Scoliosis is often defined as simply a frontal plane deformity of the spine >10°. The deformity is much more complex, however, and includes significant transverse and sagittal plane components.
This type of scoliosis can also be described as “functional” because it is secondary to some other problem. The scoliosis usually resolves when the underlying problem is corrected. The scoliosis is usually flexible and nonstructural. There are no bony changes, and the rotational elements are minimal.
Leg length discrepancy Differences in limb length produce a transient functional scoliosis. This type of scoliosis seldom becomes rigid or structural, presumably because the scoliosis is present only when the child is standing on both feet. Thus with lying, sitting, and walking, the spine is straight. The fear of causing a structural scoliosis or other back problems is not a valid reason for ordering a shoe lift or for performing limb length equalization procedures.
Muscle spasm Scoliosis may be the presenting sign for several inflammatory or neoplastic disorders. The spinal curvature often functions to relieve discomfort. For example, the back is curved to reduce pressure on a nerve from a herniated disc. Management is directed at the underlying disorder. Scoliosis will disappear once the underlying problem is corrected.
History Inquire about the age of onset, progression, and previous management. A family history of deformity or pain is important as both run in families. Painful scoliosis in the child suggests an inflammatory or neoplastic basis for the scoliosis.
Screening examination Start with a screening examination. Look for conditions such as Marfan syndrome or the café au lait spots of neurofibromatosis. Assess the child’s limb lengths and gait, and perform a neurological examination.
School screening The value of school screening is controversial. The advantage is the earlier detection of deformity. The disadvantage is the large numbers of children with schooliosis, those with minimal truncal asymmetry that are referred to physicians, often studied radiographically, and subjected to the anguish of having scoliosis. Proposals to be more efficient have included establishing a threshold of 7° scoliometer reading and biannual screening.
Back examination Note differences in shoulder height, scapular prominence, and pelvic symmetry. Ask the patient to bend forward. Be concerned about stiffness or a list, as these suggest an underlying neoplastic or inflammatory process.
Perform the forward bending test Visually scan each level of the spine to assess symmetry. If a “rib hump” is present, measure it with a scoliometer. This simple device measures the tilt of the rib hump. Record the displacement of the weight from the buttock crease.
Radiographs Radiographs are indicated if the scoliometer reading is greater than 7° or if progression is likely. Progression is more likely if the child is under 12 years of age, when others in the family have significant curves, or if any findings suggest that the curve may not be simply idiopathic. Radiographs should be made on 36-inch film and taken standing with shielding. A single PA radiograph is satisfactory for screening or a baseline study.
Cobb angle This method measures the level with the greatest tilt. Note the “apical vertebra,” as this defines the level of the curve. Curves greater than 10° are considered significant.
Flexibility Left and right bending studies show the rigidity of the curves. The value of these studies is controversial.
Level A general classification of the level of the curve is used for general description without regard for management considerations.
Maturity is assessed by clinical evaluation or the Risser sign.
Congenital structural defects may cause a variety of spinal curves. Such curves are often complex and may require special imaging techniques for assessment. Because these malformations are due to an abnormality of the fetal somite formation, associated lesions in the same somite are common. Thus, the finding of congenital scoliosis, especially one involving the thoracolumbar region, should prompt an ultrasound evaluation of the urinary system and consideration about syndromes such as the VACTERL association.
Note the severity, symmetry, and flexibility of the curve. Screen the child for additional disorders of the urinary and cardiovascular systems. Murmurs should be evaluated by a pediatric cardiologist. Order a renal ultrasound, as 10–20% will have congenital urinary abnormalities, some of which are life-threatening.
Imaging Study the pattern of the curve on AP and lateral radiographs of the spine and additional imaging methods for special situations. Categorize the curve pattern to assess the likelihood of progression. If the curve pattern is ambiguous, CT scans of the apical region are sometimes necessary. MR studies are indicated if neurological abnormalities are found. Plan follow-up and repeat the radiographs in 3–6 months.
Observation is appropriate when the potential for progression is uncertain. Evaluate every 3 months during the first 3 years and again during puberty when spinal growth is greatest.
Orthotic treatment of congenital scoliosis is controversial and less effective than for idiopathic curves. Congenital curves that are long and flexible are likely to respond to brace treatment.
Operative treatment The goal is to obtain a balanced trunk and spine and to prevent any neurological defects with the least disturbance in normal growth. Operative treatment is required in about half of children. Several options are available.
In situ fusion is indicated for curves due to unilateral bars or mild to moderate curves demonstrating progression. In children under 10 yo, both anterior and posterior fusions are necessary to prevent a crankshaft phenomenon.
Hemivertebra resection This procedure may be indicated for severe curves with spinal imbalanace at or below the thoracolumbar junction in young children.
Instrumentation and fusion Moderate curves in the older child may be managed by limited correction. Limited correction and careful monitoring are necessary to prevent neurological complications.
Osteotomy or resection and instrumentation These aggressive measures may be necessary for severe deformity and imbalance. Preoperative halo traction and staged correction are techniques that may reduce the risk of complications.
Hemifusion on the convex side may be considered for lumbar curves in infants or young children to provide some correction with growth.
Thoracic Insuffiency Syndrome
This syndrome may accompany congenital scoliosis. This syndrome includes rib fusions and the inability of the thorax.
Campbell and associates have developed a technique for correction. The procedure may also be used for bilateral insufficiency.
The cause of idiopathic scoliosis is uncertain. The deformity has a genetic component, as the concurrence among twins is greater than 50% and about a quarter of the daughters of mothers with significant scoliosis also have the deformity.
Progression The potential for progression depends upon the age of onset, curve severity and level of skeletal maturity, Risser sign, and status of the triradiate cartilage. .
In adults, curves <30° progress little, and curves 30–50° progress about 10° over a lifetime. Curves 50–76° progress about 1° a year.
Pulmonary function Restrictive lung disease can be detected in patients with Cobb angles >100 degrees. Increased early mortality has been demonstrated only for severe early onset scoliosis. Ventilation perfusion scans show that the concave lung is the most affected in the majority of cases. Correction of adolescent scoliosis has been demonstrated to increase vital capacity an average of 15% in short-term studies. Individuals with scoliosis have normal mortality rates.
Idiopathic scoliosis is often divided into categories based on age of onset and curve pattern.
Age of onset Onset may be described simply as early or late. Traditionally, three categories have been used.
Infantile Onset occurs in the first 3 years
Juvenile Onset at age 3 to 10 years.
Adolescent Onset at age 10 years to maturity.
Curve pattern The patterns may be described simply by location. This classification is useful for all types, independent of cause. For idiopathic scoliosis, curves are classified to facilitate management and communication.
King-Moe This classification includes five categories and clarifies which thoracic curves require fusion and the importance of the stable vertebra as the endpoint for instrumentation and fusion. Because this classification has been demonstrated to show low inter- and intra–observe reliability and limitations when utilizing modern methods of instrumentation, Lenke and associates developed a new classification.
Lenke This classification includes six curve types, a lumbar spine modified (A, B, or C) and a sagittal thoracic modified (-, N, or +), creating a total of 42 different curve types. The lumbar modified more precisely defines the position of the lumbar curve. The thoracic modified defines the sagittal alignment as being hypokyphotic, normal (curve 10°–40°) or hyperkyphotic.
Manage scoliosis by observation, bracing, or surgery. Exercises, electrical stimulation techniques, and manipulation are ineffective and should be avoided. Ninety percent of curves are mild and require only observation. The objectives of treatment are to avoid unnecessary treatment, to minimize the morbidity of required treatment, and to successfully arrest progressive curves or correct curves that cause or will likely cause disability.
Reassurance is an important part of management. Avoid the term scoliosis for mild curves, and simply refer to the deformity as a “mild truncal asymmetry.” This reduces the apprehension that is associated with the scoliosis. This diagnosis often causes apprehension, as scoliosis is usually equated with treatment either by bracing or surgery.
Indications for treatment should be individualized; however, some generalizations can be made.
Observation only is indicated for curves of less than 25°. Mature patients may be discharged or advised only if they become symptomatic. Follow immature adolescents with a radiograph every 6 months until maturity.
Brace treatment is indicated for immature patients with curves of 25°–40°. Boys may be treated with Risser 2–3 if the curve exceeds 30° and is progressive. Observe smaller curves for progression. Progression is defined as a documented increase of 5 or more degrees.
Operative treatment is usually indicated for curves >40° and mature patients with curves >50°.
Infantile scoliosis occurs in children under 3 yo. Because the deformity often is associated with plageocephaly and hip dysplasia, it is thought to be a positional deformity. Like other position deformities, spontaneous resolution usually occurs. In some cases, the scoliosis is secondary to an underlying spinal abnormality. These cases progress to become severe. Infantile scoliosis is rare in North America.
Boys with left thoracic curves are the most common group to have infantile sciolosis. Study by radiographs and measure the apical-rib-vertebral angle difference, or RVAD. If the RVAD exceeds 20°, study with an MRI, as about a quarter will show a significant neuroanatomical abnormality such as Chiari-1 malformations.
Curves with angles of <20° resolve and require only observation. Follow closely curves >20°. If curves progress and exceed 30°, manage with a brace. Curves uncontrolled by bracing that exceed 40° may require operative correction. Several operative options are available.
Rib distractors Titanium rib distraction with lumbar laminar fixation may be serially expanded for gradual reduction in curve severity.
Spinal instrumentation Instrumentation without fusion preserves growth.
Fusion Consider anterior and posterior fusion to arrest progression and prevent crankshaft deformity. Be aware that, following fusion, trunk height will be lost at about 0.07 cm per level fused times the years of remaining growth.
This form of scoliosis is identified between 3 and 10 yo. Gender ratios are about equal for the younger patients, but girls become predominant toward puberty. About two-thirds of the curves are progressive. Most require bracing.
Measure the Cobb angles. For children with a Cobb angle >20°, study with a full spine MRI, as 20–25% will show a significant spinal abnormality such as Chiari I malformations or tumor. Hypokyphosis with values <20° suggests a poorer prognosis and complicates orthotic management.
Follow for progression. A few curves resolve spontaneously. Institute orthotic management for progressive curves that exceed 20°.
Bracing Manage curves with an apex below T7 with a TLSO. A Milwaukee brace is necessary for more proximal curves. Considering the long duration of bracing necessary, balance brace time with tolerance. Avoid bracing for too many years, as the child must endure many years of brace treatment as well as the final surgical correction.
Operative correction is indicated for curves exceeding 40°. Anterior and posterior fusions are necessary for young children to prevent the crankshaft deformity. Be certain to correct or maintain normal sagittal alignment. Instrumentation without fusion may be considered in young children, as described for the infantile form.
Idiopathic scoliosis with an onset after age 10 years is the classic form.
Bracing usually slows or arrests progression of spinal curvatures in immature patients with curves between 25° and 40°. Brace curves with documented progression above 25° or curves above 30° when first seen.
Bracing options Select the orthosis based on the level of curve and the anticipated tolerance of the patient. The most effective bracing types and protocols are also the most restrictive and cause the greatest psychosocial disability. Select a balance that is best for the patient.
Nighttime braces are best tolerated, but effectiveness is contoversial. The Charleston bending brace is most widely used. The brace is worn only at night, allowing the child freedom during the day.
TLSO brace It is appropriate for curves with an apex in the midthorax and below. The Boston brace is prefabricated with custom pads applied by the orthotist. Most include a 15° lordosis correction. The brace may be worn on a 16- to 23-hour-per-day protocol.
Milwaukee brace For upper thoracic curves, the Milwaukee brace may be necessary. This brace is the most restrictive and is compatible with limited activity.
Introduce the brace over a period of several weeks. Encourage acceptance as quickly as possible. Discomfort in the brace should be corrected by making necessary modifications early. Continued discomfort reduces compliance, increasing the risk of bracing treatment failure. Modifications in the brace will correct this problem. Encourage normal activities while being braced.
Improving acceptance The bracing schedule may be tailored to the patient. Some patients are already at or beyond their tolerance limits. It may be best to maintain a relationship with the patient and family and to follow the patient without treatment. If the curve is advanced, it may be best to elect an operative option earlier than is normally appropriate.
Initial response should show a reduction of the curve by >50%.
Follow-up Schedule follow-up visits every 6 months to assess fit, size, compliance, and curve progression. Obtain a standing PA radiograph out of the brace to assess progress.
Dealing with compliance The patient should participate in most prebracing activities. All of these problems further complicate an already difficult time in life. The physician must not exceed the “tolerance limit” of psychological stress on the patient. If this tolerance limit is exceeded, the patient will become noncompliant and may not return for follow-up. He or she may simply ignore the problem or seek nonconventional methods of treatment that are less demanding.
Discontinue bracing about 2 years post-menarcheal or Risser 4 for girls and Risser 5 for boys. Progression while bracing may indicate the need for operative stabilization.
Operative Treatment Principles
Indications Operative management is the most definitive and effective method of management of scoliosis. It is appropriate for curves that exceed 50°.
Approaches Select the approach based on the curve characteristics and the experience of the surgeon.
Posterior fusion This standard approach allows correction and instrumentation of the majority of curves and levels.
Anterior fusion The advantages of anterior fusion include a reduction in the number of vertebra requiring fusion, less dissection, and correction of hypokyphosis. Anterior fixation provides excellent stability when extended to or just beyond the neutral vertebrae.
Fusion levels It is important to establish fusion levels thoughtfully. Too short a fusion may result in progression; fusion too long increases the risk of pain. Inappropriate fusion levels may cause spinal malalignment, changes in posture, and postfusion back pain. Definitions are useful in planning instrumentation and fusions.
Curves Fuse the major curve or largest curve, regardless of its flexibility, and minor or structural curves.
Instrument to reduce the scoliosis and maintain or improve sagittal alignment. Avoid excessive distraction, and incorporate solid fixation. Decorticate carefully, excise facet joints when feasible, and add supplemental bone. This supplemental bone may be autogenous, bank bone, or agents that induce osteogenesis.
Harrington instrumentation was the initial standard that incorporated distraction and compression of the ends of the curves. This technique provided little control of sagittal alignment and has been largely replaced.
Luque fixation utilizes sublaminar wires fixed to posterior rods.
Drummond fixation employs spinous processes to posterior rod fixation.
Cotrel and Dubousse introduced a universal system that provides translation and rotation in addition to distraction, which permits a solid three-dimensional correction. Many modifications of this form, such as the Isola and TRSH systems, have been developed.
Hybrid fixation utilizes options such as dual rods, laminar wires, pedicle screws, and cross links to achieve maximum stability.
Video-assisted thoracoscopy These procedures allow closed anterior releases, rib resection and harvesting, and insertion of correctional implants to reduce operative morbidity. Such procedures require special skills and instrumentation, and carry a steep learning curve. Due to the increased complication rate, the procedure is controversial.
Monitoring is utilized to reduce risk of neurological injury during spinal exposure and instrumentation.
Wake-up test Intraoperative wake-up neurological testing is effective and inexpensive but difficult to use, and has largely been replaced by continuous monitoring methods.
Intraoperative neurophysiological monitoring includes transcranial motor-evoked potentials and neurogenic motor-evoked potentials (NMEP).
Operative complications are not uncommon because of the magnitude of the procedure and also the vulnerability of the cord and nerve routes. These complications are described as early, such as neurological injuries, and late, such as pseudarthrosis.