Etiology and Epidemiology

Scoliosis is a complex, 3-dimensional deformity of the spine, with abnormalities in the coronal, sagittal, and axial planes. The diagnosis is based on a coronal plane curvature of >10 degrees using the Cobb method. Idiopathic scoliosis is a diagnosis of exclusion; other causes must be ruled out (see Table 671-1). The etiology of idiopathic scoliosis remains unknown and is likely multifactorial, involving both genetic and environmental components. Major theories have been based on genetic factors, metabolic dysfunction (melatonin deficiency, calmodulin), neurologic dysfunction (craniocervical, vestibular and oculovestibular), and biomechanical factors (asynchrony in spinal growth, anterior spinal overgrowth, and others). With regard to genetic factors, although several different modes of inheritance have been suggested (autosomal dominant, multifactorial, X-linked), a single locus has yet to be identified. Abnormalities identified in connective tissue, muscle, and bone appear to be secondary. Melatonin and calmodulin might have indirect effects, and subtle abnormalities in vestibular, ocular, and proprioceptive function suggest that abnormal equilibrium might also play a role.

Idiopathic scoliosis is classified according to the age at onset, including infantile (rare, birth to 3 yr), juvenile (3-10 yr), and adolescent (≥11 yr). Adolescent idiopathic scoliosis (AIS) is most common (∼70%). The prevalence of scoliosis (>10 degrees curvature) is ∼2-3%; however, approximately 0.3% have a curve >30 degrees. The incidence is roughly equal in girls and boys for small curves (<10 degrees), but girls have 10 times the risk of developing a curvature >30 degrees.

Clinical Manifestations

Patients usually present with a change in cosmetic appearance noted by family and/or friends or on a screening examination by a school nurse or primary care physician. The patient is evaluated in the standing position, from both the front and the side, to identify any asymmetry in the chest wall, trunk, and/or shoulders. Asymmetry of the posterior chest wall on forward bending (the Adams test) is the earliest abnormality (Fig. 671-1). Rotation of the vertebral bodies toward the convexity results in rotation and prominence of the attached ribs posteriorly. The anterior chest wall may be flattened on the concavity, due to inward rotation of the chest wall and ribs. Associated findings can include elevation of the shoulder, a lateral shift of the trunk, and an apparent leg-length discrepancy. The patient should also be evaluated from the side. The thoracic spine normally has a smooth, rounded kyphosis (20-50 degrees using the Cobb method from T3-T12) that extends down to the thoracolumbar junction, and the lumbar spine is normally lordotic (30-60 degrees using the Cobb method from T12-L5). Children normally have less cervical lordosis and more lumbar lordosis than do adults or adolescents. Typically, idiopathic scoliosis results in a loss of the normal thoracic kyphosis in the region of curvature (relative thoracic lordosis).

Figure 671-1 Structural changes in idiopathic scoliosis. A, As curvature increases, alterations in body configuration develop in both the primary and compensatory curve regions. B, Asymmetry of shoulder height, waistline, and elbow-to-flank distance are common findings. C, Vertebral rotation and associated posterior displacement of the ribs on the convex side of the curve are responsible for the characteristic deformity of the chest wall in scoliosis patients. D, In the school screening examination for scoliosis, the patient bends forward at the waist. Rib asymmetry of even a small degree is obvious

(From Scoles PV: Spinal deformity in childhood and adolescence. In Behrman RE, Vaughn VC III, editors: Nelson textbook of pediatrics, update 5, Philadelphia, 1989, WB Saunders.)

A careful neurologic examination should always be performed. A subset of curves are associated with an underlying neurologic diagnosis, especially in patients who present in the infant and juvenile years (20% have an associated intraspinal abnormality). The index of suspicion is raised in the presence of back pain or neurologic symptoms, café-au-lait spots, a sacral dimple or midline cutaneous abnormalities (hemangioma, hair patch or skin tag), unilateral foot deformity, or an atypical curve pattern. The examiner should always test the superficial abdominal reflex by lightly stroking the skin on both sides of the umbilicus. Normally, the umbilicus should deviate toward the side that was stroked. Asymmetry of the superficial abdominal reflex (or unilateral absence of this reflex) might suggest syringomyelia as an underlying diagnosis.

Screening for scoliosis facilitates earlier diagnosis and treatment, under the assumption that the natural history may be influenced by bracing, and that earlier identification of cases suitable for surgery reduces the complexity and risks of the surgery. Screening may be accomplished during primary care visits or as part of a school screening program. A consensus statement from professional societies (American Academy of Pediatrics, American Academy of Orthopaedic Surgeons, Pediatric Orthopaedic Society of North America, and the Scoliosis Research Society) states that if screening is to be carried out, this should be at 10 and 12 years of age for girls, and once at 13-14 years for boys. The Adams forward-bend test has been used to identify any asymmetry in the thoracic and/or lumbar region, and an inclinometer (scoliometer, Orthopaedic Systems Inc.) is also used to measure the degree of asymmetry. The number of degrees used for referral typically varies from 5 to 7, and the referral rate from these programs varies from 3% to 30%. School screening remains controversial, and less than half of the states in the USA have formal programs. The U.S. Preventive Services Task Force (USPSTF) has recently recommended against school screening in 2004, and further research is required to inform policy.

The natural history of idiopathic scoliosis varies considerably based on the age at diagnosis. Curvatures in excess of 80 degrees can result in restrictive pulmonary disease, and larger curves in excess of 100-120 degrees can result in a reduced life expectancy, due to cor pulmonale and cardiorespiratory failure. Scoliotic curves diagnosed in infancy through childhood are much more likely than adolescent curves to reach this magnitude. In general, adults with untreated AIS are expected to have similar life expectancy and similar functional activities, and no greater risk of cardiopulmonary complications, when compared with age-matched controls. Back pain may be more common, but it does not appear to be more disabling. Thoracolumbar or lumbar curves are more likely to cause pain during adulthood, particularly if there is an associated translational shift of the vertebrae. Dyspnea is common with thoracic curves of >80 degrees. Thoracic curves <30 degrees rarely progress after skeletal maturity, but those >45 or 50 degrees can continue to progress at approximately 1 degree per year through life. The cosmetic aspects of the deformity may be the most significant concern for the majority of patients with untreated AIS.

Radiographic Evaluation

Standing high-quality posteroanterior (PA) and lateral radiographs of the entire spine are recommended at the initial evaluation for patients with clinical findings that suggest a spinal deformity. On the PA radiograph, the degree of curvature is determined by the Cobb method, in which the angle between the superior and inferior end vertebra (tilted into the curve) is measured (Fig. 671-2). A line is drawn across the superior end plate of each end vertebra, and the angle between perpendicular lines erected from each of these is measured. Although the indications for performing MRI are variable, this modality is helpful when an underlying cause for the scoliosis is suspected based on age (infantile, juvenile curves), abnormal findings on the history and physical examination, and atypical radiographic features (curve patterns and/or specific features). Atypical radiographic findings include uncommon curve patterns such as the left thoracic curve, double thoracic curves, high thoracic curves, widening of the spinal canal, and erosive or dysplastic changes in the vertebral body or ribs. On the lateral radiograph, an increase in thoracic kyphosis or an absence of segmental lordosis might suggest the presence of an underlying diagnosis.

Figure 671-2 A-C, Cobb angles measurements.

(From Morrissy, RT, Weinstein, SL: Lovell & Winter’s pediatric orthopaedics, ed 6, Philadelphia, 2006, Lippincott Williams & Wilkins.)

Treatment

Options for treatment include observation, bracing, and surgical treatment. Treatment decisions are based on the natural history of each curvature, which relates to age (degree of skeletal maturity or growth remaining), the magnitude of the curve, and occasionally associated diagnoses and/or medical considerations. A positive family history does not help predict the behavior of an individual curve. Observation is always indicated for curvatures <20 degrees. Curves of larger magnitude may be treated by bracing or surgery. The risk of curve progression depends on the amount of growth remaining, the curve’s magnitude, and gender. More than one parameter must be used when determining the amount of growth remaining, and both clinical (age, annual growth velocity, menarchal status, Tanner stage) and radiographic (Risser sign, skeletal age, maturation of olecranon apophysis) measures are available. Curves are more likely to progress if there is significant growth remaining (premenarchal, Tanner stage I or II, Risser 0 or 1). Premenarchal girls with curves between 20 and 30 degrees have a significantly higher risk of progression than do girls 2 yr after menarche with similar curves. Boys with curvature of the same magnitude appear to have similar risks of progression when judged by other maturation standards; however, the assessment of skeletal maturity in boys is more difficult.

Bracing

The goal of bracing is to prevent progression of the deformity, thereby reducing the need for surgery. The efficacy of bracing in AIS remains controversial, but most centers in North America offer a brace to selected patients with progressive curvatures. In AIS, the typical indications for bracing are a curve >30 degrees, or a curve from 20-25 degrees that has progressed >5 degrees, in a skeletally immature patient (Risser 0,1, or 2). Bracing is thought to be ineffective in curves >45 degrees. An “in brace” correction of 50% in Cobb angle is desirable.

The success of bracing is thought to increase with greater time spent in the brace, and the ideal program includes 23 hours in the brace per day. Protocols vary between 16 and 23 hours per day, recognizing that full compliance is difficult to achieve in the adolescent population. Bracing is commonly used as a temporizing measure for infantile and juvenile scoliosis given the high likelihood of significant progression, and the need to delay more definitive treatment. The success rate is much lower for infantile and juvenile curvatures, but the goal is to delay progression.

There are several options for braces (Fig. 671-3). The Milwaukee brace, employing longitudinal traction from the skull to the pelvis with lateral compression of the chest wall, can be adjusted for growth and thus is a good brace for patients with infantile or juvenile scoliosis. Underarm braces (the Boston or Wilmington braces) are less obvious and so are often preferred by adolescents. The Charleston brace provides a corrective force and is used only at night.

Figure 671-3 Various brace types.

(From Morrissy, RT, Weinstein, SL: Lovell & Winter’s pediatric orthopaedics, ed 6, Philadelphia, 2006, Lippincott Williams & Wilkins.)

Surgery

Surgical treatment is indicated for the majority of patients with infantile or juvenile idiopathic scoliosis and in selected patients with AIS, when other methods of treatment have failed to control the deformity, and when further progression would be expected to result in unacceptable cosmesis and/or physiologic abnormalities. Such deformities are typically treated by a definitive spinal arthrodesis (fusion). The majority of progressive infantile and juvenile curves ultimately require a spinal arthrodesis, and the goal is to delay the definitive procedure until the pulmonary system and thoracic cage have matured and the trunk height has been maximized.

An alternative strategy is required for curvatures that progress despite bracing. In some centers, serial casting under general anesthesia is employed for selected infantile and juvenile curves to gain correction into a “braceable” range, followed by application of a spinal orthosis. The other option for progressive curvatures is a “growing rod” construct. A spinal rod (or 2 rods) is attached to anchors at the top and at the bottom of the curvature, and distraction forces are applied to achieve correction. The rods hold the spine in the corrected position, and they must then be lengthened every 6 months to maintain correction. Many curves have been controlled for years using such a protocol, and definitive fusion is delayed until a more optimal age.

With regard to AIS, surgical treatment is usually indicated for skeletally immature patients with progressive thoracic curves >45 degrees and skeletally mature patients with thoracic curves >50-55 degrees. Lumbar curves are more likely to progress, and surgical stabilization may be offered for curves as low as 35-40 degrees if there is a significant shift of the trunk relative to the pelvis and lower extremities. The goals of surgery are to arrest progression of the deformity, to improve cosmesis, and to minimize the number of vertebral segments that are stabilized. These are achieved through a spinal fusion or arthrodesis, and implants are used to apply mechanical forces to the bony elements to affect correction and to hold the spine in the corrected position until the spine fuses. Postoperative immobilization is usually not required. Options for bone grafting include autograft (iliac crest) or allograft, and in recent years most surgeons have used cancellous allograft with or without enhancers such as demineralized bone matrix.

The most common procedure is an instrumented posterior spinal fusion, and the typical spinal implant construct includes 2 rods anchored to the spine by hooks, wires, and/or screws (Fig. 671-4). In the last few years there has been significant interest in using a construct with pedicle screws at each level. Although correction of the axial deformity (rotation of the rib cage) is more pronounced with this technology, it remains unclear whether patient outcomes are improved. An anterior release and fusion, performed through a thoracotomy or thoracolumbar exposure, is indicated for isolated thoracolumbar and lumbar curves, to improve correctability of stiffer curves, and to prevent curve progression (“crankshaft”) from continued anterior growth of the spine in selected patients with considerable growth remaining. A construct with multiple pedicle screws can allow the surgeon to avoid an anterior approach in many larger or stiffer curves (more powerful correction) and in younger patients (stiff enough to resist anterior spinal growth and prevent crankshaft). Thoracoscopic surgery has also been used to perform an anterior release with or without instrumentation and fusion, but this technique has been used much less often since the advent of thoracic pedicle screws. For idiopathic thoracolumbar and lumbar curves, an anterior fusion with instrumentation (usually screws in the vertebral body connected to 1 or 2 rods) can be done as an alternative to save lumbar motion segments.

Figure 671-4 A, Preoperative standing posteroanterior radiograph of a 14 yr old girl who was skeletally immature and developed a 68-degree right thoracic and a 53-degree left lumbar scoliosis. Her trunk was shifted to the right, and the left shoulder was slightly depressed. B, Based on the risk of future progression, she was treated by an instrumented posterior spinal fusion from T3 to L3, with correction of the right thoracic curve to 20 degrees and the left lumbar curve to 10 degrees. Coronal spinal balance was restored, and shoulder height was maintained.

There has been an interest in developing techniques to tether spinal growth, most commonly by placing metallic staples across each disk space on the convexity of a curvature. The goal is to slow or arrest growth on the convexity while allowing growth to proceed on the concavity, thereby preventing progression and possibly resulting in permanent correction without the need for an arthrodesis. The indications for this technique, and the long-term results, remain to be determined.

Neuromuscular Scoliosis

Scoliosis is often identified in children with neuromuscular diseases such as cerebral palsy, the muscular dystrophies and other myopathies, spinal muscular atrophy, Friedreich ataxia, myelomeningocele, polio, and arthrogryposis. The etiology and natural history differ from those seen in idiopathic and congenital scoliosis. Most cases result from weakness and/or imbalance of the trunk musculature, and spasticity plays a role in many patients as well. Coexisting congenital vertebral anomalies are seen in patients with myelomeningocele. Neuromuscular scoliosis is most common in the nonambulatory population and is diagnosed in up to 68% of nonambulatory patients with cerebral palsy and >90% of patients with Duchenne muscular dystrophy. The most common pattern is a long, C-shaped curve, which is often associated with pelvic obliquity. In general, the clinical course depends on the severity of neuromuscular involvement and the nature of the underlying disease process (especially if it is progressive).

The consequences of a progressive scoliosis in the neuromuscular population involve both function (sitting and standing balance) and ease of care; in some cases, visceral function is compromised. In patients who are wheelchair bound, one arm may be required for trunk support, which impairs upper extremity function. An associated pelvic obliquity results in asymmetric seating pressures, which can limit sitting endurance and possibly result in ischial decubiti. Severe curves may be associated with decreased pulmonary reserve, especially when the apex is in the thoracic spine, compounding pre-existing respiratory problems. Pain may be experienced from impingement of the rib cage on the iliac crest in large thoracolumbar curves. Marginal ambulators can lose the ability to ambulate as a result of scoliosis.

Syndromes and Genetic Disorders

Syndromes and genetic diagnosis constitute a diverse group of diagnoses; representative examples include neurofibromatosis, osteogenesis imperfecta, connective tissue diseases (Marfan syndrome, Ehlers-Danlos syndrome), and Prader-Willi syndrome. Patients with these diagnoses should have their spine examined routinely during visits to their primary care physician. As for other types of scoliosis, the follow-up and treatment is based on the age of the patient, the degree of deformity, whether progression has been documented, and the underlying diagnosis.

Compensatory Scoliosis

Leg-length inequality is common and is usually associated with a small compensatory lumbar curvature (Chapter 668). This is 1 cause of false-positive screening examinations. Pelvic tilt toward the short side is associated with a lumbar curve (convexity away from the short leg). There is little evidence to suggest that a small compensatory lumbar curve places the patient at risk of progression or back pain. Because children with leg-length inequality can also have idiopathic or congenital scoliosis, a standing radiograph may be obtained with a block under the foot on the short side (to correct the leg-length discrepancy) to level the pelvis. If the curvature disappears when the limb-length discrepancy is corrected, then a diagnosis of a compensatory curve is made. An alternative is a PA radiograph with the patient seated. In neuromuscular disorders such as polio or cerebral palsy, an adduction or abduction contracture of the hip (fixed infrapelvic contracture) may be compensated for by a lumbar scoliosis to maintain standing or sitting balance. For patients who ambulate, a 10-degree fixed contracture will result in up to 3-cm apparent leg-length discrepancy.

Flexible Kyphosis (Postural Kyphosis)

Patients with postural kyphosis usually present with cosmetic concerns, and the deformity can be corrected voluntarily. There are no abnormalities of the vertebrae noted on the standing lateral radiograph. Postural kyphosis does not progress to a structural deformity, nor is there evidence to suggest that patients will have problems later in life. Any coexisting back pain is typically mild, is activity related, and occurs in the midthoracic region by the apex of the curvature. In addition to reassurance, activity modifications are used to treat any discomfort, and strengthening the extensor muscles of the spine is potentially beneficial as well. Neither bracing nor surgery plays a role in the management of this condition.

Structural Kyphosis

Radiographic Evaluation

Standing PA and lateral radiographs are obtained (Fig. 671-7). The recommended technique for the lateral radiograph involves folding the arms across the chest. A vertical plumb line dropped from C7 should intersect the anterosuperior corner of the sacrum for maintenance of sagittal spinal balance. A coexisting spondylolisthesis is rarely identified on the lateral radiograph. The standing PA radiograph often reveals a mild scoliosis, which is rarely progressive. An MRI is indicated in the presence of neurologic symptoms, and some surgeons routinely obtain an MRI before correcting a kyphosis.

Figure 671-7 Standing lateral radiograph of a 14 yr old boy with severe Scheuermann kyphosis. This measures 92 degrees between T3 and T12. Note the wedging of the vertebrae at T6, T7, T8, and T9. The normal thoracic kyphosis is ≤40 degrees.

Congenital Kyphosis

Congenital kyphosis can result from either a failure of formation (more progressive and dangerous) or a failure of segmentation. In an anterior failure of formation (type I), there is an absence of a significant portion of the vertebra, resulting in a progressive kyphotic deformity or toppling over of the spine. This deformity results in neurologic dysfunction, if untreated, from compression of the spinal cord at the apex of the deformity. In type II congenital kyphosis there is an anterior failure of segmentation, with fusion of the involved vertebrae. Progression of kyphosis results from growth of the posterior elements of the spine and is typically slower and more variable than in type I deformities. There is a much lower chance of neurologic dysfunction. Patients must be followed closely, and treatment is required in a significant number of cases. As for congenital scoliosis, abnormalities of other organ systems (cardiac, renal, spinal cord) must be ruled out.

The treatment depends on the type of malformation, the degree of deformity, and whether neurologic symptoms are present. Bracing is ineffective for the primary curvature, but it is occasionally required to control compensatory curves. Surgery is the only effective treatment option for progressive curves or those with a poor natural history (type I), and it typically involves a spinal arthrodesis. Ideally, this can be performed before a significant deformity develops. Because the natural history is so poor for type I kyphoses, spinal fusion is usually performed shortly after the diagnosis is made. Depending on the degree of deformity and/or presence of neurologic dysfunction, excision of the vertebral remnant may be required to decompress the spinal cord and to restore alignment, in addition to a posterior spinal fusion. The vertebral remnant may be excised using an anterior approach before the posterior surgery or through the same posterior approach used for the spinal fusion. Surgical fusion can arrest progression, but deformity correction may be required to achieve a balanced spine. In patients with a mild deformity treated by a posterior spinal fusion, continued growth of the anterior column of the spine can result in some further improvement of the curvature over time. There is a significant risk of neurologic complications associated with surgery for congenital kyphosis, particularly the type I deformities.

Clinical Evaluation

The history begins with the location, character, and duration of symptoms. Pain that is constant, unrelieved by rest, and wakes the patient from sleep is more likely to be secondary to an infection or neoplasm, as are systemic signs (fever) or symptoms (chills, weight loss, malaise). Symptoms of neurologic dysfunction also suggest that an underlying diagnosis is likely. The history must also uncover the presence of any radicular symptoms, gait disturbance, muscle weakness, alterations in sensation, and changes in bowel and/or bladder function.

The physical examination includes a complete musculoskeletal and neurologic assessment, and an abdominal exam should be performed. In appropriate cases, a gynecologic examination may also be helpful. The musculoskeletal examination begins in the standing position, noting any changes in alignment in the frontal or sagittal plane. Range of motion should be assessed in flexion, extension, and lateral bending. Flexion increases compression across the anterior elements of the spine (vertebral bodies and disks), and extension results in compression across the posterior elements (facet joints, pars interarticularis). Pain with flexion suggests an abnormality in the vertebral body or disk. Younger children should be asked to pick up an object off the floor, and pain is often due to diskitis. Pain with hyperextension (ask patient to hold the hyperextended position for 10-20 seconds) might have spondylolysis. Palpation will reveal any areas of tenderness and/or muscle spasm. Leg lengths are also assessed, by palpating the top of the iliac wings while the patient is standing. Because spinal pain may be referred, an abdominal examination should be performed, and in girls, a gynecologic evaluation may be necessary. The sacroiliac joint should be stressed by compression across the iliac wings or by forced external rotation with the hip and knee flexed to 90 degrees. The hamstring muscles should always be evaluated, because contracture is commonly associated with diagnoses such as Scheurmann disease, spondylolysis or spondylolisthesis, a herniated disk (or slipped vertebral apophysis), or other pathologies.

The neurologic examination includes manual muscle testing and an evaluation of sensation and proprioception. The superficial abdominal reflex should be tested by gently stroking the skin on each of the 4 quadrants surrounding the umbilicus. Normally, the umbilicus moves toward the area stimulated, and a normal examination is defined by a symmetric response (present or absent on both sides). Asymmetry suggests the presence of a subtle abnormality of spinal cord function, most commonly syringomyelia. The straight leg raise test is performed by raising up one leg with the knee extended. This test evaluates tension on the lower spinal nerve roots, and radicular symptoms (pain or tingling below the knee) will be reproduced. Possible causes of radiculopathy include a herniated disk, slipped vertebral apophysis, spondylolisthesis, tethered cord, and other causes. To further confirm the abnormal compression or stretch on the nerve root, the limb may be lowered to a position in which the symptoms are no longer present, and the foot is then dorsiflexed. Reproduction of the findings or symptoms with dorsiflexion of the foot further suggests the presence of nerve root compression or tension.

Radiographic and Laboratory Evaluation

There are no specific guidelines for imaging in evaluating back pain in childhood and adolescence. For patients with any concerning signs or symptoms or for those with persistent symptoms, the initial study is commonly posteroanterior and lateral radiographs of the involved region of the spine. With lumbar back pain, some clinicians also obtain right and left oblique views. In patients with a normal neurologic examination, a bone scan can help to identify the location of pathology, and a bone scan with single-photon emission CT (SPECT) is more specific for the diagnosis of a stress reaction or spondylolysis, although an established stress fracture can have a negative scan. MRI is most helpful when neurologic symptoms or findings are present. CT is best at defining bony lesions, and a CT scan with thin cuts may be useful in the evaluation of spondylolysis.

Laboratory studies should also be considered, especially when systemic signs or constitutional symptoms are present, and may include a complete blood cell count with differential, erythrocyte sedimentation rate, C-reactive protein, and occasionally a rheumatoid factor, antinuclear antibody, Lyme, and/or HLA-B27.

Clinical Manifestations

Symptomatic patients with spondylolysis or spondylolisthesis usually present with mechanical low back pain that can radiate to the buttocks and thigh but rarely below the knee. The pain is exacerbated by spinal hyperextension, which exerts compression on the posterior elements. A useful provocative test, with the patient standing, involves placing the spine in hyperextension and holding the position for up to 10-20 seconds. This compresses the posterior elements and might reproduce the symptoms. In contrast, pain emanating from disk space pathology is exacerbated by spinal flexion. Physical examination might also reveal tenderness over the spinous process of the involved vertebra. Hamstring spasm, with or without contracture, is commonly observed.

The physical findings may be more pronounced in patients with spondylolisthesis. The buttocks appear flattened (sacrum is more vertically inclined, lumbosacral kyphosis), and the abdomen might appear more protuberant (hyperlordosis above the lumbosacral kyphosis). There is often a palpable step off between the spinous processes at the involved levels, especially with a high-grade slip. Hamstring spasm or contracture is usually more pronounced than in spondylolysis. Gait disturbance is also observed, typically characterized by mild crouching, a short stride length, and an incomplete swing phase. A careful neurologic examination is required. In addition to back pain, neurologic symptoms (radiculopathy or bowel or bladder dysfunction) can result from compression of the cauda equina or nerve roots. Radicular symptoms or findings are uncommon except in high-grade spondylolisthesis, when there may be excessive tension (or mechanical compression) on the lower lumbar nerve roots. In contrast to lumbar disk herniations, which most commonly affect the lower root (L4-L5 disk herniation compresses the L5 nerve root), spondylolisthesis of L5 on S1 affects the L5 nerve root.

Radiographic Evaluation

The initial evaluation of the lumbar region should include high-quality anteroposterior, lateral, and oblique radiographs. The pars is best visualized on the oblique radiographs, and a pars defect has been termed the Scotty dog sign. Standing PA and lateral radiographs are obtained if findings suggestive of scoliosis or hyperkyphosis are also present (Figs. 671-8 and 671-9). In patients with normal plain films, a bone scan with SPECT images can help to diagnose a spondylolysis during the early stages (stress reaction), before a fracture or an established pseudarthrosis develops. A CT scan with thin cuts can establish the presence of a pars defect or a pseudarthrosis. If the bone scan shows no increased uptake in the region, and a CT scan demonstrates a pars defect, then the potential for healing is felt to be limited. Although MRI is most commonly indicated in the presence of signs or symptoms of cauda equina or nerve root involvement, it has been used more and more during the diagnostic phase.

Figure 671-8 A, Normal spine at 9 mo of age. B, Spondylolysis in the L4 vertebra at 10 yr of age.

(From Silverman FN, Kuhn JP: Essentials of Caffrey’s pediatric x-ray diagnosis, Chicago, 1990, Year Book Medical Publishers, p 94.)

Figure 671-9 Defect in the pars interarticularis (arrow) of the neural arch of L5 (spondylolysis) that has permitted the body of L5 to slip forward (spondylolisthesis) on the body of S1.

(From Silverman FN, Kuhn JP: Essentials of Caffrey’s pediatric x-ray diagnosis, Chicago, 1990, Year Book Medical Publishers, p 95.)

Spondylolisthesis is graded according to the degree of translation of the superior vertebra as follows: grade 1, <25%; grade 2, 25-50%; grade 3, 50-75%; grade 4, 75-100%; and grade 5, complete displacement or spondyloptosis. The degree of rotation of the upper vertebra on the lower (kyphosis) is also measured as the angle in between a line drawn along the posterior margin of the sacrum and a line drawn along the superior end plate of the L5 vertebra (slip angle). In patients with spondylolisthesis, flexion and extension films are occasionally performed to identify instability (excessive translation through this range of motion). Because progressive slippage can occur in a subset of skeletally immature patients, a standing lateral radiograph of the lumbar spine should be considered every 6-12 mo.

Treatment

Asymptomatic patients with spondylolysis require no active treatment, but those with pain are treated with rest and/or modification of activity, physical therapy (focusing on hamstring stretching and strengthening of the abdominal musculature), and non-narcotic analgesics. In patients with a stress reaction or early stress fracture without an established pseudarthrosis, healing may be achieved with nonoperative measures. Unilateral defects are more likely to heal when compared with bilateral defects, and the presence of high signal in the adjacent pedicle on MRI also implies a better chance of healing. A modified lumbosacral orthosis, which reduces lumbar lordosis (15 degrees of flexion of the lumbar spine) and immobilizes the spine, is typically recommended for 3-4 mo full time. For patients with an established pseudarthrosis, the goal is relief of symptoms rather than union. Overall, nonoperative measures are successful in the majority of patients, and a successful clinical outcome does not depend on healing of the lesion.

Surgery is offered when symptoms persist despite an adequate trial of nonoperative therapy. For spondylolysis, surgical options include repair of the pars defect versus spinal fusion. If the spondylolysis is at L5, then a posterior spinal fusion from L5 to S1 is most commonly performed. For the uncommon cases in which the defect is at L4 or at higher levels, techniques for repairing the defect should be considered. If successful, these procedures will avoid the need for surgical fusion. Some surgeons use an MRI to evaluate the disk space at that level and select a fusion rather than a pars repair if there are degenerative changes in the disk.

Recommendations for managing spondylolisthesis depend on the age of the patient, the presence of symptoms (pain and/or neurologic), the degree of deformity, and to a lesser extent cosmetic concerns. For low-grade lesions (<50% slippage) with chronic symptoms despite nonoperative treatment, a posterior spinal fusion alone, with or without instrumentation, may be successful. For skeletally immature patients with >50% slippage, with or without symptoms, surgery is offered given the risk of progression. The surgical approach for higher-grade slips varies among surgeons and institutions. The main principle is to stabilize the unstable segment of the spine through spinal fusion, either a posterior or an anterior and posterior spinal fusion with spinal instrumentation.

Whether or not to reduce the spondylolisthesis at the time of surgery remains a subject of controversy. A reduction may be achieved through gravity or intraoperative positioning or through direct realignment using the spinal implants. Although neurologic symptoms can resolve with stabilization, a decompression of the neural elements is commonly performed as a component of the stabilization procedure for high-grade spondylolisthesis.

Clinical Manifestations

A high index of suspicion is required to establish the diagnosis of diskitis, especially in younger patients. The differential includes vertebral osteomyelitis (see Table 671-3). In addition to back pain and/or fever, patients can experience malaise, and toddlers can develop a limp or refuse to walk or sit. Spinal motion is voluntarily reduced to alleviate pain, and paraspinal muscle spasm is common. Flexion of the spine compresses the anterior elements of the spine and should increase any discomfort. This may be tested by asking the child to pick up an object from the ground. There may a loss of the normal lumbar lordosis. Neurologic manifestations are rare. Patients may be afebrile, and although a complete blood count might remain normal, the erythrocyte sedimentation rate and the C-reactive protein are usually elevated. Older children might have fever and abdominal pain.

Radiographic Evaluation

A PA and lateral radiograph of the thoracolumbar spine is the first imaging study ordered when the diagnosis is suspected, recognizing that characteristic findings of disk space narrowing and irregularity of the adjacent vertebral end plates often take 2-3 wk to develop after the onset of symptoms. Other changes noted on plain radiographs include demineralization, with erosions at the vertebral margins, and loss of vertebral height. The diagnosis may be established earlier using either a technetium bone scan or MRI. MRI provides more information and is most helpful in identifying abscesses and ruling out vertebral osteomyelitis. Plain radiographs during the course of follow-up might reveal sclerosis at the margins of the adjacent vertebral bodies after several months (remineralization), and although some restoration of vertebral body height can occur, disk space narrowing usually persists, and in some cases the adjacent vertebrae can become fused or enlarged.

Treatment

Once the diagnosis is established, treatment involves both treating symptoms and giving antibiotics. Activity restriction, analgesics, and immobilization in a spinal orthosis all help to relieve symptoms. Typically, a thoracolumbosacral orthosis is worn for 4-6 wk. Antibiotics effective against S. aureus are prescribed for 4-6 wk, and although treatment protocols vary, an intravenous route of administration is typically used for at least 1-2 wk. The treatment can then be converted to an oral regimen, assuming that the clinical response has been adequate in terms of both symptoms and inflammatory markers. A CT-guided needle biopsy of the disk space is reserved for children who fail to respond to these treatment measures and those in whom an alternative diagnosis is suspected. Surgical treatment is rarely required and involves either an open biopsy or drainage of an abscess.

Clinical Manifestations

Symptoms of intervertebral disk herniation in adolescents are similar to those in adults; the major complaint is back pain, and radicular symptoms (if present) generally appear later in the course. The back pain is often made worse by coughing or straining. Although a history of acute injury is found in a subset of cases, many patients have a history of repetitive stresses, such as young elite athletes. Some patients have congenital anomalies of the lumbosacral spine. On physical examination, both paraspinal muscle spasm and a decrease in range of motion are common. Overt signs of neurologic involvement are absent in most patients, but the straight leg raise test is usually positive. With the positive straight leg test, the neurologic findings often do not correlate with the level of disk herniation. An intraspinal tumor should always be included in the differential diagnosis.

Radiographic Evaluation

Radiographs often show loss of lumbar lordosis and a lumbar curvature (not a true scoliosis) that is due to muscle spasm. Degenerative changes and/or a loss of intervertebral disk height is occasionally noted on plain films; however, apophyseal fragments are usually not seen. MRI is the best study to establish the diagnosis, and CT is especially helpful to visualize a partially ossified fragment associated with a slipped apophysis. Types of slipped vertebral apophysis include an avulsion of the cortical margin with or without a fragment of cancellous bone, a lateral fracture, and a posterior wall fracture that extends from the superior vertebral endplate to the inferior vertebral endplate.

Treatment

The initial treatment is nonoperative in most patients and focuses on rest, activity modification, analgesics, and physical therapy. An orthosis can provide additional symptomatic relief. Complete bed rest is not recommended. The role of epidural steroids remains to be determined. Surgical treatment should be considered when nonoperative measures have failed or when a profound neurologic deficit or cauda equina syndrome is present either initially or as the clinical course evolves.

Unfortunately, children and adolescents respond less favorably to nonoperative therapy compared with adults, and a significant percentage require surgical intervention. The surgical technique involves laminotomy and subtotal disk excision to decompress the neural elements. In the case of a slipped vertebral apophysis, a similar approach is employed for decompression of the neural elements, but there is some controversy about whether or not to routinely remove the apophyseal fragment. Some surgeons remove the fragment when there are neurologic symptoms; one report suggested that an intraoperative assessment of the mobility of apophyseal fragments is helpful, and the authors only removed loose fragments. A bilateral laminotomy may be required in these cases to address the pathology.

Although the initial results are excellent in the majority of patients, the literature suggests that up to a third of patients have recurrent symptoms of back or leg pain at longer term follow-up. The reoperation rate is in the range of 15%, similar to that of the adult population. A spinal fusion may be required when clinical instability is present.