Adolescent idiopathic scoliosis is a condition in which the spine is curved in one or more planes [Figure 1]. This type of curve is distinguished from curves that have a forward orientation and appear as a hump, a condition known as kyphosis [Figure 2].
Figure 1: Anteroposterior (AP, or rear) view of the spine (standing) demonstrates scoliosis in the thoracic and lumbar spine.
Figure 2: Lateral (side) view of the spine (standing) demonstrates kyphosis in the thoracic spine.
The term “adolescent” describes patients ranging in age from 10 to 18. “Idiopathic means that there is no known cause for this condition,” explains Oheneba Boachie-Adjei, MD, Chief Emeritus of the Scoliosis Service at Hospital for Special Surgery (HSS). “However, recent research has revealed genetic markers for adolescent idiopathic scoliosis that can show us which curves are likely to progress and require treatment.” (Other forms of scoliosis in adolescence include congenital scoliosis, in which spinal deformities are present at birth, neuromuscular scoliosis, and skeletal dysplasia.)
Found more frequently among girls than boys, adolescent idiopathic scoliosis is the type of scoliosis seen most frequently by spine surgeons and makes up 80% of all spinal deformities.
Typically, adolescent idiopathic scoliosis is first noted by the young person’s pediatrician, family member, or school nurse. As an initial screening method, healthcare professionals use the Adams forward-bending test to look for the presence of any asymmetry of the torso or shoulder blades, or protrusion of the shoulder blades [Figure 3].
Figure 3: This photo shows a pronounced curve on an Adams forward-bending test.
A scoliometer is used to measure the amount of trunk inclination (the curve) or rotation (twisting of the spine). Adolescents with a measurement of 7 degrees or greater are referred to an orthopedist for further evaluation. Adolescent idiopathic scoliosis rarely causes pain; therefore the presence of back pain in a young person with scoliosis may be a sign of another condition.
To further assess the curve, x-ray images are taken from the front and side views [Figures 4 & 5]. Side-bending x-rays may also be taken to assess the flexibility of the curve or curves. Sometimes these images reveal two curves: the first curve to appear in the spine (the primary curve) and the compensatory curve that the patient develops in an effort to maintain an erect posture.
Figures 4 & 5: Anterior/posterior (left) and lateral (right) x-rays showing a scoliosis curve
from the back and side, respectively.
Treatment for adolescent idiopathic scoliosis is determined by the degree of the curve at diagnosis and anticipated progression of the curve. For curves measuring less than 25 degrees, the orthopedist may recommend frequent monitoring to see if additional intervention becomes necessary. Young people with curves between 25 and 45 degrees may be candidates for treatment with bracing. While bracing does not correct the curve, it has been shown to stop progression in up to 75% of patients. Bracing is considered a success when progression is halted and maintained within 6 degrees of the original measurement of their curve.
Candidates for bracing are generally pre-pubescent and skeletally immature as measured on the Risser test (a staging system that measures maturation of the hip bone). A measurement of 0 to 2 indicates that the growth is expected to continue. Skeletal maturity is achieved in female patients who reach a level of 4 and in male patients who have reached a level of 5. The absence of any change in height over a period of 6 to 12 months is another indicator of skeletal maturity.
In most cases, patients wear a brace for 22-23 hours a day, removing it for hygiene and sports activities. However, some patients may only require the use of a brace at night.
A variety of braces are available and selection is based on how many curves are present and where on the spine the curve or curves are. Some models provide support at the pelvis, front, back, and neck, where others provide support throughout the torso and underarms.
While many braces are rigid, flexible braces have been developed in recent years. This type of brace, which is only appropriate in patients with single curves, is worn as a vest and allows the patient to participate in some sports activities [Figure 6].
Figure 6: A patient wearing a rigid, flexible brace, allowing participation is some sports activities.
Patients continue to wear the brace until skeletal maturity is reached. A weaning process follows in which the number of hours the brace is worn per day is gradually reduced over a period of six months to a year. This allows the supportive muscles in the back and trunk to become stronger after a period of inactivity. Physical therapy is also recommended, both during bracing and weaning.Operative Treatment
Patients with curves that continue to progress beyond 50 degrees, either with or without bracing, generally require surgical intervention.
The most common type of surgery is a posterior spinal fusion with instrumentation. In this procedure, the orthopedic surgeon makes an incision from the back of the body, and essentially welds the vertebrae together using bone chips taken from the spine or elsewhere in the body, or from a bone bank. Hooks, screws, or other instrumentation is used to hold the spine in alignment during the healing process, which takes six to twelve months in an adolescent. Once the fusion is complete, the instrumentation no longer serves a function but is left in place to avoid the need for additional surgery [Figures 7 & 8].
Figures 7 & 8: Postsurgical posterior (left) and lateral (right) x-rays in the patient seen in Figures 4 & 5: results achieved with a posterior approach.
Depending on the nature of the curve and its location, the orthopedist may need to perform a fusion from both the front (anterior), the back, or both front and back of the body, a procedure that may be done as a single operation or in stages.
Figures 9 & 10 (top): Presurgical posterior (upper left) and anterior (upper right) x-rays -
scoliosis requiring anterior approach.
Figures 11 & 12 (bottom): Postsurgical posterior (lower left) and lateral (lower right) x-rays -
results achieved with an anterior approach.
Some patients may also be candidates for thoracoscopic surgery, in which incisions are made from the side of the torso. As with the posterior and anterior approaches, instrumentation corrects the curve and the rotation of the spine. “The thorascoscopic approach offers the advantages of smaller incisions and shorter fusions, which in turn preserves more mobility in the spine following surgery,” Dr. Boachie explains. Thoracoscopic surgery is appropriate primarily for larger and rigid thoracic curves that require anterior release to increase flexibility.
But, Dr. Boachie says, “with the introduction of pedicle screws, posterior-only surgery has become the main method of treatment for most curves, large or small.”
Figures 11 & 12: Photos of an adolescent girl with adolescent idiopathic scoliosis in the thoracic section of the spine,
before (left) and after (right) surgery.
Fusion surgery generally yields very good results, with a correction rate of between 60 to 100%, depending on curve flexibility and location, according to Dr. Boachie.
Good cosmetic results are a balanced spine, leveled shoulders, and the reduction or elimination of any rib hump. “These young people, who are usually otherwise healthy, tend to tolerate the surgery very well,” Dr. Boachie adds. Rare complications can include infection and spinal cord abnormalities or injury. However, at HSS, multiple precautions are taken during surgery to protect the patient, including administration of antibiotics during surgery to help guard against infection and continuous monitoring of sensory and motor function of the spinal cord.
Following surgery, most patients remain in the hospital for four to seven days (slightly longer for those who undergo combined anterior/posterior procedures) and are on their feet in two days. Pain medication is continued for a few weeks and the majority of young people are back in school within four to six weeks. Some exercise, such as swimming and aerobic exercise, may be resumed within three months and patients may return to full activity within six months. Spinal fusion does result in some loss in range of motion; the degree varies depending on the site and length of the fusion.
Q: My 14-year-old daughter has just been diagnosed with idiopathic scoliosis. The doctor measured the curve on x-ray to be 20 degrees and said her bones are nearly fully grown. She does not have pain and the curve is hardly noticeable but we are concerned that it will continue to increase and become a big problem later in life.
A: Once your daughter is skeletally mature, when bone growth is complete, the curvature of the spine in idiopathic scoliosis will not increase and is unlikely to be a problem. she should continue to be evaluated every 2 to 5 years to follow the curve .
Q: I've heard that electrical stimulation can be used to correct scoliosis. Why isn’t my physician recommending this?
A: While use of this technique has been reported, there is no good clinical evidence to suggest that it offers any benefit to patients with idiopathic scoliosis. It is currently not considered a standard of care.
Q: I'm scheduled to undergo surgery for scoliosis and am worried about damage to my nervous system. What are the risks of injury?
A: When performed by experienced orthopedic spine surgeons, surgical treatment for scoliosis is considered very safe. Maintaining and protecting nervous system function is one of the surgeon’s highest priorities. In general, for uncomplicated adolescent idiopathic scoliosis, the reported risk of nerve injury with surgery is between 0.7-1%; in adults the rate ranges between 1 and 5%. Intra operative spinal cord monitoring will help detect early changes in cord function during surgery.
Q: What are the chances that additional surgery will be required for a 15-year-old adolescent undergoing a first surgical treatment for scoliosis?
A: If spine surgery has been properly performed in an adolescent, the chance that the patient will require revision surgery in the short to medium term is minimal. More than 98 percent of patients do well. Surgical complications are quite rare, and most patients leave the hospital within a week after surgery without pain or other problems with wound healing, or the instrumentation used to correct the spinal curve. The need for further surgery in the future will depend on the type of instrumentation that was used and the sagittal (sideways) alignment of the spine. Location of the area in which instrumentation was placed is also significant. Formerly, revision surgery in the long term was more common in patients with long fusions to the lower portion of the lumbar spine (the vertebrae closest to the pelvis). It appears that the current use of current segmental instrumentation systems that take into account the restoration and maintenance of spinal alignment is reducing the chance that (longer term) revision surgery will be necessary.
Q: What are the advantages of an anterior versus a posterior procedure?
A: The terms posterior (from the patient’s back) and anterior (from the front and side of the body) refer to the approach the surgeon takes in reaching the area of the spine to be treated. Most curves can be treated with a posterior procedure in which the surgeon uses segmental instrumentation and fusion. This type of surgery generally works best for thoracic curves and for double curves. A posterior approach is easier for the surgeon and offers the advantage of allowing two rods to be placed which obviates the need for external immobilization with a brace or other device. Traditionally, some special curves - such as thoracolumbar and lumbar deformities - have been treated with anterior approach because it offers the advantage of fusing the fewest levels possible, and the ability to de-rotate the spine and provide three-dimensional correction of spinal deformity. Spine surgeons have applied anterior instrumentation to thoracic curves, but this is not a popular practice these days.
If you would like more information about treatment of adolescent idiopathic scoliosis at HSS, please visit the Physician Referral Service or call 1.877.606.1555.
Summary by Nancy Novick; images by the HSS Department of Radiology and Imaging