Scoliosis

Author: Dr Vedat Deviren University of California San Francisco 2008-07-09

Scoliosis: Pediatric Scoliosis/Adult Scoliosis

Scoliosis is defined as a lateral curvature of the spine in the frontal plane of the body, which means that the vertebral column bends from side-to-side. Normally, the spine is straight. With scoliosis, the spine curves to the side in the shape of the letter “S” or “C”.  This can cause small but noticeable changes in the alignment of the entire trunk of the body, and the ribs or hips may stick out more on one side than the other side. Additionally, one shoulder may be lower than the other. Furthermore, a severely scoliotic spine may create asymmetries in the shoulder, thoracic cage and pelvis leading to trunk imbalance and significant cosmetic deformity. Scoliosis curves of greater than 10° affect 0.5-3% of the adolescent population and studies reported scoliosis observed up to 32% of adult population after the age of 60.

Scoliosis, by definition, is the lateral curvature of the vertebral column of ten degrees or more. Many people have some curve in their spine. In fact, small spinal curves, less than 10 degrees, are considered a normal variation of the spine. Scoliosis often results in a twisted vertebral column. Scoliosis is a 3-D deformity and the scoliotic spine also demonstrates lateral and axial plane alterations. Therefore, all three body planes must be considered in the evaluation and treatment of scoliosis.

Etiologies (causes of origin) of Scoliosis

The causes of scoliosis are plentiful. There are several categories into which scoliosis as a general syndrome is separated. The most common form of scoliosis (over 85% of cases) is called "idiopathic scoliosis.” This simply means that the cause is not known. An additional way to classify scoliosis is to categorize the curve as structural or nonstructural curvatures.

Structural In this type of scoliosis, the structure of the spine is not normal. Either the lateral bending of spine is asymmetric or the involved vertebra's are fixed in a rotated position or both.  This type of curve is a type that the patient either cannot correct or can correct but is unable to keep corrected. The curvature could be idiopathic, or caused by other disease processes such as birth defects, muscular dystrophy, metabolic diseases, and connective tissue disorders.

 Nonstructural In contrast to structural curves, in a nonstructural curve the spine and supporting structures are normal. Lateral bending is symmetric and the involved vertebras are not fixed in rotated position. This type of scoliosis is a temporary condition. Generally a nonstructural curves requires no treatment.  The problem is not located in the spine itself and the curvature is the result of another problem. Examples include: Unequal leg length in which one leg is shorter than the other. Nonstructural curvatures could also develop from muscle spasms.

Pediatric Scoliosis (Scoliosis in Childhood)

Most common type of pediatric scoliosis are:

Idiopathic Scoliosis

Congenital Scoliosis       

Neuromuscular scoliosis

Scoliosis resulting from specific disorder

Idiopathic Scoliosis

The most common form of pediatric scoliosis is idiopathic scoliosis.  By definition, there is no known cause of idiopathic scoliosis.  Idiopathic scoliosis accounts for 85% of scoliosis and is categorized by age of onset: Infantile, Juvenile, Adolescent

Causes

Research as to the underlying reasons for idiopathic scoliosis has been substantial, ranging from genetic factors to disorders of bones, muscles, discs, growth abnormalities, and central nervous system causes. However, none of these factors have been conclusively shown to cause scoliosis.  An increased incidence of scoliosis has been observed in the family members of affected individuals.  This suggests a polygenic inheritance pattern. Most recently, the first gene (CHD7) associated with idiopathic scoliosis was identified. However, other genes and gene products responsible for the development of CHD7 remain unknown.

Prevalence

Scoliosis curves of greater than 10° affect 0.5-3% of the population of the United States. The prevalence of curves less than 20° is about equal in males and females. Curves greater than 20° affect about 1.5-3 in 1000 people. In curves larger than 30 degrees, female to male ratio increases to 10 to 1. Curves with the apex to the right are more common than those with a left-facing apex.

Infantile (0-3years scoliosis) scoliosis accounts for less than 1% of all types of scoliosis. This type of scoliosis is relatively minor and tends to resolve spontaneously. Because of this, observation is usually the most appropriate treatment. In severe cases, surgical treatment may be necessary.

Juvenile (3-10years) scoliosis accounts for about 15% of all types of idiopathic scoliosis. Juvenile scoliosis often requires treatment because the deformity (curve) is at a high risk of progression (worsening). In general, patients with juvenile scoliosis will require treatment, often surgery, for their scoliosis. If surgery is needed, every effort is made to delay the treatment until after the patient has reached skeletal maturity.  Braces are usually used to delay surgical treatment by slowing down the progression of the curve.   Studies have shown that the effectiveness of bracing patients with idiopathic scoliosis is directly related to the amount of time the brace is worn each day.

Adolescent idiopathic scoliosis accounts for the vast majority of (85%) of idiopathic scoliosis. Although curves are often evident at the onset of puberty, they do not become obvious until the adolescent growth spurt.  There is high degree of variability in curve progression. Risk factors for progression include: gender, remaining skeletal growth, curve location, and curve magnitude.  Remaining skeletal growth is approximated using chronological age, bone age, menarche (approximately 12 months after onset of menses, girls generally experience the most rapid stage of skeletal growth ), and other radiographic markers.

Scoliosis Symptoms

Pediatric scoliosis is usually painless. Often the curvature itself may be too subtle to even be noticed. Parents may notice abnormal posture in their growing child and the major complaint is usually a clinically apparent deformity. Most symptoms are associated with the spine being curved.

Symptoms of scoliosis can include:

·   Leaning more to one side than the other

·   A rib "hump" and/or a protruding shoulder blade

·   The opposite sides of the body may not appear level

·   A tilted head that does not line up over the hips

·   One hip or shoulder that is higher than the other, causing an uneven waist

·   In developing girls, breasts appearing to be of unequal size

·   Unequal distance between arms and body

·   Clothes that do not "hang right," i.e., uneven hemlines

·   Walking with a rolling gait

With curves of greater magnitude, prolonged sitting or standing may lead to muscle fatigue and this can sometimes cause pain. However, pain associated with mild scoliosis is very unusual. Mild scoliosis is usually detected by the pediatrician or during a school screening test.

School Screening

School screening programs for scoliosis began in the 1940s.  The effectiveness of screening is debated.  Some experts argue that screening tests are not accurate and depend too much on the skill of the examiner.  However, the American Academy of Orthopaedic Surgeons recommends that girls be screened twice, at ages 10 and 12, and that boys be screened once at 13 or 14.

Adam’s Forward Bend Test: The screening test most often used in schools and in the offices of physicians is called the forward bend test in which the child bends forward, dangling the arms, with the feet together and knees straight. The curve of structural scoliosis is more apparent when the patient is bending over, and the examiner may observe an imbalanced rib cage (with one side being higher than the other) or other deformities.

Inclinometer (Scoliometer)

An inclinometer (Scoliometer) measures distortions of the torso. The patient is asked to bend over, with arms dangling and palms pressed together, until a curve can be observed in the thoracic area (the upper back). The Scoliometer is placed on the back and used to measure the apex (the highest point) of the curve. The patient is then asked to continue bending until the curve in the lower back can be seen; the apex of this curve is then measured.

Physical Examination

Physical examination of a patient with scoliosis includes evaluation of trunk shape, trunk balance, neurologic system, limb length, skin markings, skeletal abnormalities and pubertal development, and onset of secondary sex characteristics, such as pubic hair growth and breast development.

Radiographic Evaluation

Initial radiographic assessment of spine should include standing full-length spine posterior-anterior and lateral x-ray film. Posterior-anterior (front-back) x-ray are taken from the rear in order to lessen the radiation dose to the breast tissue in the adolescent female. Lateral (side profile) x-rays are taken from the side. X-rays are taken in standing position in order to evaluate the balance of the patient’s spine.

Full-length standing spine x-rays are the standard method for evaluating the severity and progression of the scoliosis.  In some patients, lateral bending x-rays are obtained to assess the flexibility of the curves. In growing individuals, serial radiographs are obtained at 3-12 month intervals to follow curve progression. In some instances, MRI investigation is requested.

The standard method for assessing the curvature quantitatively is measurement of the Cobb angle, which is the angle demonstrating the magnitude or severity of the curve.  The Cobb angle is measured in degrees of curvature. For patients who have two curves, Cobb angles are measured for both curves.

Treatment of Adolescent Idiopathic Scoliosis (AIS)

The three basic treatment options for AIS include: observation, non-operative treatment, and surgical treatment.

Observation

Observation is the treatment of choice when the curvature of the spine is minimal (minimal curve is somewhere between 20 and 30 degrees, depending on the age of the patient and the stage of skeletal development).  Patients should visit their physician on a frequent basis so that the progression of the curve can be monitored over time.  This is done approximately every 6 months until skeletal maturity is reached.  With curves greater than 30 degrees, more aggressive scoliosis treatment is usually required.  If a curve begins to progress rapidly, a non-operative or operative treatment may be required.

Non-Operative Treatment

The goals of non-operative treatment are to prevent curves from progressing, but this type of treatment does not correct scoliosis. Electrical stimulation, biofeedback, and manipulation have been tried, unsuccessfully, to treat adolescent idiopathic scoliosis. Present non-operative treatment consists mainly of casting and bracing, with bracing being the more common alternative.

Exercise
Previous studies have not found that exercise straightens existing curves or prevents progression; stretching exercises may be beneficial in children whose scoliosis is due to uneven leg lengths or a shortened tendons. For anyone, exercise has many health benefits and is important for maintaining strength and muscle tone and stabilizing weight.

Brace

The primary non-operative treatment method used today is orthotics, also called bracing. Braces will help control any worsening of moderate curves of 25-40 degrees, but will do little to correct an existing deformity. Bracing is most effective for scoliosis treatment when used in children that are rapidly growing.  Again, the main concept of bracing is to prevent the progression of the scoliotic curve, and many experts have questioned whether a brace is any better than nature in halting the progress. Early studies have found bracing to be successful in halting the progression of a scoliotic curve in only 50% of cases.

Numerous types of braces are available today. Full torso braces called the Milwaukee or Boston brace are two very commonly used braces. This type of brace is periodically adjusted for growth. The brace needs to be worn 23 hours a day with relief only during bathing and exercise. Molded braces called thoracolumbar-sacral orthoses (TLSOs or the Boston brace) come up to beneath the underarms and can be fitted to be worn close to the skin so that they don't show under clothes. Patients are still urged to wear these braces 20 hours a day; although wearing them for 16 hours a day may still be beneficial. The Charleston Bending Brace is worn only at night, although some physicians question its value.

Compliance is a major problem with bracing because it is cosmetically unappealing and uncomfortable to the patient. In one study, only 15% of patients wore the Milwaukee brace as directed. This brace is particularly difficult to endure. Young people often refuse to wear even the newer braces.  Emotional support from family and professionals is extremely important during this process. If there is significant progression of a curve, it may lead to surgical intervention despite non-operative treatment.

Operative Treatment

The primary objectives of operative treatment of AIS are to straighten the spine as much as possible, balance the torso and pelvic areas, and maintain correction by achieving a solid arthrodesis/fusion. Fusion (joining together) the vertebrae along the curve is supported with instrumentation (steel rods, hooks, and other devices) attached to the spine.

Spinal fusion is the most widely performed surgery for correction of scoliosis. In this procedure, bone (either harvested from elsewhere in the body (autograft), or donor bone (allograft)) is grafted to the vertebrae so they will form one solid bone mass and the vertebral column becomes rigid. This prevents worsening of the curve at the expense of spinal movement. This can be performed from the anterior (front) aspect of the spine by entering the thoracic or abdominal cavity, or performed from the back (posterior). A combination of both is used to correct severe curves.

Modern spinal instrumentation involves a combination of rods, screws, hooks, and wires.  This type of instrumentation allows stronger, safer reinforcement of the spine than the old Harrington rod.  Modern spinal fusions generally have good outcomes with high degrees of correction and low rates of failure and infection. Patients with fused spines and permanent implants tend to lead normal lives with unrestricted activities when they are younger.  However, it remains to be seen whether those that have been treated with the newer surgical techniques will develop problems as they age. At this time, it is evident that they are able to participate in recreational athletics, have natural childbirth, and are generally satisfied with their treatment.

In cases where there is residual significant deformity resulting in a rib hump, it is often possible to perform a surgery called "thoracoplasty" in order to achieve a more pleasing cosmetic result. This procedure may be performed at any time after a fusion surgery, whether as part of the same operation or several years afterwards. Sometimes it is impossible to completely straighten and untwist a scoliotic spine, and it should be noted that the success of correction will depend on the extent to which the fused spine still rotates out into the ribcage.

Complications
The complications of surgery for scoliosis include, but are not limited to, the following:

Bleeding This is controlled by cauterizing bleeding vessels during the operation, and by use of a cell-saver device, whichallows the return of lost blood back to the patient at the conclusion of the operation. In addition, if it is anticipated that a patient will lose a significant amount of blood, there is a high likelihood for need of blood transfusion.

Infection  This is a risk whenever the skin is cut for any operation, as the skin is the single greatest barrier to infection in the body. Sterile technique are used, and the patient is given IV? antibiotics before the operation, and for 24 hours post-operatively.

Nerve injury   This can range from minor, such as transient and localized numbness from compression of a nerve that supplies sensation to the front of the thigh, to major, including paralysis. The risk of major neural injury is well under 1%, but it is not zero, so it is essential to have an open and honest dialogue with your surgeon about this. The electrical activity of the nerves that transmit signals for sensation and muscle action through the spinal cord is monitored during the procedure. This gives feedback to the surgeon so that the necessary step(s) can be taken to remedy the problem.

Pseudarthrosis  This means that occasionally - up to 1% of the time in children (but higher in adults) - the fusion does not take, or the vertebra do not stick together completely. It can take several months or a few years to become apparent. The patient may complain of persistent back pain, there may be progression of the scoliosis after the operation, or the implants may fail (when the fusion does not take, there is motion that over the long term will cause the metal to fatigue and ultimately break). The treatment is exploration of the spine, addition of bone graft, with replacement of the implants.

Postoperative Therapy
Breathing and coughing exercises to rid the lungs of congestion must be performed shortly after the procedure and continued through the recovery process. The patient is usually able to sit up within a day after the operation, and most patients can move on their own within a week. A brace may be necessary, depending on the procedure.  The average hospital stay following surgery for AIS is 4-5 days.

Congenital Scoliosis

Congenital scoliosis is curvature of the spine caused by the malformation of vertebra or vertebral segments.  This malformation is caused by an insult to the embryo during development. Although the vertebral malformation is present at birth, clinical deformity may only become evident with growth. Deformities range from the entirely benign to the severely debilitating.  Congenital malformations are relatively rare, but the true incidence of congenital scoliosis is unknown because some malformations are so well masked that they are never identified. There is, however, an association between congenital vertebral anomalies and other malformations. This is because the spine and other major organs develop during the same intrauterine period. Therefore, in patients with congenital scoliosis, it is common to see other congenital malformations such as heart problems, kidney or bladder problems, and spinal cord malformations.

There are three basic types of congenital malformations of the vertebral column: failure of formation, failure of segmentation, or a combined malformation. Failure of formation occurs when part of a vertebra did not form.  This is often called a hemivertebra (half vertebra). A hemivertebra creates an imbalance in the spinal column, forcing the spine to curve as the child grows.
   Failure of segmentation occurs when part or all of the two or more vertebral bodies fail to separate during embryologic development.  This results in malformations such as block vertebra (where multiple vertebra are fused together), or as a unilateral bar vertebra (when one side of the vertebra fuse together), which produce a growth tether of the spine.

Finally, when these malformations occur in combination, a combined defect results.  This combined malformation can cause the resulting scoliosis to progress in very rapid manner. A great majority of patients have combined formation and segmentation defects.

Individualized treatment plans are made based on risk of curve progression during growth.  Treatment plans can cover a wide range of options, including observation, bracing, and surgical intervention.  The goal of all treatment plans is to allow the child to reach skeletal maturity so that the spine can grow as much as possible without allowing the spine to become grossly imbalanced.

Neuromuscular scoliosis

Neuromuscular scoliosis is the curvature of the spine that is caused by various neuromuscular conditions.  These conditions include: cerebral palsy, muscular dystrophy, polio, spinal muscular atrophy, and post spinal cord injury conditions, in addition to other diseases.  Patients affected with these conditions often develop scoliosis during childhood. These curves have a high risk of progression and risk of significant cardiopulmonary complication.

Treatment plans are usually individualized and depend on the patient’s clinical symptoms (pain, sitting balance) as well as the location and severity of the deformity.  Many patients with neuromuscular scoliosis undergo spinal fusion so they can maintain upright sitting position in a wheelchair and have better lifestyle.

Scoliosis resulting from specific disorder

Pediatric scoliosis is also commonly associated with other disorders such as: neurofibromatosis, Marfan’s syndrome, infection, myelomeningocele, tumor, achondroplasia, and osteogenesis imperfecta.

Adult Scoliosis

Adult scoliosis occurs in persons over the age of 18 who are skeletally mature.  Adult scoliosis can be divided into 2 main categories: 1) progression of childhood scoliosis, or 2) degenerative scoliosis.  The prevalence of both residual childhood scoliosis and degenerative scoliosis is approximately 6% in adults over the age of 50. Adult scoliosis is generally more symptomatic than adolescent idiopathic scoliosis.  Back pain is the most common complaint of patients with adult scoliosis.  Other concerns include: cosmetic appearance, possible pulmonary compromise (trouble breathing), and pain caused by associated spinal stenosis or osteoporotic changes in the spine.  Because of this, patients with adult scoliosis typically seek medical treatment due to the appearance of their deformity, a worsening or progression of their deformity, and back or leg pain caused by the scoliotic deformity.   

Progression of Childhood Scoliosis

The most common type of scoliosis that progresses from childhood into adulthood is idiopathic scoliosis.  However, congenital and neuromuscular scoliosis can also affect adults.  Patients with adult idiopathic scoliosis have had scoliosis since adolescence.  However, once skeletal maturity is reached, these patients are said to have adult idiopathic scoliosis.  It has been reported that large curves (those greater than 50 degrees) in adolescents have a significant chance of continuing to worsen into adulthood.  Like adolescent idiopathic scoliosis, the scoliotic curve can be in the thoracic, thoracolumbar, or lumbar regions of the spine. While adolescents with scoliosis are typically treated for progression or worsening of their curve, their adult counterparts are usually treated for pain.  Seeking treatment for back pain is typically an age-related phenomenon. 

Adults under the age of 40 generally seek treatment because of a worsening of their curve or because of their cosmetic appearance.  While these patients may experience back pain and muscle fatigue, pain is not usually their chief complaint, as their spines have not yet developed age-related degenerative changes. 

Adults over the age of 40 usually seek treatment because of back pain related to their scoliosis.  The pain experienced by adult patients with idiopathic scoliosis can be caused by nerve compression or muscle fatigue.  Age-related, degenerative, and osteoporotic changes in the spine can be accelerated by the pre-existing abnormal curvature of the spine.  As the spine ages, it becomes less flexible and an adult may not be able to maintain good overall trunk balance.  This can lead to decompensation or imbalance of the head relative to the pelvis. Decompensation can also cause pain due to muscle fatigue as the muscles attempt to hold the imbalanced spine in normal alignment.  Although patients with idiopathic scoliosis have the same chance of developing back pain as adults without scoliosis, patients with idiopathic scoliosis tend to have more severe, reoccurring pain.  Certain types of curves (lumbar or compensatory lumbosacral curves) are associated with increased pain.  Patients with degenerative changes associated with idiopathic scoliosis or patients who have developed a compensatory lumbosacral curve are more likely to note low back pain with referred pain in the legs.   Radicular leg pain or neurogenic claudication (severe leg pain that occurs when walking and improves when the patients sits) is not as common in patients with idiopathic scoliosis compared with those with degenerative scoliosis.

Degenerative Scoliosis

Degenerative, or de novo, scoliosis is usually seen in adults over the age of 40.  It occurs in a previously straight spine.  Degenerative scoliosis is seen equally in both males and females.  The scoliotic curve is caused by degeneration of the intervertebral discs and facet joints.  The degeneration of these elements can cause instability in the spinal column leading to rotation, lateral listhesis (sliding of the vertebrae to the side), spondylolisthesis (sliding of one vertebrae over another to the front), kyphosis (humpback), or osteoporosis with vertebral compression fractures.  Unlike adult idiopathic scoliosis, with its array of curve patterns, the degenerative scoliosis curve typically occurs in the lumbar spine.  Although the curve is not located in the upper regions of the spine, it can still cause the vertebrae above the curve to rotate and slip out of alignment.  As patients age and develop further degeneration of the vertebrae and surrounding structures, their curves may progress at a faster rate.  Adult degenerative curves are typically of smaller magnitude than those seen in adult idiopathic scoliosis. Degenerative curves can worsen as much as 3.3 degrees per year.  

Because degenerative-type scoliosis causes the vertebrae to rotate and translate from their normal positions and the disc spaces to collapse, the nerves exiting the spinal column can become impinged.  Compression of the nerve roots usually occurs in the concavity of the curve.  Leg pain resulting from degenerative scoliosis is usually from nerve-root impingement due to disc height decrease (seen as the spine ages and the discs become smaller and more brittle), disc degeneration, enlarged, arthritic facet joints, or vertebral slippage.  All of these problems allow less room for the nerve roots to exit the spinal canal.  Because of this, the most common reason for patients with degenerative scoliosis to seek medical care is pain.  Although back pain and fatigue may be present, the most common complaint is radicular pain radiating down the legs or neurogenic claudication.

          

Diagnosis

As with childhood scoliosis, it is extremely important for patients with adult scoliosis to receive an accurate diagnosis so that a treatment plan can be developed.  Radiographic and a thorough neurologic examination are two key components of a scoliosis evaluation.

Radiographic Evaluation

In order to determine the magnitude of a scoliosis curve and the region in which it occurs, full spine x-rays (front and side views) of the standing patient must be examined.  This is very similar to the x-rays taken for childhood types of scoliosis.  X-rays enable the physician to fully evaluate the overall balance from both the front and side views.  The physician will also measure the height between the vertebrae (disc height) and look for the development of osteophytes (bone spurs).  Additional x-rays of the patient bending to the side are also obtained to help determine the flexibility of the part of the spine which is curved.  In adults it is common to obtain several other tests in addition to plain x-rays.  CT scans, MRI scans, and/or discography are other types of studies that can help the physician to best evaluate a scoliotic deformity.  The goal of these types of tests is to determine the extent of degeneration of the vertebrae and vertebral discs and the presence and extent of spinal stenosis.  MRI is usually adequate to evaluate these details, but sometimes a CT myelogram is necessary to obtain more details with regard to neural structures. 

Physical Examination

Adults with scoliosis need to undergo a physical examination.  Details of the patient’s entire medical history will be examined.  Specifically, the patient will be asked about their symptoms, treatment history, and if there is a family history of scoliosis.  Physically, patients will be examined to determine if there is any limitation of normal movement, pain, numbness, loss of normal extremity reflexes, muscle weakness, and for other signs of any neurological damage.  Patients will be examined to see if there is a difference in leg length, shoulder height, or other signs of trunk malalignment.

Treatment Options

The treatment of adult scoliosis is complex and needs to be individually managed for every patient.  Generally, the goals of treatment of adult scoliosis are to control pain and preserve or increase function.  Sometimes, adult scoliosis does not need to be treated at all.  If the curve is small and is not causing significant pain or dysfunction, observation of the curve (to see if it worsens over times) may be the only treatment necessary.  Adult scoliosis can be treated non-operatively or surgically.

Non-surgical Treatment

The first line of treatment for many cases of adult scoliosis is non-surgical treatment.  There are many different types of non-surgical treatment.  These include:  1) medications (non-steroidal anti-inflammatory medications to reduce inflammation and relieve pain, such as ibuprofen and XXX) 2) epidural or facet injections (to deliver anti-inflammatory medication or numbing medication directly to the affected area), 3) physical therapy (to help maintain strength and flexibility and prevent further progression of osteoporosis), 4)  pool therapy (stretching and exercising in the water to provide conditioning),  5)  bracing (to help eliminate motion and provide pain relief, not to correct the scoliosis).  These treatments may be used alone or in any combination.  Non-surgical treatments do not “cure” adult scoliosis, but rather enable the patient to manage the pain and to stay functional.  Non-operative treatments are generally very successful. 

Surgical Treatment

Surgical treatment for adult scoliosis typically occurs when non-operative treatments are unable to provide adequate pain relief, the curvature of the spine is large or worsening over time, the patient is experiencing neurological problems (leg weakness or bowel/bladder problems), or the curve is causing the patient to have cardiopulmonary (heart and lung) problems.  Surgical treatments for scoliosis are varied and depend on a wide variety of factors. 

The major surgical intervention for treatment of adult scoliosis is spinal fusion.  Spinal fusion is a procedure in which the vertebrae of the spine are fused together.  This is done using various types of instrumentation, typically screws and wires, and bone graft.  The principles for spinal fusion surgery in adults with scoliosis are similar to those used for childhood scoliosis.  Idiopathic curves tend to require the fusion of more vertebral levels than degenerative curves, chiefly because degenerative curves tend to be shorter, more limited curves.  Most people being surgically treated for degenerative scoliosis need to have other procedures in addition to spinal fusion.  This is because the pain caused by degenerative scoliosis is from accompanying spinal stenosis and not the scoliosis itself. 

Sometimes, simply realigning the spine can give compressed or impinged nerve roots the room they need to provide pain relief.  Sometimes, however, realigning the spine is not enough.  In this case, to alleviate the symptoms caused by spinal stenosis, a decompression procedure is performed.  Lumbar decompression allows the nerve roots to have more space.  To correct stenosis, a procedure called a laminectomy is performed.  A lumbar laminectomy involves removing a piece of the bone surrounding the nerve as it exits the spine to provide more room for the nerve so that it is not impinged or compressed.

The goal of spinal fusion surgery is to obtain a balanced (both side-to-side, back-to-front/profile balance) and stable spine, and to decompress any nerve roots that are impinged.  It is imperative that the patient and surgeon have the same expectations and goals before surgery is undertaken.  Although spinal decompression and fusion is a successful procedure, it does not provide complete pain relief.  Studies have shown that spinal fusion for adult scoliosis provides a decrease in pain severity in 70% of patients but does not improve the frequency with which the pain occurs.   

The extent of surgical correction required in patients with adult scoliosis depends on several factors.  In cases where the curve is very mild and there are no signs of spinal instability, decompression alone can be considered.  Patients with larger curves must undergo spinal fusion in addition to the decompression. 

Generally, adults between age 20 and 35 with residual childhood scoliosis have not had time to develop severe degenerative changes associated with age.  Patients in this group can be treated very similarly to adolescent patients with idiopathic scoliosis.  In this group, surgery is usually undertaken if the curve has progressed to greater than 50 degrees and pain generated from the curve is not adequately controlled by non-operative treatments.

Patients over 40 years of age who have developed either severe degenerative changes in their spine, are grossly imbalanced, or have developed a compensatory lumbosacral curve may require more extensive surgery, depending on their coronal (side to side) and sagittal (front to back) balance. 

Spinal fusion surgery is a very individualized procedure.  For each patient, the surgeon must determine which and how many vertebrae to fuse.  To make this decision, the surgeon accounts for many factors, including, but not limited to, the magnitude of the curve, the number of levels affected by the scoliosis, the region affected by the scoliosis, the translation of the vertebrae, quality of vertebral bone, and levels requiring decompression for spinal stenosis.

An additional decision that must be made is whether to use an anterior (front), posterior (back), or combined surgical approach. Generally, adults with flexible thoracic or thoracolumbar curves can be treated with posterior spinal fusion alone. 

For adults with moderate thoracic or thoracolumbar curves, anterior surgery can provide balanced correction of the scoliotic curve.  Anterior procedures serve to “loosen” up the front of the spine by removing intervertebral discs and straighten it by inserting bone grafts.  This allows the surgeon to achieve greater correction of the deformity from the back.  Anterior release can improve overall correction of the scoliotic deformity and also improve fusion rates. 

Adults with severe thoracolumbar or lumbar curves, rigid curves, gross coronal or sagittal imbalance, or severe compensatory curves will benefit most from combined posterior and anterior surgery.

Generally, scoliosis can be corrected from the back and adequate decompression of nerve roots can also be achieved in this manner.  Posterior surgery lasts approximately 3-6 hours and requires 5-7 days of postoperative hospitalization.

Risks

Spinal fusion, like any other surgical procedure, is not without risks.  Possible complications include, but are not limited to:  persistent pain, infection, neurologic injury, prominent hardware, instrumentation pull-out, urinary tract infection, stroke, pneumonia, deep venous thrombosis (DVT), pseudoarthrosis (vertebrae do not fuse together), and further progression of the deformity.  In general, complications are uncommon.  Risks are greater with complex deformities or revision surgeries.  Pseudoarthrosis, or failure of the bones to fuse, is the most common complication associated with adult scoliosis surgery.  The rate of pseudoarthrosis varies between 5-28%.  Infection at the surgical wound is a complication that arises approximately 1-8% of the time.