AAOS Comprehensive Orthopaedic Review
Section 3 - Pediatrics
Chapter 27. Pediatric Spine Conditions
I. Idiopathic Scoliosis (Infantile/Juvenile/Adolescent)
A. Overview (epidemiology)
1. Definition of idiopathic scoliosis (IS)—A coronal plane deformity of >10° (by Cobb method) with no known cause.
2. Normal thoracic kyphosis is 20° to 45°; normal lumbar lordosis is 30° to 60°.
3. Genetics—Autosomal dominant with variable penetrance.
1. Scoliometer measurement >5°
a. 2% to 5% false-negative rate for curve >20°
b. 50% false-positive rate for curve <20°
2. Infantile IS can dramatically impair alveolar growth and thoracic cage development, causing significant cardiopulmonary impairment with restrictive lung disease and possibly cor pulmonale.
a. Growth velocity of the T1-L5 segment is fastest in the first 5 years of life, with the height of the thoracic spine doubling between birth and skeletal maturity.
b. Male to female ratio is 1:1.
c. The most common curve location is the thoracic spine; 75% of curves are left convex.
d. Risk of progression overall is 10%. Curves with apical rib-vertebra angle difference (RVAD), or Mehta angle, >20° (
Figure 1) and phase 2 apical rib-vertebrae relationship (overlap of the rib head with the apical vertebral body) (
Figure 2) are at the greatest risk of progression.
*Scott J. Luhmann, MD, is a consultant or employee of Stryker and Medtronic. David L. Skaggs, MD, or the department with which he is affiliated has received research or institutional support and miscellaneous nonincome support, commercially derived honoraria, or other non-research-related funding from Medtronic and Stryker Spine, and is a consultant or employee for Medtronic and Stryker Spine.
[Figure 1. To measure the rib-vertebra angle difference (RVAD), a line is drawn perpendicular to the end plate of the apical vertebrae (a). Next, a line is drawn from the midpoint of the neck of the rib through the midpoint of the head of the rib to the perpendicular on the convex side (b). The resultant angle is calculated. The angle on the concave side is calculated in a similar manner. Concave - convex = RVAD.]
e. 22% of patients with curves ≥20° have neural axis abnormality; approximately 80% of these patients will require neurosurgical care.
3. Juvenile IS
a. Incidence is higher in females than in males.
b. Right thoracic curves are most common.
c. Spontaneous resolution is uncommon.
d. Curves with RVAD >20° and phase 2 rib-vertebrae relationship are at increased risk of progression.
e. 95% of curves will progress.
f. Incidence of neural axis abnormalities is 20% to 25%; hence MRI is necessary.
4. Adolescent IS
a. Polygenetic interaction is suspected.
b. Female to male ratio is 1:1 for small curves but increases to 10:1 for curves >30°.
c. Risk of progression is related to curve size and
[Figure 2. Rib-vertebra relationships. A, Phase 1 rib-vertebra relationship demonstrating no overlap of the rib head and vertebral body. B, Phase 2 rib-vertebrae relationship. The overlap of the rib head on the vertebral body is indicative of curve progression.]
remaining skeletal growth, which is assessed by Tanner stage, Risser grade, age of menarche, and presence of open triradiate cartilages.
i. Girls at greatest risk for progression are premenarchal, Risser grade 0, Tanner stage <3, and have open triradiate cartilage.
ii. Peak height velocity (fastest growth) generally occurs before Risser grade 1.
iii. Peak height velocity in adolescence is approximately 10 cm/year and occurs just before the onset of menses in girls.
iv. If the curve is >30° at peak height velocity, the curve is likely to require surgery.
5. Long-term implications of scoliosis are dependent on the size of the curve at skeletal maturity.
a. Thoracic curves >50° and lumbar curves >40° have been shown to progress up to a mean of 1°/year after skeletal maturity.
b. Curves >60° can have a negative impact on pulmonary function tests, but symptomatic cardiopulmonary impact traditionally is seen with curves >90°.
c. With significant curves, a mild increase in the incidence of back pain is likely in adulthood.
1. Physical examination
a. The physical examination should include a detailed neurologic examination of the lower extremities (sensory examination, motor examination, and reflexes).
b. Skin evaluation should include inspection for cafe-au-lait spots (neurofibromatosis).
c. Lower extremity evaluation should rule out cavovarus feet (associated with neural axis abnormalities) and document normal strength, gait, and coordination.
d. Hairy patches, dimples, nevi, or tumors over the spine may be indicative of spinal dysraphism.
e. Dimples outside the gluteal fold are generally benign.
f. Asymmetric abdominal reflexes are associated with a syrinx and are an indication for MRI of the spine.
2. Radiographic evaluation
a. PA and lateral upright (weight-bearing) views (36-inch cassette) should be obtained.
b. Bending or traction films are useful for surgical planning.
3. MRI of spine
a. MRI is used to rule out intraspinal anomalies (tethered cord, syringomyelia, dysraphism, and spinal cord tumor).
i. Atypical curve patterns (eg, left thoracic curve, short angular curves, absence of apical thoracic lordosis, absence of rotation and congenital scoliosis)
ii. Patients <10 years of age with a curve >20°
iii. Abnormal neurologic finding on examination, abnormal pain, rapid progression of curve (>1°/mo)
c. Intraspinal anomalies are referred to a neurosurgeon for evaluation.
d. A syrinx (
Figure 3) is commonly associated with scoliosis without rotation and an asymmetric umbilicus reflex.
Infantile (<3 years of age) represents 4% of IS cases.
[Figure 3. Large syrinx involving the entire spine of a 2-year-old boy. A, Sagittal T1-weighted MRI scan shows the syrinx to be largest at the level of the lower thoracic spine (arrows). B, Axial T1-weighted image confirms that the syrinx is located within the center of the spinal cord.]
Table 1. Lenke Classification of Idiopathic Scoliosis*]
Juvenile (3 to 10 years of age) represents 15% of IS cases.
Adolescent (>10 years of age) represents 80% of IS cases. Prevalence: 2% to 3% for curves 10° to 20°, 0.3% for curves >30°.
2. Curve location
a. Cervical (C2 through C6)
b. Cervicothoracic (C7-T1)
c. Thoracic (T2-T11/12 disk)
d. Thoracolumbar (T12-L1)
e. Lumbar (L1-2 disk through L4)
3. Surgical classification of adolescent idiopathic scoliosis
b. Lenke classification (Table 1) describes six major curve types with modifiers for the lumbar curve and amount of thoracic kyphosis (T5 through T12).
E. Treatment—Recommendations are based on the natural history of scoliosis.
a. Infantile: Patients with RVAD >20°, phase 2 rib-vertebrae relationship, and Cobb angle >30° are at high risk of progression (Figures 1 and 2). Bracing may be considered when the Cobb angle is >20°, but many curves of this size improve spontaneously, so it is reasonable not to brace until a curve reaches 30°.
i. Bracing is usually started for juveniles with curves >20° and adolescents >25°; smaller curves are treated with observation.
ii. Bracing is used for skeletally immature patients (Risser 0, 1, or 2). Recommended for 16 to 23 h/day and continued until completion of skeletal growth or curve progression to >45° (at which point bracing is no longer considered effective).
iii. The aim of bracing is to halt progression of curve during growth, not to correct scoliosis.
iv. Thoracic hypokyphosis is relative contraindication for bracing.
v. An underarm brace, or thoracolumbosacral orthosis (TLSO), is most effective when the curve apex is at T7 or below.
vi. The efficacy of brace treatment is controversial.
i. Infantile/juvenile—Cobb >50° to 60°.
ii. Adolescent—Thoracic curves >45° to 50°. Lumbar curves >45° or marked trunk imbalance with curve >40° (relative).
i. Patients with active infections
ii. Poor skin at surgical site
iii. Inability to adhere to postoperative activity limitation
iv. Significant concomitant medical comorbidities
i. Infantile/juvenile—Dual growing rod constructs can permit growth of affected spine up to 5.0 cm over the instrumented levels.
ii. Adolescent—Both anterior and posterior fusions have been reported to be effective in correcting and maintaining correction during the postoperative period. Anterior release has been performed in addition to posterior fusion for large (>70° to 80°), stiff (<50% flexibility index) curves but may not be necessary with newer generation spinal implants. For large, rigid curves, Smith-Petersen osteotomies (Ponte), pedicle subtraction osteotomies, and vertebral column resections can help improve correction and spinal balance. In Risser 0 patients with open triradiate cartilage and Risser 0, anterior diskectomy and fusion has been recommended to avoid the crankshaft phenomenon, although the use of thoracic pedicle screws in this population may obviate the need for anterior fusion.
1. Crankshaft phenomenon
a. Progression of spine deformity after a solid posterior fusion due to continued anterior spinal growth
b. Can be avoided by concomitant anterior spine fusion at the time of posterior fusion
2. Short-term postoperative complications include ileus, syndrome of inappropriate antidiuretic hormone release, atelectasis, pneumonia, and superior mesentertic artery syndrome.
3. Infections occur in up to 5% of patients.
a. Early infection (<6 months after surgery) is treated with irrigation and debridement and antibiotics without removal of implants because fusion is assumed to not have occurred.
b. Chronic deep infections of spinal implants are treated with implant removal and intravenous antibiotics, although progression of deformity over time may occur.
4. Implant failure and pseudarthrosis occur in up to 3% of patients, but this is uncommon in the skeletally immature.
5. Neurologic injury occurs in up to 0.7% of patients as a result of compressive, tensile, or vascular phenomenon. Current recommendations are for intra-operative spinal cord monitoring of somatosensory-evoked potentials (SSEPs) and neurogenic motor-evoked potentials (MEPs).
6. Decreased pulmonary function has been reported following anterior fusion and posterior thoracoplasty.
a. Thoracoscopic approaches to the thoracic spine have less negative impact on pulmonary function than open thoracotomy.
b. Similarly, open anterior thoracolumbar fusion has less impact than open thoracic fusion.
G. Spinal cord monitoring
1. The current standard of care is spinal cord monitoring using both SSEPs, which will detect many but not all neurologic difficulties, and MEPs, which can detect neurologic injury earlier than SSEPs.
2. Monitoring of the upper extremities with SSEPs can identify positional injury to the upper extremity, which is the most common intraoperative neurologic injury that is reversible.
3. When spinal cord monitoring suggests neurologic injury, either technical problems or real neurologic problems may be responsible.
a. Technical problems
i. Loose electrodes
ii. Use of inhalational agents makes MEPS monitoring difficult.
b. Real neurologic problems
i. If changes occurred following deformity correction, reverse or lessen the correction.
ii. Raise blood pressure
iii. If hematocrit is low, give a blood transfusion.
iv. Give intravenous steroids (eg, solumedrol 30 mg/kg bolus, and 6.5mg/kg × 23 hours).
v. Administer the wake-up test.
vi. If all else fails and if the spine is stable, remove instrumentation.
1. Participating in activities of daily living (ADL) should be encouraged in the early postoperative phase.
2. Besides encouraging ambulation and ADLs, little active physical therapy is indicated.
3. Return to sports is surgeon-dependent.
II. Congenital Scoliosis
A. Overview (epidemiology)
1. Genetics—No specific inheritance pattern; isolated occurrences.
2. Estimated prevalence in general population is 1% to 4%.
1. Three categories—failure of formation, failure of segmentation, and mixed (
Figure 4 and
a. Failure of formation—The mildest form is wedge vertebra, followed by a hemivertebra.
i. Three types of hemivertebrae are fully segmented (disk space present above and below hemivertebra), semisegmented (hemivertebra fused to adjacent vertebra on one side with disk on the other), and unsegmented (hemivertebra fused to vertebra on each side).
ii. Hemimetameric shift is the presence of contralateral hemivertebrae separated by one normal vertebra.
b. Failure of segmentation—Implies bony bars between vertebrae.
i. Block vertebrae have bilateral bony bars.
ii. Unilateral bars cause scoliosis by tethering growth on one side and are thus present at the concavity of the curve.
iii. A unilateral unsegmented bar associated with a contralateral hemivertebra has the worst prognosis for development of scoliosis.
iv. The best prognosis is for the block vertebra (bilateral failure of segmentation).
c. The presence of a congenital vertebral anomaly in the thoracolumbar region with fused ribs has a high risk of progression.
d. Incarcerated hemivertebrae do not cause scoliosis because deficiencies above and below the hemivertebrae compensate.
2. Thoracic insufficiency syndrome (TIS)
a. TIS is defined as the inability of the thorax to support normal respiration or lung growth.
b. It is usually associated with significant scoliosis (idiopathic or congenital), a shortened thorax, rib fusions or rib aplasia, or poor rib growth (Jeunes syndrome).
c. Jarcho-Levin syndrome, extensive congenital fusions of the thoracic spine, is a common cause of TIS, with two important subtypes:
i. Spondylothoracic dysplasia (primarily vertebral involvement)
ii. Spondylocostal dysplasia (fused or missing ribs)
d. Left untreated, TIS can cause significant cardiopulmonary insufficiency or an early demise.
3. Progression of deformity correlates with growth, which is rapid the first 3 years of life.
1. Associated systemic abnormalities are present in up to 61% of patients with vertebral anomalies.
a. Congenital heart defects (26%)
b. Congenital urogenital defects (21%)
c. Limb abnormalities (hip dysplasia, limb hypoplasia, Sprengel deformity)
d. Anal atresia
e. Hearing deficits
f. Facial asymmetry
2. Approximately 38% to 55% of patients with vertebral anomalies present with a constellation of defects that constitute a syndrome, such as VACTERL (vertebral, anal, cardiac, tracheal, esophageal,renal, and limb defects) and Goldenhar syndrome (dysplastic or aplastic ears, eye
[Figure 4. Classification of congenital vertebral anomalies resulting in scoliosis. Defects of segmentation include block vertebra, unilateral bar, and unilateral bar with contralateral hemivertebra.]
[Table 2. Rates of Progression for Specific Anomalies*]
growths or absent eye, asymmetric mouth/chin, usually affecting one side of face).
3. Workup of patients with congenital scoliosis includes renal (MRI or ultrasound) and cardiologic evaluation.
4. Pulmonary function should also be evaluated, with attention to TIS.
5. MRI is indicated for all patients with congenital spinal deformity because 20% to 40% will have a neural axis abnormality (Chiari type 1 malformation, diastematomyelia, tethered spinal cord, syringomyelia, low conus, intradural lipoma).
6. MRI in young children who would require general anesthesia may be delayed if the curve is not progressive or requiring surgery.
7. The presence of chest dysplasia (fused or absent ribs) impacts treatment options.
1. Nonsurgical—Bracing has no effect on congenital scoliosis.
i. Significant progression of scoliosis
ii. Known high risk of progression, such as a unilateral bar opposite a hemivertebra
iii. Declining pulmonary function
iv. Neurologic deficit
i. Poor skin at surgical site
ii. Minimal soft-tissue coverage over spine
iii. Significant medical comorbidities
i. Unilateral unsegmented bars with minimal deformity are best treated with early in situ arthrodesis, either anterior and posterior or posterior alone.
ii. Progressive fully segmented hemivertebrae in children <5 years of age with <40° curve without notable spinal imbalance have traditionally been treated with an in situ anterior and/or posterior contralateral hemiepiphysiodesis with hemiarthrodesis.
iii. Hemivertebra excision is recommended for patients with progressive curve with marked trunk imbalance caused by a hemivertebra. This technique has the best results for patients <6 years of age with flexible curves <40°.
iv. Anterior and/or posterior osteotomy/vertebrectomy approaches are recommended for more severe, rigid deformities, fixed pelvic obliquity, or decompensated deformities that present late.
v. Growing rod constructs may attach to the spine and/or ribs and attempt to control deformity and encourage spinal growth. Better results are reported with lengthening the construct about every 6 months.
vi. TIS—A shortened hemithorax with fused ribs may benefit from an opening wedge thoracostomy, expansion of the hemithorax, and growing implant(s) across the hemithorax.
d. Rehabilitation is usually not needed.
Iatrogenic shortening of spinal column due to fusion
a. Younger age at surgery and more fused levels have a greater impact on growth.
b. The goal of growth constructs is to optimize spinal growth.
Neurologic injury—Can occur secondary to overdistraction or overcorrection, harvesting of segmental vessels, or spinal implant intrusion into the canal.
Soft-tissue problems over the spinal implants
a. Children with congenital scoliosis, especially those with pulmonary compromise, often have insufficient subcutaneous tissue volume to safely pad the implants.
b. Maximation of preoperative nutrition is vital.
The importance of nutrition in this population cannot be overemphasized.
A. Overview (epidemiology)
1. The most common types are postural, Scheuermann (
Figure 5), and congenital (
Figures 6 and
2. Less commonly, kyphosis is secondary to trauma, infection, or spinal instrumentation.
3. The incidence of Scheuermann kyphosis is 1% to 8%, with a male to female ratio between 2:1 and 7:1.
4. Scheuermann kyphosis is defined as thoracic hyperkyphosis caused by three consecutive vertebrae with >5° of anterior wedging (Sorensen's criteria). Increased kyphosis with gibbus on clinical examination may be considered diagnostic.
1. Scheuermann kyphosis
a. Believed to be a developmental error in collagen aggregation leading to disturbance of enchondral ossification of the vertebral end plates; this leads to wedge-shaped vertebra and increased kyphosis.
b. It is most common in the thoracic spine; less common in the lumbar spine.
c. The natural history of Scheuermann kyphosis in adults with mild forms of the disease (mean 71°) is back pain that only rarely interferes with daily activities or professional careers.
[Figure 5. Patient with Scheuermann kyphosis. A, Clinical photograph showing sharp angulation typical of Scheuermann kyphosis. B, Lateral radiograph showing wedging of vertebrae and irregularity of end plates.]
d. More severe deformities (>75°) are more likely to cause severe thoracic pain.
e. Pulmonary compromise is not generally a concern unless kyphosis exceeds 100°.
2. Congenital kyphosis—Divided into four types, with type I and type III associated with the greatest risk of neurologic injury.
a. Type I—Failure of formation. Rate of progression for this type is 7° to 9°/year.
b. Type II—Failure of segmentation. Rate of progression is 5° to 7°/year.
c. Type III (mixed)—Has worst prognosis for sagittal plane deformity.
d. Type IV—Rotatory/congenital dislocation of spine.
1. Normal thoracic kyphosis is 20° to 45° with no kyphosis at the thoracolumbar junction.
2. The patient usually presents because of cosmetic concerns or pain, which can be at the thoracic region or in the hyperlordotic lumbar spine.
a. Thoracolumbar kyphosis is typically painful, whereas thoracic kyphosis is typically not painful.
[Figure 6. Lateral radiograph demonstrating congenital kyphosis with failure of segmentation.]
[Figure 7. Sagittal MRI demonstrating congenital kyphosis primarily from posterior hemivertebra, with block vertebra immediately cephalad.]
b. Patients with congenital and Scheuermann kyphosis will clinically demonstrate an acute gibbus at the site of pathology.
3. Postural kyphosis presents a more gentle, rounded contour (without gibbus) of the back with up to 60° of kyphosis.
4. Classic plain radiographic findings in Scheuermann kyphosis are vertebral end plate abnormalities, loss of disk height, Schmorl nodule, and wedge vertebra. The lumbar spine needs to be evaluated to rule out concomitant spondylolisthesis.
5. Magnetic resonance imaging
a. MRI is indicated for all patients with congenital kyphosis, which has a 56% incidence of intraspinal anomalies.
b. It may be indicated preoperatively in Scheuermann kyphosis to rule out potential thoracic disk herniation, epidural cyst, or spinal stenosis, which may cause neurologic symptoms at the time of deformity correction.
a. Congenital kyphosis—Bracing is ineffective.
b. Scheuermann kyphosis
i. Bracing can be effective if >1 year of growth remains and kyphosis is between 50° and 70° with the apex at or below T7.
ii. Bracing is continued for a minimum of 18 months.
iii. Pain can respond to physical therapy and NSAIDs.
iv. Patient noncompliance with bracing is common.
i. Surgery is indicated for most patients with type II (failure of segmentation) or type III (mixed) kyphosis, especially those with neurologic deficits.
ii. For those with type I (failure of formation), an indication for surgery is progressive local kyphosis >40° or neurologic symptoms.
Scheuermann kyphosis—Relative indications for surgery:
i. Kyphosis >75°
ii. Deformity progression
iv. Neurologic deficits
v. Significant pain unresponsive to nonsurgical management
Contraindications—Asymptomatic Scheuermann kyphosis in a child without cosmetic concerns.
i. Congenital kyphosis—For children with failure of segmentation who are <5 years of age with <55° kyphosis, posterior fusion is recommended to stabilize the kyphosis and permit some correction. Anterior decompression (which may be performed through a posterior approach) is performed for compromised neural structures.
ii. Scheuermann kyphosis surgery—Posterior spinal fusion with instrumentation. Anterior release has been recommended for deformities that do not correct to >50° on hyperextension lateral radiograph over an apical bolster. Newer thoracic pedicle screw constructs with multiple posterior osteotomies may obviate the need for anterior releases. Traditional recommendations are to limit correction to <50% of deformity to prevent proximal or distal junctional kyphosis or implant pull-out.
Rehabilitation—Generally not needed.
1. Neurologic injury (paralysis, nerve root deficit) can occur due to mechanical impingement or stretch of cord, by spine implants or bony/soft-tissue structure, or vascular.
2. Anterior approaches to the thoracic spine can injure the artery of Adamkiewicz, the main blood supply to the T4-T9 spinal cord, generally arising variably from T8-L2 on the left.
3. Junctional kyphosis occurs in 20% to 30% of patients, although this is usually not clinically significant.
A. Overview (epidemiology)
1. Incidence of spondylolysis is 5% (males > females). Incidence is 53% in Eskimos.
2. 25% of patients with spondylolysis have associated spondylolisthesis.
3. Of patients with isthmic spondylolisthesis, males are affected more commonly than females, but females are four times more likely to develop high-grade slip.
4. Primarily affects L5 (in 87% to 95% of patients); less frequently, L4 (in up to 10%) and L3 (in up to 3%).
1. Spondylolysis is an acquired condition presumed to be a stress fracture through the pars interarticularis.
2. Spondylolisthesis is anterior slippage of one vertebra relative to another and is most common in the lumbar spine.
3. Progression is associated with the adolescent growth spurt, lumbosacral kyphosis (slip angle
Figure 8. Grade IV dysplastic (Wiltse type I) spondylolisthesis of L5-S1 in a 9-year-old girl. A, Clinical photograph. Note the position of flexion of her hips and knees. B, Popliteal angle measurement of 55° secondary to contracture of hamstring muscles. C, Lateral weight-bearing radiograph of the lumbosacral spine of the same patient, illustrating high-grade dysplastic spondylolisthesis with severe lumbosacral kyphosis (arrows).]
>40°), higher Meyerding grade (>II or >50% translation), younger age, female sex, dysplastic posterior elements, and dome-shaped sacrum.
4. Dysplastic spondylolistheses have an intact posterior arch, increasing the risk of neurologic symptoms due to entrapment of the cauda equina and the exiting nerve roots (Figure 8).
1. Back pain is usually localized to the lumbosacral area but may run down the legs.
2. Pain is exacerbated by lumbar extension activities and improved with rest.
3. Physical examination findings include paraspinal muscle spasms, tight hamstrings, and limited lumbar mobility.
a. High-grade spondylolisthesis can produce a waddling gait and hyperlordosis of the lumbar spine.
b. The nerve root most commonly affected by a spondylolisthesis at L5-S1 is L5.
a. Oblique radiographs, in addition to AP and lateral views, may aid in identifying pars defects; this has been described as the "Scotty dog sign."
b. In high-grade slips with significant angulation of the cephalad vertebra, a Napoleon's hat sign may be seen on the AP views.
c. Dynamic flexion-extension lateral radiographs can be helpful in assessing translational stability.
Figure 9. Patient with spondylolytic defect of the pars interarticularis of L5. Lateral weight-bearing (A) and supine oblique (B) radiographs demonstrating the defect (circle, arrow). C, Axial CT image through the L5 vertebra, demonstrating the bilateral spondylolytic defects.]
Figure 10. Diagrams illustrating the measurements used in the Meyerding classification. A, The Meyerding classification is used to quantify the degree of spondylolisthesis. Grade I is 0% to 25% slip, grade II is 26% to 50% slip, grade III is 51% to 75% slip, and grade IV is 75% to 99% slip. A = width of the superior end plate of S1, a = distance between the posterior edge of the inferior end plate of L5 and the posterior edge of the superior end plate of S1. B, Slip angle A quantifies the degree of lumbosacral kyphosis. A value >50° correlates with a significantly increased risk of progression of spondylolisthesis.]
d. Single photon emission CT (SPECT) is highly sensitive for pars defects (Figure 9).
e. MRI is suboptimal for evaluating pars defects but has a role in assessing nerve entrapment.
1. Wiltse system
a. Describes types based on etiology: dysplastic (congenital, type 1), isthmic (acquired, type 2), degenerative, traumatic, pathologic, iatrogenic.
b. The isthmic type (type 2), which occurs 85% to 95% of the time at L5 and 5% to 15% at L4, is most common in adolescents.
2. Meyerding classification (Figure 10)
a. Based on amount of forward slippage of superior vertebra on inferior vertebra and reported in quadrants.
b. Grade V is spondyloptosis, or 100% translation anteriorly of the superior vertebra.
a. Asymptomatic patients with spondylolysis and grade I or II spondylolisthesis do not require treatment or activity restrictions.
b. Symptomatic patients (spondylolysis and grade I or II spondylolisthesis) are treated with lumbosacral orthoses for up to 4 to 6 months.
a. Indications for surgery
i. Uncontrolled pain (after nonsurgical management)
ii. Neurologic symptoms (ie, radicular symptoms or cauda equina syndrome)
iii. Grade III or higher slip or progressive slip to 50% slip
i. Spondylolysis can be treated with pars repair. If disk desiccation is present (dark disk), L5-S1 fusion should be performed.
ii. Posterolateral fusion (with or without instrumentation) may be performed for spondylolysis and spondylolisthesis. With uninstrumented fusions, the deformity may progress over many years. Pedicle screw constructs may increase fusion rates and decrease postoperative slip progression.
iii. In the presence of neurologic deficit, decompression is generally recommended, although neurologic improvement has been demonstrated by in situ fusion alone.
iv. Indications for reduction are controversial, with no universally accepted guidelines. Reduction of spondylolistheses >50% is associated with L5 nerve root stretch and neurologic injury.
1. Cauda equina syndrome (rare) is most likely to occur in type 1 (dysplastic/congenital) slips, with the intact posterior neural arch trapping the sacral roots against the posterosuperior corner of the sacrum. This may occur without surgery.
2. Implant failure (rare)
3. Pseudarthrosis (occurs in up to 45% of high-grade fusions without implants, up to 30% in high-grade slips with posterior instrumentation, rare in high-grade slips with circumferential fusion)
4. Postoperative slip progression
5. Pain (occurs in approximately 14% of patients at 21 years postoperatively)
V. Cervical Spine Abnormalities
A. Overview (epidemiology)
1. In Down syndrome, 61% of patients have atlanto-occipital hypermobility and 21% have atlantoaxial instability; the subaxial cervical spine is not affected.
2. Klippel-Feil syndrome is characterized by failure of segmentation in the cervical spine with a short, broad neck, torticollis, scoliosis, low hairline posteriorly, high scapula, and jaw anomalies. Sprengel deformity is seen in 33% of patients with Klippel-Feil.
3. Intervertebral disk calcification is most common in the cervical spine.
B. Pathoanatomy of os odontoideum
1. The odontoid develops from two ossification centers that coalesce at <3 months of age.
2. The tip of the dens is not ossified at birth but appears at 3 years of age and fuses to the dens by age 12 years.
3. Os odontoideum is usually due to nonunion and may result in atlantoaxial instability. The odontoid is separated from the body of the axis by a synchondrosis (appears as "cork in a bottle"), which usually fuses by age 6 to 7 years.
1. Physical examination findings in patients with basilar invagination include loss of upper/lower extremity strength, spasticity, and hyperreflexia. Patients with intervertebral disk calcification present with neck pain but have normal neurologic examination.
2. Radiographic imaging of the cervical spine includes primarily plain AP, lateral, and odontoid views.
a. Basilar invagination is evaluated on the lateral view and is defined by protrusion of the dens above McRae's line or 5 mm above McGregor's line.
b. Atlantoaxial instability is present when the ADI (atlanto-dens interval) is >5 mm (
c. Instability is also evaluated with the Powers ratio (Figure 11), which is the ratio of the length of the line from the basion to the posterior margin of the atlas divided by the length from the opisthion to the anterior arch of the atlas. A normal Powers ratio is <1.0.
d. Space available for spinal cord (SAC) should be ≥13 mm (Figure 11).
e. At the level of the odontoid, the rule of thirds prevails, with the odontoid taking one third of the inner diameter of C1, the cerebrospinal fluid taking one third, and the spinal cord taking the final third of the distance.
1. Basilar invagination
a. Commonly associated with Klippel-Feil syndrome, hypoplasia of the atlas, bifid posterior arch of the atlas, and occipitocervical synostosis.
b. Also commonly found in systemic disorders such as achondroplasia, osteogenesis imperfecta, Morquio syndrome, and spondyloepiphyseal dysplasia.
c. Motor and sensory disturbances occur in 85% of individuals with basilar invagination. Patients may present with headache, neck ache, and neurologic compromise.
2. In occipitocervical synostosis, clinical findings are a short neck, low posterior hairline, and limited neck range of motion. Atlantoaxial instability is present in 50%.
[Figure 11. Upper cervical spine and occiput (C1-C3). A, Powers ratio = BC/AO. B = basion, C = posterior arch of the atlas, A = anterior arch of the atlas, O = opisthion. B, Basion-dental interval (BDI) and basion-axial interval (BAI) each should measure <12 mm. C, ADI and SAC. Atlantoaxial instability should be suspected with an ADI >5 mm. If the ADI is ≥10 to 12 mm, the SAC becomes negligible and cord compression occurs.]
3. Odontoid anomalies range from aplasia to varying degrees of hypoplasia, which secondarily causes atlantoaxial instability.
4. Congenital muscular torticollis is associated with developmental hip dysplasia (5%). Its etiology is presumed secondary to compartment syndrome.
5. The etiology of torticollis also includes ophthalmologic, vestibular, congenital, and traumatic causes as well as tumors. If a tight sternocleidomastoid is not present, look for other causes.
6. Atlantoaxial rotatory displacement (AARD)
a. Ranges from mild displacement to fixed, subluxated C1 on C2. Most often caused by upper respiratory infection (Grisel syndrome) or trauma.
b. CT is used to confirm the diagnosis and rule out grades III and IV AARD, which are associated with neurologic injury and sudden death.
7. Patients with Morquio syndrome commonly have atlantoaxial instability due to odontoid hypoplasia.
a. Intervertebral disk calcification is treated with analgesics.
i. Biopsy and antibiotics are not needed.
ii. Calcifications usually resolve over 6 months.
b. Congenital muscular torticollis—Initial treatment is passive stretching.
c. AARD is initially managed with NSAIDs, rest, soft collar.
d. In patients with Down syndrome who have ADI >5 mm without symptoms, restrict from stressful weight bearing on head, such as gymnastics and diving.
i. Basilar invagination
ii. Occipitocervical synostosis with atlantoaxial instability
iii. Odontoid anomalies: neurologic involvement, instability of >10 mm on flexion-extension radiographs, persistent neck symptoms
iv. Congenital muscular torticollis if limitation is >30° or condition persists >1 year.
v. Klippel-Feil—Not clearly defined.
vi. In patients with Down syndrome, ADI >5 mm with neurologic symptoms or >10 mm without symptoms
vii. Morquio and spondyloepiphyseal dysplasia—>5 mm of instability (regardless of symptoms)
i. Basilar invagination is treated with decompression and fusion to C2 or C3.
ii. Occipitoaxial synostosis requires atlanto-axial reduction with fusion of occiput-C1 complex to C2. If neural impairment exists, then consider adding decompression to fusion.
iii. Odontoid anomalies with instability undergo C1-2 fusion.
iv. Congenital muscular torticollis has been effectively treated with distal bipolar release of sternocleidomastoid.
v. Atlantoaxial rotatory displacement—If persistent for >1 week and reducible, use head halter traction (at home or in hospital). If symptoms persist for >1 month, consider a halo or rigid brace. C1 to C2 fusion may be indicated if neurologic involvement or persistent deformity is present.
1. Halo complications are common.
a. Anterior pins most commonly injure the supraorbital nerve.
b. More pins (6 to 12) with less insertional torque (≤5 inch-pounds) are used in young children.
c. Head CT is helpful to measure calvarial thickness and optimal pin placement.
d. The sixth cranial nerve (abducens) is the most commonly injured with halo traction, which is seen as a loss of lateral gaze. If neurologic injury is noted with halo traction, remove traction.
2. Nonunions and up to 25% mortality rate are reported with C1-C2 fusion in patients with Down syndrome.
3. Posterior cervical fusions have a high union rate with iliac crest bone grafting, but the union rate is reported to be much lower with allograft.
VI. Spine Trauma
A. Overview (epidemiology)
1. Injuries to the cervical spine account for 60% of pediatric spinal injuries.
2. Mortality from cervical injury in pediatric trauma victims is 16% to 17%.
3. Across all pediatric age groups, the most common mechanisms of injury involve motor vehicle accidents. Toddlers and school-age children are injured most commonly in falls, and adolescents also suffer sports-related injuries.
1. Children younger than 8 years have an increased risk of cervical spine injuries due to their larger head-to-body ratio, greater ligamentous laxity, and relatively horizontal facet joints.
Table 3. Normal Radiographic Findings Unique to the Pediatric Cervical Spine]
2. In children with cervical spine injuries, 87% of those who are <8 years of age have injuries at C3 or higher. These children also have a higher mortality rate than do older children, with rates ranging from 17% at C1 to 3.7% at C4.
3. The immature spinal column can stretch up to 5 cm without rupture; the spinal cord ruptures at 5 to 6 mm of traction.
4. In children with cervical spine injuries, 33% will manifest evidence of neurologic deficit.
5. Injuries to other organ systems occur in 42% of children with spine injuries.
1. Initial management—Transport on backboard with cut-out for occiput or mattress to elevate the body, to prevent inadvertent flexion of the cervical spine due to the child's disproportionately large head.
2. Physical examination
a. A detailed neurologic examination should be conducted, including sensation (look for sacral sparing), motor function, and reflexes (absence of anal wink indicates spinal shock).
b. Upper cervical spine injuries should be suspected in young children with facial fractures and head trauma.
a. Initial imaging should be plain radiographs of the injured region (Table 3 and
i. Atlantoaxial instability is evaluated using the ADI, which should be <5 mm in children. When the ADI >10 mm, all ligaments have failed, creating cord compression due to negligible space available for the spinal cord (SAC).
[Figure 12. Radiograph demonstrating pseudosubluxation of C2-C3. The Swischuk line (white line) connects the spinolaminar junction of C1 to C3. As long as the spinolamiar junction of C2 is no more than 1 mm anterior to this line, the subluxation is physiologic.]
ii. On a lateral radiograph, the retropharyngeal space should be <6 mm at C2 and <22 mm at C6. These spaces may be enlarged due to crying, however, and therefore this is not necessarily a sign of underlying injury in children.
iii. Instability of the subaxial cervical spine should be suspected with intervertebral angulation of >11° or translation of >3.5 mm.
iv. It is crucial to always visualize the C7-T1 junction on the lateral view.
b. Three-dimensional imaging—CT and MRI help to assess injury and amount of spinal canal intrusion.
c. Atlanto-occipital junction injuries are assessed with the Powers ratio, the C1-C2:C2-C3 ratio, and the BAI (basion-axial interval) (Figure 11).
i. The Powers ratio is determined by the ratio of the line from the basion to the posterior arch of the atlas and a second line from the opisthion to the anterior arch of the atlas; a ratio >1.0 or <0.55 represents a disruption of the atlanto-occipital joint.
ii. The C1-C2:C2-C3 ratio (interval between the posterior arches) is <2.5 in normal children.
Figure 13. Lateral radiograph (A) and CT scan (B) of a 5-year-old boy who sustained a hangman's fracture (arrows) in a motor vehicle accident.]
d. The BAI is the distance from the basion to the tip of the odontoid and should be <12 mm in all children.
a. Atlanto-occipital junction injuries are highly unstable ligamentous injuries that are rare but commonly fatal. Common mechanisms are motor vehicle accidents and pedestrian-vehicle collisions.
b. Atlas fractures (also known as Jefferson fractures) are uncommon injuries that are usually due to axial loading.
i. Neurologic dysfunction is atypical.
ii. Widening of lateral masses of >7 mm beyond the borders of the axis on the AP view indicates injury to the transverse ligament
c. Atlantoaxial injuries are usually ligamentous injuries to the main stabilizers (transverse ligament) or secondary stabilizers (apical and alar ligaments).
d. Odontoid fractures usually occur through synchondrosis by a flexion moment causing anterior displacement.
e. Hangman's fractures are usually due to hyperextension causing angulation and anterior subluxation of C2 on C3 (Figure 13).
f. Lower (C3 through C7) cervical spine injuries are more common in adolescents.
a. Flexion injuries result in compression or burst fractures.
i. Compression fractures rarely exceed more than 20% of vertebral body.
ii. With >50% loss of vertical height, consider a burst fracture and obtain a CT scan.
b. Distraction and shear injuries are highly unstable and usually associated with spinal cord injury.
c. Chance fractures are caused by hyperflexion over automobile lap belts and are frequently associated with intra-abdominal injuries.
d. Spinal cord injury without radiographic abnormality (SCIWORA)
i. MRI is the study of choice.
ii. SCIWORA is the cause of paralysis in approximately 20% to 30% of children with injuries of the spinal cord.
iii. Approximately 20% to 50% of patients with SCIWORA have delayed onset of neurologic symptoms or late neurologic deterioration.
iv. Children <10 years of age are more likely to have permanent paralysis than older children.
i. Intervertebral disk calcification—Treated with rest and NSAIDs.
ii. Atlas fractures—Treated with cervical collar or halo.
i. Compression fractures—Bracing for 6 weeks.
ii. Burst fractures—Bracing if stable.
iii. Chance fractures with <20° of segmental kyphosis—Treated in a hyperextension cast.
iv. SCIWORA—Immobilization for 6 weeks to prevent further spinal cord injury.
i. Craniocervical instability
ii. Atlantoaxial instability with ADI >5 mm
iii. Displaced odontoid fracture
iv. Displaced and angulated hangman's fracture
v. Thoracolumbar burst fractures with neurologic injury and canal compromise
vi. Distraction and shear injuries with displacement
vii. Chance fractures that are purely ligamentous injuries and bony injuries with >20° kyphosis
i. Craniocervical instability is treated with an occiput-to-C2 fusion with halo stabilization, preferably with internal fixation.
ii. Atlantoaxial instability requires a C1-C2 posterior fusion with transarticular C1-C2 screw with a Brooks-type posterior fusion or lateral mass screws.
iii. Odontoid—Reduction of displacement with extension or hyperextension with halo immobilization for 8 weeks.
iv. Hangman's fractures with minimal angulation and translation can be treated with closed reduction in extension with immobilization in a Minerva cast or halo device for 8 weeks. Fractures with significant angulation or translation require a posterior fusion or anterior C2-C3 fusion.
v. Halo placement—In toddlers and children <8 years of age, use more pins (8 to 12) with only finger tightness (2 to 4 inch-pounds). Anterior pins should be placed lateral enough to avoid the frontal sinus and supraorbital and supratrochlear nerves. Place pins anterior enough to avoid temporalis muscle. The posterior pins should be placed on the opposite side of the ring from the anterior pins.
vi. Thoracolumbar burst fractures with canal compromise require canal decompression, fusion, and instrumentation. Indirect canal decompression is accomplished by surgical distraction of injured level.
vii. Distraction and shear injuries are treated with reduction with decompression, instrumentation, and arthrodesis.
viii. Chance injuries that are purely ligamentous injuries should be surgically stabilized with instrumentation and arthrodesis. Bony injuries with >20° kyphosis or inadequate reduction are treated with posterior compression instrumentation and arthrodesis.
1. Os odontoideum
a. Caused by nonunion of an odontoid fracture that may have episodic or transient neurologic symptoms.
b. Instability when >8 mm of motion; requires C1-2 fusion.
2. Posttraumatic kyphosis usually does not remodel and may worsen.
4. Implant failure
VII. Other Conditions
Pathoanatomy—Presumed infection likely begins by seeding the vascular vertebral end plate and then extending into the disk space.
ii. Back pain
iii. Abdominal pain
iv. Refusal to ambulate
v. Painful limp
Figure 14. A 3-year-old girl with a 2-week history of irritability and refusal to walk for 2 days. PA (A) and lateral (B) radiographs demonstrate disk-space narrowing at L3-4 consistent with discitis.]
vi. Lower extremity discomfort
b. 25% will be febrile.
c. Laboratory studies of ESR and CRP will be elevated.
d. Radiographs can demonstrate disk-space narrowing with vertebral end plate irregularities (Figure 14). Further imaging generally is not needed.
a. Typical organism is Staphylococcus aureus.
b. Must consider Langerhans cell histiocytosis (the "great imitator").
i. Typically parenteral antibiotics (to cover S aureus) for 7 to 10 days; then switch to oral antibiotics for several more weeks.
ii. If the discitis fails to respond to antibiotics, biopsy should be performed for cultures and pathologic tissue evaluation.
i. Indications—Paraspinal abcess in the presence of neurologic deficit; unresponsive to nonsurgical care.
ii. Contraindications—Standard discitis.
iii. Procedures—Culture, irrigation and debridement.
Figure 15. A 7-year-old boy was admitted with pain and a stiff neck. Lateral radiograph shows calcification of the disk space between C2 and C3.]
a. Long-term disk-space narrowing
b. Intervertebral fusions
c. Back pain
Pearls and pitfalls—Think of salmonella in the setting of sickle cell anemia.
B. Cervical disk calcification
1. Presents with neck pain universally.
2. Radiographs show calcification of the cervical disk (Figure 15).
3. May have fever and elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).
a. Observation—Biopsy and surgery are not indicated.
b. Mean time to resolution is just over 1 month.
C. Sacroiliac joint septic arthritis
1. Epidemiology—More common in children >10 years of age.
a. S aureus is most common.
b. Think of salmonella in association with sickle cell anemia.
a. Tenderness is usually present directly over the sacroiliac joint and the FABER test (hip flexed, abducted, externally rotated) reproduces pain.
b. MRI or bone scan confirms the diagnosis; needle biopsy is technically possible but not necessary.
VIII. Back Pain
A. Overview (epidemiology)
1. More than 50% of children will experience back pain by age 15 years. In 80% to 90%, the pain resolves within 6 weeks.
2. Differential diagnosis of back pain is shown in
1. In children younger than 10 years, consider serious underlying pathology, although standard mechanical back pain is still most common.
2. Older children and adolescents will commonly suffer "adult" low back pain.
3. Spinal deformities (scoliosis and kyphosis) can cause pain.
4. Consider intra-abdominal pathology such as pyelonephritis, pancreatitis, and appendicitis.
5. Studies suggest that more weight in a backpack is associated with a higher incidence of back pain.
a. Pain at night is traditionally associated with tumors.
b. Visceral pain is not relieved by rest or exacerbated by activity.
A detailed musculoskeletal, abdominal, and neurologic examination is necessary.
3. Imaging studies
a. Plain radiographs
b. Technetium Tc 99m bone scan is helpful to localize tumor, infection, or fracture.
c. CT is best for bone problems (spondylolysis).
d. MRI is recommended for any neurologic signs or symptoms.
[Table 4. Differential Diagnosis of Back Pain in Children]
Laboratory studies such as complete blood counts, CRP, ESR, and a peripheral smear are indicated for patients with back pain and constitutional symptoms.
1. Possible specific causes include discitis, spinal deformity (scoliosis and kyphosis), neoplasms, spondylolysis/spondylolisthesis, disk herniations, and vertebral apophyseal end plate fracture.
2. Posteriorly, common tumors include osteoid osteoma (
Figure 16), osteoblastoma, and aneurysmal bone cyst (
Figure 17). Anteriorly, histiocytosis X has a predilection for the vertebral body, causing vertebrae plana (
3. The most common malignant cause of back pain is leukemia.
1. Nonsurgical—Osteoid osteomas are initially treated with NSAIDs and observation.
i. Lumbar disk herniation—If unresponsive to nonsurgical management for a minimum of 6 weeks or if neurologic symptoms are present.
[Figure 16. Axial CT scan at C5 in a 12-year-old girl with an osteoid osteoma of the left pedicle. The arrow indicates the center of the lesion (nidus). The nonlesional, reactive sclerotic bony rim around the nidus (arrowhead) is characteristic of osteoid osteoma on CT.]
[Figure 17. AP radiograph of the thoracic spine demonstrating the "winking owl" sign in an 8-year-old girl with an aneurysmal bone cyst at T5. The left pedicle of T5 is missing (arrow).]
[Figure 18. Lateral radiograph of the spine showing vertebra plana at L2 in a 5-year-old girl with Langerhans cell histiocytosis. The collapse of the vertebral body of L2 (arrow) without soft-tissue extension or loss of disk-space height is characteristic of Langerhans cell histiocytosis.]
ii. Osteoid osteomas—If nonsurgical pain management fails. Radioablation is not commonly used in the spine for fear of risking neurologic injury.
iii. Osteoblastomas—Surgical treatment is always indicated because these tumors do not respond to nonsurgical interventions.
b. Procedures—Benign bone lesions can be marginally excised.
F. Red flags for pathologic back pain
a. Pain is well localized. Positive finger test: patient points to pain in one location with one finger.
b. Pain becomes progressively worse over time.
c. Pain is not associated with activities and is present at rest or nighttime.
d. Bowel or bladder incontinence
2. Physical examination
a. Tight hamstrings—Popliteal angle >50°.
b. Localized bony tenderness
c. Neurologic abnormalities
Top Testing Facts
1. In patients with idiopathic scoliosis curves that are not standard, such as a left primary thoracic curve, an MRI is indicated because intraspinal anomalies are common in this population.
2. The general indication for surgical treatment in patients with adolescent idiopathic scoliosis is a curve >45° to 50°.
1. Congenital scoliosis is associated with a significant risk of cardiac and renal anomalies; therefore, a cardiac workup and renal ultrasound are generally indicated prior to surgery.
2. Congenital scoliosis is also associated with intraspinal pathology in up to 40% of patients, so a preoperative MRI is indicated.
1. Do not try to correct more than 50%.
2. The lower end of the instrumentation should include the first two lordotic vertebrae or risk junctional kyphosis.
3. When segmental pedicle screws are used in combination with multiple posterior osteotomies, anterior approaches can generally be avoided.
4. Scheuermann kyphosis is defined as thoracic hyperkyphosis caused by three consecutive vertebrae with >5° of anterior wedging.
Spondylolysis and Spondylolisthesis
1. Spondylolysis or spondylolisthesis occurs in 5% of the population, and most are asymptomatic.
2. Even though a patient has spondylolysis, continue to look for other causes of back pain if the clinical picture is not typical.
3. The end point of treatment in a slip <50% is absence of pain, not necessarily radiographic demonstration of healing.
4. Reduction of the slip >50% is associated with L5 nerve root stretch and neurologic injury, and should generally be avoided.
1. Ligamentous injuries seen in a purely soft-tissue Chance fracture do not heal and usually require surgical stabilization.
2. Bony fractures without significant angulation may be treated nonsurgically.
3. Ecchymosis in the distribution of the seatbelt should raise suspicion of a Chance fracture and/or interabdominal injuries.
4. Children younger than 8 years tend to have cervical injuries C3 and above; children older than 8 years tend to have injuries below C3.
5. On radiographs, the atlanto-dens interval should be <5 mm in children, and the retropharyngeal space should be <6 mm at C2 and <22 mm at C6.
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