choice. The indications for operative treatment generally include curves greater than 40 degrees at presentation in the growing child. Progression of curvature noted at the onset of a growth spurt in a skeletally immature patient while undergoing brace treatment is another indication for considering surgery. In a mature adolescent, curves that either progress to or are noted to be in the 50-60 degree range are a further indication. Once surgery is indicated, the surgeon must consider the approach to the spine he wishes to employ. While posterior spine surgery for scoliosis is the classic, there has been increased understanding and usage of anterior corrective measures. In some cases, both an anterior and a posterior surgery would be necessary to obtain an optimal postoperative result. Methods of fusion which attain curve correction, prevention of progression, and fuse as few segments as possible are the desired objective.

The King Moe classification has been widely utilized in understanding and planning for operative correction. 

King-Moe Type I

The King Moe type I curve is a double curve of the thoracic and lumbar spine. The patient will demonstrate both thoracic and lumbar prominences on physical examination. Both curves cross the midline. The lumbar curve may be larger and more rigid than the thoracic curve. These curves represent true double major curves. Both curves are structural. By this I mean that on side bending films, both curves will have a significant residual curvature when bending into the curve. Curves that correct significantly on side-bending into the curve are “flexible” and considered nonstructural. The classic treatment for King Moe type I curves has been an instrumented posterior spine fusion of both the thoracic and the lumbar curves. Recently, in order to preserve mobility of the spine, interest has focused on a selective anterior instrumented spine fusion of the lumbar curve only with the thought that the thoracic curve will decrease over time. 

King-Moe Type II

 The King Moe type II curve is once again double curves of both the thoracic and the lumbar spine. There is, however, on physical examination, a minimal lumbar prominence. Both curves once again cross the midline. In this particular circumstance, however, the lumbar curve is much more flexible. This represents a false double major pattern. In other words, the thoracic curve is the primary structural curve and the lumbar curve is a compensatory curve which remains flexible. In these types of King Moe type II curves, it is important to fuse the primary thoracic curve and not to fuse the lumbar curve since the bending films indicate it will probably correct spontaneously with thoracic curve correction. Classically these were fused posteriorly, first with various forms of Harrington instrumentation. This progressed to the various forms of segmental spine fixation which presently includes some type of dual rod technique with hooks and cross links. Additional experience with anterior surgery has furthered the use of anterior instrumentation and fusion into these primary thoracic curves where it is important to fuse the entire Cobb angle from the top end vertebra to the lower end vertebra.

King-Moe Type III

 The King Moe type III curve is a thoracic curve with minimal or no decompensation. In other words this is a single primary thoracic curve. The lumbar curve, while present is less in magnitude and does not cross the midline. These King Moe type III curves lend themselves to shorter, pure thoracic fusions either through the posterior approach or through an anterior approach.

King-Moe Type IV

The King Moe type IV curve is a very long thoracic curve with a marked trunk decompensation. It is not until the lower lumbar region, usually at L4 that the curve reaches back to the midline. The L4 vertebral body still tilts into the curve.  These long C-shaped thoracic or thoracolumbar curves really lend themselves best to treatment via a posterior instrumentation. The correct level inferiorly will depend on the bending films to determine which of the lower lumbar vertebra completely bends backward to the neutral position.

King-Moe Type V

 The King Moe type V curve is a particularly interesting curve in that there are two curves, but both within the thoracic region. These double thoracic curves often have extension into the cervical spine and will frequently have a third compensatory lumbar curve. It is important to document, both on physical exam and on x-ray, the status of the cervical thoracic junction. A true King Moe type V curve will have a prominent abnormality of the neckline usually with a prominence of the left trapezial region. On x-ray there will be a tilting of the top endplate of T1. Further on physical exam, one will note a high left thoracic prominence and a low right thoracic prominence. On bending x-rays, the upper left curve will prove to be inflexible and therefore structural. The treatment of the King Moe type V curve must include fusion of the upper thoracic curve. If the left shoulder is elevated pre-operatively, isolated correction of the lower thoracic curve will exaggerate the shoulder imbalance. It is imperatively important to assess these patients accurately pre-operatively or else a significant structural and cosmetic deformity will result post-operatively. If one has the tip off of shoulder asymmetry pre-operatively, it is easier to understand the necessity for fusing both curves. If however, the patient presents pre-operatively with balanced shoulders but has a rigid left thoracic or even cervical thoracic curve, both thoracic curves must be fused. If the shoulders are balanced with a rigid right thoracic curve, but a very flexible left thoracic or cervical thoracic curve, it is then feasible to only fuse the lower curve since there will be compensation within the upper curve.

Summary

 Adolescent scoliosis is a fascinating topic which is in a constant state of evolution and updating of opinions and experiences. Rarely in medicine does a surgeon have the ability to make such a dramatic visible alteration to the structure of the human body as in scoliosis corrective surgery. Understanding the topic can seem a daunting challenge. With a thorough understanding of the definitions and basic principles a gradual enlightenment should hopefully follow.

Curve Magnitude and Treatment

At sixteen years of age, this girl has lost 67% of her lung function. This will shorten her life in addition to making her disabled by way of respiratory insufficiency. Notice that the “hump” is not spine which has spun sharply clockwise. That hump is rib cage. The ribs have folded as well as rotated backward.

In the past, even the best of surgeons would have considered this example inoperable. This as well as the other young girl would also have a short bleak life span. The trips to “third world” are hard work but nobody is complaining.