Miller-Pediatric Spine Flashcards
Review important markers for Idiopathic Adolesent Scoliois
Know the indications to order an MRI with AIS
MRI indications:
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Left thoracic curves
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Painful or rapidly progressing scoliosis
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Apical kyphosis of the thoracic curve
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Juvenile-onset scoliosis (onset before age 10 years)
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Neurologic signs or symptoms
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Congenital abnormalities
Review Peak Height Velocity
General Overview for AIS
Onset after 10 years of age
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Likely multifactorial cause
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May be related to a hormonal, brainstem, or proprioception disorder
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Most patients have a positive family history but variable expression.
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Diagnosis
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School screening mandated by several states
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Rotational deformities noted on the Adams forward bend test (assessed with scoliometer)
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Threshold level of 7 degrees is thought to be an acceptable compromise between overreferral and a false-negative diagnosis and correlates with a 20-degree coronal curve.
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Shoulder elevation, waistline asymmetry, trunk shift, LLD, rib rotational deformity (rib hump), and prominent scapula
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Neurologic findings should be normal.
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Abnormal findings, especially asymmetric abdominal reflexes, should prompt an MRI study.
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Cavus feet should also prompt MRI to assess for intraspinal abnormalities.
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Imaging studies
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Standing full-length posteroanterior radiograph
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Cobb method used to measure magnitude of curves (Fig. 3.24)
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Assessment for Risser sign (ossification of the iliac crest apophysis)
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Stable vertebra: most proximal vertebra that is the most closely bisected by the center sacral vertical line (CSVL)
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End vertebrae: the most tilted vertebrae
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Neutral vertebra: the vertebra that has no rotation in the axial plane
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Lateral radiograph
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Hypokyphosis of thoracic spine and hypolordosis of lumbar spine typically seen
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If hyperkyphosis of the thoracic spine is observed, MRI should be considered.
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Spondylolisthesis at the level of L5–S1 should be sought.
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MRI indications:
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Left thoracic curves
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Painful or rapidly progressing scoliosis
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Apical kyphosis of the thoracic curve
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Juvenile-onset scoliosis (onset before age 10 years)
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Neurologic signs or symptoms
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Congenital abnormalities
What are the risk factors for curve progression with AIS
Risk of progression is related to curve size and remaining skeletal growth, which can be difficult to assess.
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Curves greater than 20 degrees in very young patients
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Thoracic curves greater than 45–50 degrees at skeletal maturity are likely to progress during adulthood.
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Lumbar curves may progress at a lower threshold.
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Peak height velocity (PHV) (Fig. 3.26)
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Best predictor for progression
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Occurs during Risser stage 0, which makes the Risser sign less useful
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Occurs before menarche
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Closure of the olecranon apophysis correlates with PHV
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Modified Tanner-Whitehouse RUS (radius-ulna–short bones) score of 3 (the majority of digits are capped and the metacarpal epiphyses are wider than their metaphyses) correlates with PHV. Patients with a curve of 30 degrees at this stage have a nearly 100% chance of progressing to a range requiring surgery.
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Review the treatment options for AIS
Treatment
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Depends on the likelihood of curve progression
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Observation
- Skeletally immature patients with curves less than 20–25 degrees
- Skeletally mature patients with curves less than 45 degrees
Bracing
Goal: to halt or slow curve progression in skeletally immature patients (Risser stages 0 to 2); however, bracing does not reverse the curve.
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Indications: curves of more than 25 degrees or of 20 degrees with documented progression
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Types of braces:
Milwaukee brace (cervicothoracolumbosacral orthosis [CTLSO]); rarely used
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Boston underarm thoracolumbosacral (TLSO) orthosis
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For curves with the apex at T8 or below
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Thoracic lordosis or hypokyphosis is a relative contraindication.
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Bracing has been shown to be less effective in boys and overweight patients.
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Some writers recommend 18 hours/day in patients at Risser stage 0.
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Effectiveness of bracing in patients with idiopathic scoliosis is “dose dependent”; 90% effective when worn more than 12–13 hours/day
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Surgery
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Goals
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Prevent curve progression and obtain solid fusion
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Obtain and maintain correction in the coronal, axial, and sagittal planes while avoiding complications
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Posterior instrumentation and fusion
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Segmental instrumentation with pedicle screws (most common), hooks, or wires connected to rods
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Pullout strength increased by using larger screws and longer screws, tapping 1 mm less than screw diameter, and using “straightforward” insertion technique
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Correction of deformity and arthrodesis (fusion)
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Anterior instrumentation and fusion
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Uncommon as single approach but useful in two cases:
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Single thoracic fusion, especially if hypokyphosis is present and if fusion levels can be saved
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Single thoracolumbar/lumbar fusion
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Indications for use in combination with posterior approach:
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Very young patients: triradiate cartilage open; used to prevent crankshaft phenomenon
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Large or stiff curves: to improve flexibility, usually for curves of more than 75 degrees. However, the use of pedicle screws and posterior osteotomies may obviate this.
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Fusion levels
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Determining levels is complex and based on many factors.
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Main goal: to minimize the number of fusion levels while achieving good coronal and sagittal balance
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Generally the fusion should:
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Include structural curves
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Include nonstructural lumbar curves that are:
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Greater than 45 degrees
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Associated with significant rotation or translation
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Fusion to T2 proximally when:
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Left shoulder is elevated
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T1 tilt is greater than 5 degrees
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Proximal thoracic curve has significant rotation
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For Lenke 1 and 2 curves:
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A modifier: fusion distally to vertebra touched by CSVL unless L4 is tilted to the right (fuse one or two levels distally)
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B modifier: fusion distally to stable vertebra
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Lenke 3 through 6 curves:
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Fusion to distal end vertebra
Review the surgical complications with AIS
Infection (1.2%–1.3%)
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Acute
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S. aureus most common
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Irrigation and débridement and antibiotic suppression usually required until fusion if infection is deep
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Delayed
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Slow-growing organisms: Propionibacterium acnes, Staphylococcus epidermidis
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Treatment: removal of implants, check for pseudarthrosis, antibiotics
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Pseudarthrosis: (1%–3%)
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Manifests with pain, fractured rod
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Difficult to visualize with imaging studies
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Treatment: compression instrumentation bone grafting
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Neurologic deficits (0.5%–0.7%)
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Usually nerve root or incomplete spinal cord injury
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Implant related: instrumentation placed in canal or foramen
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Blood vessel–related: during correction
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Intraoperative spinal cord monitoring is crucial.
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If changes occur intraoperatively, the surgical team should check leads, raise blood pressure, transfuse, reverse steps of surgery, and reassess.
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If neurologic responses are still diminished, implants should be completely removed.
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Crankshaft phenomenon
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Continued anterior spinal growth after posterior fusion in skeletally immature patients
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Increased rotation and deformity of the spine
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Can be avoided by anterior discectomy and fusion coupled with posterior spinal fusion
General review of Early Onset Scoliosis
The Scoliosis Research Society defines early-onset scoliosis (EOS) as scoliosis diagnosed before age 10 years.
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Comprises a heterogeneous group, including congenital scoliosis and infantile and juvenile idiopathic scoliosis; see individual sections for treatment options.
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Thoracic insufficiency syndrome
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Inability of the thorax to support normal respiration or lung growth
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Causes
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Severe congenital scoliosis with rib fusions
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Jarcho-Levin syndrome: extensive vertebral and rib fusions
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Jeune syndrome or asphyxiating thoracic dystrophy: rib dysplasia causing a shortened and narrow thorax
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Diagnosis
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Clinical signs of respiratory insufficiency
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Loss of chest wall mobility as demonstrated by the thumb excursion test
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Worsening indices of three-dimensional thoracic deformity
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Radiographic studies: measurement of T1–12 height
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CT scans: lung volumes
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Pulmonary function tests: Relative decline in percentage of predicted vital capacity
Define Juvenile Idiopathic Scoliosis
Definition: idiopathic scoliosis that manifests between 4 and 10 years of age
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Presentation: similar to that of adolescent scoliosis in terms of manifestations and treatment
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Right thoracic curve most common
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Differences from adolescent idiopathic scoliosis
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Higher risk of progression, up to 95% in one study
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Less likely to respond to bracing
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More likely to require surgical treatment
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Rate of spinal cord abnormality: 25%
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MRI should routinely be obtained.
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Treatment
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Observation: curves less than 25 degrees
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Nonoperative treatment: curves between 25 and 45 degrees
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Bracing
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Stiff, inflexible curves may require initial casting.
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Growing rods for patients younger than 8–10 years with large progressive curves
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Definitive fusion for patients older than 10 years
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Anterior and posterior fusion often required
Review Infantile Idiopathic Scoliosis
Definition: idiopathic scoliosis that manifests before age 4 years
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Differences from adolescent idiopathic scoliosis
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Left thoracic curve most common
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More common in boys
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Plagiocephaly (skull flattening) often present
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Other congenital defects frequent
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Natural history
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Significant number of curves resolves spontaneously, up to 90% in one study.
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Risk for curve progression
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Phase of the ribs: position of the medial rib relative to the apical vertebra
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Phase I: no rib overlap
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Measure the rib-vertebra angle difference (RVAD) with Mehta classification
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Less than 20 degrees: low risk for progression (80% chance of no progression)
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More than 20 degrees: high risk for progression (80% chance of progression)
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Phase II: rib overlaps the apical vertebra
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Very high risk for curve progression
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Evaluation
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Clinical: examiner should look for plagiocephaly, perform complete neurologic examination, ask about developmental milestones.
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MRI: progressive infantile idiopathic scoliosis should be evaluated with MRI of the spinal cord. High incidence of neural axis abnormalities.
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Treatment
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Observation: curves less than 25 degrees with RVAD less than 20 degrees
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Bracing
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Used for modest and/or flexible deformity
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Milwaukee brace frequently used
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Mehta or derotational casting
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Indications: progressive deformity (progression of 10 degrees or past 25 degrees)
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Changed every 2–4 months
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Goals
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May be definitive treatment when initiated in very young patients
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May delay surgical treatment in other patients
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Surgery
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Distraction-based techniques
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Traditional growing rods, VEPTR (Vertical Expandable Prosthetic Titanium Rib), or magnetically controlled growing rods
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Serial lengthening every 4 to 6 months
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High rate of complications, both implant related and wound related
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Definitive fusion when patient is older than 10 years, if possible
Review congenital abnormalities in scoliosis
Review cogenital scoliosis
Congenital scoliosis
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Caused by a developmental defect in formation of the spine during fifth to eighth weeks of gestation
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High incidence of associated abnormalities
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Intraspinal: 20%–40%; obtain MRI
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Cardiac: 12%–26%
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Genitourinary: 20%
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Three basic types of defects (Fig. 3.27)
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Failure of segmentation (i.e., vertebral bar)
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Failure of formation (i.e., hemivertebrae)
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Mixed
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Risk for progression (Table 3.8)
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Depends on:
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Type of anomaly
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Remaining growth: worsens most rapidly during first 2 years of life and during adolescent growth spurt
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From most likely to progress to least likely:
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Unilateral bar with contralateral fully segmented hemivertebra(e): rapid and severe progression
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Unilateral bar: most common congenital deformity
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Multiple unilateral fully segmented hemivertebrae
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Single fully segmented hemivertebra
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Unsegmented or incarcerated hemivertebra (fused above and below)
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Block vertebrae: best prognosis
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Treatment
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Nonoperative
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Bracing generally ineffective
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May be useful for controlling compensatory curves and delaying surgery
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Operative
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Surgical options are varied and somewhat controversial.
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In situ spinal fusion
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Posterior in older patients or anterior/posterior spinal fusion in younger patients to avoid crankshaft phenomenon
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For smaller deformities with high likelihood of progression
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Convex hemiepiphysiodesis
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For smaller deformities with high likelihood of progression
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“Growth friendly” techniques
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Growing rods
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VEPTR
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Shilla technique
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Apical fusion with pedicle screws placed at proximal and distal extents of curve
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Rods slide along pedicle screws, promoting guided growth.
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Designed to allow thorax to continue to grow and delay definitive treatment
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Hemivertebra resection
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May be indicated for lumbosacral hemivertebrae associated with progressive curves and an oblique takeoff (severe truncal imbalance)
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Isolated hemivertebra excision should be accompanied by anterior/posterior arthrodesis with instrumentation to stabilize the adjacent vertebrae.
Review congenital kyphosis
Types
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Failure of formation (type I)
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Most common
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Worse prognosis
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Highest risk for neurologic complications
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When severe: immediate indication for surgery
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Failure of segmentation (type II)
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Mixed abnormalities (type III)
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Treatment
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Posterior fusion
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Favored in young children (<5 years) with curves of less than 50 degrees and normal findings on neurologic examination
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Functions as a posterior (convex) hemiepiphysiodesis
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Anterior/posterior fusion
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Reserved for older children or more severe curves
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Anterior vertebrectomy, spinal cord decompression, and anterior fusion followed by posterior fusion are indicated for curves associated with neurologic deficits.
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Vertebral column resection: hemivertebra causing coronal or sagittal plane deformity and/or large fixed spinal deformity
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A type II congenital kyphosis can be monitored to document progression, but progressive curves should be fused posteriorly.
Treatment overview for neuromuscular scoliois
Types
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Failure of formation (type I)
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Most common
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Worse prognosis
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Highest risk for neurologic complications
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When severe: immediate indication for surgery
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Failure of segmentation (type II)
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Mixed abnormalities (type III)
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Treatment
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Posterior fusion
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Favored in young children (<5 years) with curves of less than 50 degrees and normal findings on neurologic examination
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Functions as a posterior (convex) hemiepiphysiodesis
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Anterior/posterior fusion
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Reserved for older children or more severe curves
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Anterior vertebrectomy, spinal cord decompression, and anterior fusion followed by posterior fusion are indicated for curves associated with neurologic deficits.
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Vertebral column resection: hemivertebra causing coronal or sagittal plane deformity and/or large fixed spinal deformity
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A type II congenital kyphosis can be monitored to document progression, but progressive curves should be fused posteriorly.
Review neuromusular scoliosis
Typical underlying neuromuscular conditions associated with scoliosis
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Traumatic paralysis, Duchenne muscular dystrophy, Friedrich ataxia, spinal muscular atrophy, myelomeningocele, cerebral palsy, neurofibromatosis, arthrogryposis
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Curve characteristics
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Long, sweeping C-shaped curves
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Associated pelvic obliquity
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Can be rapidly progressive, especially for the patient in a wheelchair
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Associated characteristics
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Most affected patients have some pulmonary involvement secondary to the underlying condition (Duchenne muscular dystrophy) and detrimental contribution from the scoliosis.
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Cardiac issues common in Duchenne muscular dystrophy and other conditions
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Evaluation
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Pulmonary: bilevel positive airway pressure (BiPAP) may be required before and after surgery.
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Cardiac: for patients with Duchenne muscular dystrophy
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Nutritional laboratory markers
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Patients with WBC counts less than 1500 cells/μL and albumin levels lower than 3.5 g/dL have higher infection rates and longer hospital stays.
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Supplemental nutrition or gastrostomy tube feeding should be considered.
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Nonoperative treatment
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For the patient in a wheelchair, trunk support can be modified to provide better truncal balance.
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Use of corticosteroids in patients with Duchenne muscular dystrophy has been shown to reduce incidence and delay development of scoliosis.
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Brace
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Controversial and not typically used
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May be used to delay surgical treatment
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Surgical treatment
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Indications: vary with diagnosis and somewhat controversial
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Duchenne muscular dystrophy
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Surgery indicated when curve is progressive and more than 25–30 degrees in patients whose forced vital capacity (FVC) is greater than 40% of normal.
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Surgery is best tolerated before the patient’s FVC is less than 35% of age-matched normal values.
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Curve progression is rapid, and pulmonary and cardiac conditions worsen with time, precluding surgery.
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Cerebral palsy
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Ambulatory patients: surgery should be considered for a curve exceeding 50 degrees
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Nonambulatory patients: need for surgery depends on sitting balance and whether there are challenges with caring for the child. Curve magnitudes may be very large before surgical treatment.
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Fusion levels
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Nonambulatory patients
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Usually from T2 to pelvis
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Pelvic fixation with unit rods, Dunn-McCarthy rods, iliac bolts, or S2AI screws
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Segmental spinal fixation with wires or pedicle screws
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High complication rate
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Infection: up to 15% in one study; pelvic instrumentation a risk factor
