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Flashcards in Miller-Pediatric Spine Deck (15)
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1

Review important markers for Idiopathic Adolesent Scoliois

2

Know the indications to order an MRI with AIS

MRI indications:

Left thoracic curves

Painful or rapidly progressing scoliosis

Apical kyphosis of the thoracic curve

Juvenile-onset scoliosis (onset before age 10 years)

Neurologic signs or symptoms

Congenital abnormalities

3

Review Peak Height Velocity

4

General Overview for AIS

Onset after 10 years of age

Likely multifactorial cause

May be related to a hormonal, brainstem, or proprioception disorder

Most patients have a positive family history but variable expression.

Diagnosis

School screening mandated by several states

Rotational deformities noted on the Adams forward bend test (assessed with scoliometer)

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.

Shoulder elevation, waistline asymmetry, trunk shift, LLD, rib rotational deformity (rib hump), and prominent scapula

Neurologic findings should be normal.

Abnormal findings, especially asymmetric abdominal reflexes, should prompt an MRI study.

Cavus feet should also prompt MRI to assess for intraspinal abnormalities.

Imaging studies

Standing full-length posteroanterior radiograph

Cobb method used to measure magnitude of curves (Fig. 3.24)

Assessment for Risser sign (ossification of the iliac crest apophysis)

Stable vertebra: most proximal vertebra that is the most closely bisected by the center sacral vertical line (CSVL)

End vertebrae: the most tilted vertebrae

Neutral vertebra: the vertebra that has no rotation in the axial plane

Lateral radiograph

Hypokyphosis of thoracic spine and hypolordosis of lumbar spine typically seen

If hyperkyphosis of the thoracic spine is observed, MRI should be considered.

Spondylolisthesis at the level of L5–S1 should be sought.

MRI indications:

Left thoracic curves

Painful or rapidly progressing scoliosis

Apical kyphosis of the thoracic curve

Juvenile-onset scoliosis (onset before age 10 years)

Neurologic signs or symptoms

Congenital abnormalities

5

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.

Curves greater than 20 degrees in very young patients

Thoracic curves greater than 45–50 degrees at skeletal maturity are likely to progress during adulthood.

Lumbar curves may progress at a lower threshold.

Peak height velocity (PHV) (Fig. 3.26)

Best predictor for progression

Occurs during Risser stage 0, which makes the Risser sign less useful

Occurs before menarche

Closure of the olecranon apophysis correlates with PHV

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.

6

Review the treatment options for AIS

Treatment

Depends on the likelihood of curve progression

Observation

1. Skeletally immature patients with curves less than 20–25 degrees

2. 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.

Indications: curves of more than 25 degrees or of 20 degrees with documented progression

Types of braces:

 

Milwaukee brace (cervicothoracolumbosacral orthosis [CTLSO]); rarely used

Boston underarm thoracolumbosacral (TLSO) orthosis

For curves with the apex at T8 or below

Thoracic lordosis or hypokyphosis is a relative contraindication.

Bracing has been shown to be less effective in boys and overweight patients.

Some writers recommend 18 hours/day in patients at Risser stage 0.

Effectiveness of bracing in patients with idiopathic scoliosis is “dose dependent”; 90% effective when worn more than 12–13 hours/day

Surgery

Goals

Prevent curve progression and obtain solid fusion

Obtain and maintain correction in the coronal, axial, and sagittal planes while avoiding complications

Posterior instrumentation and fusion

Segmental instrumentation with pedicle screws (most common), hooks, or wires connected to rods

Pullout strength increased by using larger screws and longer screws, tapping 1 mm less than screw diameter, and using “straightforward” insertion technique

Correction of deformity and arthrodesis (fusion)

Anterior instrumentation and fusion

Uncommon as single approach but useful in two cases:

Single thoracic fusion, especially if hypokyphosis is present and if fusion levels can be saved

Single thoracolumbar/lumbar fusion

Indications for use in combination with posterior approach:

Very young patients: triradiate cartilage open; used to prevent crankshaft phenomenon

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.

Fusion levels

Determining levels is complex and based on many factors.

Main goal: to minimize the number of fusion levels while achieving good coronal and sagittal balance

Generally the fusion should:

Include structural curves

Include nonstructural lumbar curves that are:

Greater than 45 degrees

Associated with significant rotation or translation

Fusion to T2 proximally when:

Left shoulder is elevated

T1 tilt is greater than 5 degrees

Proximal thoracic curve has significant rotation

For Lenke 1 and 2 curves:

A modifier: fusion distally to vertebra touched by CSVL unless L4 is tilted to the right (fuse one or two levels distally)

B modifier: fusion distally to stable vertebra

Lenke 3 through 6 curves:

Fusion to distal end vertebra

7

Review the surgical complications with AIS

Infection (1.2%–1.3%)

Acute

S. aureus most common

Irrigation and débridement and antibiotic suppression usually required until fusion if infection is deep

Delayed

Slow-growing organisms: Propionibacterium acnes, Staphylococcus epidermidis

Treatment: removal of implants, check for pseudarthrosis, antibiotics

Pseudarthrosis: (1%–3%)

Manifests with pain, fractured rod

Difficult to visualize with imaging studies

Treatment: compression instrumentation bone grafting

Neurologic deficits (0.5%–0.7%)

Usually nerve root or incomplete spinal cord injury

Implant related: instrumentation placed in canal or foramen

Blood vessel–related: during correction

Intraoperative spinal cord monitoring is crucial.

If changes occur intraoperatively, the surgical team should check leads, raise blood pressure, transfuse, reverse steps of surgery, and reassess.

If neurologic responses are still diminished, implants should be completely removed.

Crankshaft phenomenon

Continued anterior spinal growth after posterior fusion in skeletally immature patients

Increased rotation and deformity of the spine

Can be avoided by anterior discectomy and fusion coupled with posterior spinal fusion

8

General review of Early Onset Scoliosis

The Scoliosis Research Society defines early-onset scoliosis (EOS) as scoliosis diagnosed before age 10 years.

Comprises a heterogeneous group, including congenital scoliosis and infantile and juvenile idiopathic scoliosis; see individual sections for treatment options.

Thoracic insufficiency syndrome

Inability of the thorax to support normal respiration or lung growth

Causes

Severe congenital scoliosis with rib fusions

Jarcho-Levin syndrome: extensive vertebral and rib fusions

Jeune syndrome or asphyxiating thoracic dystrophy: rib dysplasia causing a shortened and narrow thorax

Diagnosis

Clinical signs of respiratory insufficiency

Loss of chest wall mobility as demonstrated by the thumb excursion test

Worsening indices of three-dimensional thoracic deformity

Radiographic studies: measurement of T1–12 height

CT scans: lung volumes

Pulmonary function tests: Relative decline in percentage of predicted vital capacity

9

Define Juvenile Idiopathic Scoliosis

Definition: idiopathic scoliosis that manifests between 4 and 10 years of age

Presentation: similar to that of adolescent scoliosis in terms of manifestations and treatment

Right thoracic curve most common

Differences from adolescent idiopathic scoliosis

Higher risk of progression, up to 95% in one study

Less likely to respond to bracing

More likely to require surgical treatment

Rate of spinal cord abnormality: 25%

MRI should routinely be obtained.

Treatment

Observation: curves less than 25 degrees

Nonoperative treatment: curves between 25 and 45 degrees

Bracing

Stiff, inflexible curves may require initial casting.

Growing rods for patients younger than 8–10 years with large progressive curves

Definitive fusion for patients older than 10 years

Anterior and posterior fusion often required

10

Review Infantile Idiopathic Scoliosis

Definition: idiopathic scoliosis that manifests before age 4 years

Differences from adolescent idiopathic scoliosis

Left thoracic curve most common

More common in boys

Plagiocephaly (skull flattening) often present

Other congenital defects frequent

Natural history

Significant number of curves resolves spontaneously, up to 90% in one study.

Risk for curve progression

Phase of the ribs: position of the medial rib relative to the apical vertebra

Phase I: no rib overlap

Measure the rib-vertebra angle difference (RVAD) with Mehta classification

Less than 20 degrees: low risk for progression (80% chance of no progression)

More than 20 degrees: high risk for progression (80% chance of progression)

Phase II: rib overlaps the apical vertebra

Very high risk for curve progression

Evaluation

Clinical: examiner should look for plagiocephaly, perform complete neurologic examination, ask about developmental milestones.

MRI: progressive infantile idiopathic scoliosis should be evaluated with MRI of the spinal cord. High incidence of neural axis abnormalities.

Treatment

Observation: curves less than 25 degrees with RVAD less than 20 degrees

Bracing

Used for modest and/or flexible deformity

Milwaukee brace frequently used

Mehta or derotational casting

Indications: progressive deformity (progression of 10 degrees or past 25 degrees)

Changed every 2–4 months

Goals

May be definitive treatment when initiated in very young patients

May delay surgical treatment in other patients

Surgery

Distraction-based techniques

Traditional growing rods, VEPTR (Vertical Expandable Prosthetic Titanium Rib), or magnetically controlled growing rods

Serial lengthening every 4 to 6 months

High rate of complications, both implant related and wound related

Definitive fusion when patient is older than 10 years, if possible

11

Review congenital abnormalities in scoliosis

12

Review cogenital scoliosis

Congenital scoliosis

Caused by a developmental defect in formation of the spine during fifth to eighth weeks of gestation

High incidence of associated abnormalities

Intraspinal: 20%–40%; obtain MRI

Cardiac: 12%–26%

Genitourinary: 20%

Three basic types of defects (Fig. 3.27)

Failure of segmentation (i.e., vertebral bar)

Failure of formation (i.e., hemivertebrae)

Mixed

Risk for progression (Table 3.8)

 

Depends on:

Type of anomaly

Remaining growth: worsens most rapidly during first 2 years of life and during adolescent growth spurt

From most likely to progress to least likely:

Unilateral bar with contralateral fully segmented hemivertebra(e): rapid and severe progression

Unilateral bar: most common congenital deformity

Multiple unilateral fully segmented hemivertebrae

Single fully segmented hemivertebra

Unsegmented or incarcerated hemivertebra (fused above and below)

Block vertebrae: best prognosis

Treatment

Nonoperative

Bracing generally ineffective

May be useful for controlling compensatory curves and delaying surgery

Operative

Surgical options are varied and somewhat controversial.

In situ spinal fusion

Posterior in older patients or anterior/posterior spinal fusion in younger patients to avoid crankshaft phenomenon

For smaller deformities with high likelihood of progression

Convex hemiepiphysiodesis

For smaller deformities with high likelihood of progression

“Growth friendly” techniques

Growing rods

VEPTR

Shilla technique

Apical fusion with pedicle screws placed at proximal and distal extents of curve

Rods slide along pedicle screws, promoting guided growth.

Designed to allow thorax to continue to grow and delay definitive treatment

Hemivertebra resection

May be indicated for lumbosacral hemivertebrae associated with progressive curves and an oblique takeoff (severe truncal imbalance)

Isolated hemivertebra excision should be accompanied by anterior/posterior arthrodesis with instrumentation to stabilize the adjacent vertebrae.

13

Review congenital kyphosis

Types

Failure of formation (type I)

Most common

Worse prognosis

Highest risk for neurologic complications

When severe: immediate indication for surgery

Failure of segmentation (type II)

Mixed abnormalities (type III)

Treatment

Posterior fusion

Favored in young children (<5 years) with curves of less than 50 degrees and normal findings on neurologic examination

Functions as a posterior (convex) hemiepiphysiodesis

Anterior/posterior fusion

Reserved for older children or more severe curves

Anterior vertebrectomy, spinal cord decompression, and anterior fusion followed by posterior fusion are indicated for curves associated with neurologic deficits.

Vertebral column resection: hemivertebra causing coronal or sagittal plane deformity and/or large fixed spinal deformity

A type II congenital kyphosis can be monitored to document progression, but progressive curves should be fused posteriorly.

14

Treatment overview for neuromuscular scoliois

Types

Failure of formation (type I)

Most common

Worse prognosis

Highest risk for neurologic complications

When severe: immediate indication for surgery

Failure of segmentation (type II)

Mixed abnormalities (type III)

Treatment

Posterior fusion

Favored in young children (<5 years) with curves of less than 50 degrees and normal findings on neurologic examination

Functions as a posterior (convex) hemiepiphysiodesis

Anterior/posterior fusion

Reserved for older children or more severe curves

Anterior vertebrectomy, spinal cord decompression, and anterior fusion followed by posterior fusion are indicated for curves associated with neurologic deficits.

Vertebral column resection: hemivertebra causing coronal or sagittal plane deformity and/or large fixed spinal deformity

A type II congenital kyphosis can be monitored to document progression, but progressive curves should be fused posteriorly.

15

Review neuromusular scoliosis

Typical underlying neuromuscular conditions associated with scoliosis

Traumatic paralysis, Duchenne muscular dystrophy, Friedrich ataxia, spinal muscular atrophy, myelomeningocele, cerebral palsy, neurofibromatosis, arthrogryposis

Curve characteristics

Long, sweeping C-shaped curves

Associated pelvic obliquity

Can be rapidly progressive, especially for the patient in a wheelchair

Associated characteristics

Most affected patients have some pulmonary involvement secondary to the underlying condition (Duchenne muscular dystrophy) and detrimental contribution from the scoliosis.

Cardiac issues common in Duchenne muscular dystrophy and other conditions

Evaluation

Pulmonary: bilevel positive airway pressure (BiPAP) may be required before and after surgery.

Cardiac: for patients with Duchenne muscular dystrophy

Nutritional laboratory markers

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.

Supplemental nutrition or gastrostomy tube feeding should be considered.

Nonoperative treatment

For the patient in a wheelchair, trunk support can be modified to provide better truncal balance.

Use of corticosteroids in patients with Duchenne muscular dystrophy has been shown to reduce incidence and delay development of scoliosis.

Brace

Controversial and not typically used

May be used to delay surgical treatment

Surgical treatment

Indications: vary with diagnosis and somewhat controversial

Duchenne muscular dystrophy

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.

Surgery is best tolerated before the patient’s FVC is less than 35% of age-matched normal values.

Curve progression is rapid, and pulmonary and cardiac conditions worsen with time, precluding surgery.

Cerebral palsy

Ambulatory patients: surgery should be considered for a curve exceeding 50 degrees

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.

Fusion levels

Nonambulatory patients

Usually from T2 to pelvis

Pelvic fixation with unit rods, Dunn-McCarthy rods, iliac bolts, or S2AI screws

Segmental spinal fixation with wires or pedicle screws

High complication rate

Infection: up to 15% in one study; pelvic instrumentation a risk factor