Pediatric Spondylolysis & Spondylolisthesis - Spine

Summary
- Pediatric Spondylolysis & Spondylolisthesis represent a continuum of disease where there is a fracture of the pars interarticularis (spondylolysis) which may progress to anterior subluxation of one vertebral body anterior to the adjacent inferior vertebral body (spondylolisthesis).
- Diagnosis of spondylolysis alone can be challenging on imaging and the ideal study is controversial. Radiographs, CT scan, and MRI may all play a role. Spondylolisthesis is diagnosed on a lateral radiograph.
- Treatment may be nonoperative or surgical depending on the degree of back pain, malalignment of vertebral bodies, and neurological symptoms.

Epidemiology
- Incidence
  - common
    
    up to 6-7% of adolescent athletes
    
    implicated in up to 47% of low back pain complaints in this population
- Demographics
  - higher incidence in Native Americans
- Anatomic location
  - typically involves pars of L5 and anterolisthesis of L5 relative to S1
- Risk factors
  - prevalence of spondylolysis may be as high as 47% in certain athletes (gymnasts, weightlifters, football linemen)
  - contact sports and those involving repetitive hyperextension (ex. linebacker)
  - higher sacral table index, pelvic incidence, sacral slope, and lower sacral table angle

Etiology
- Pathophysiology
  - conditions represent a continuum of disease including
    
    pars stress reaction
    
    defined as sclerosis of pars without complete bone disruption
    
    spondylolysis
    
    defined as a complete fracture of the pars interarticularis
    
    mechanism
    
    defects are not present at birth and develop over time (seen in 4-6% if population)
    
    usually activity related and occurs from repetitive hyperextension
    
    isthmic spondylolisthesis (spondylolytic spondylolithesis)
    
    defined as forward translation of one vertebral segment over the one beneath it due to a pars defect
    
    risks of progression
    
    approximately 15% of individuals with a pars interarticularis lesion have progression to spondylolisthesis
    
    the larger the slip the more likely it is to progress
    
    > Myerding 2 (>50% slip)
    
    dysplastic slips (Wiltse Type I) are more likely to progress
    
    severity of current slip
    
    correlates most strongly with pelvic incidence
    
    spondyloptosis
    
    100% translation of one vertebra over the next caudal vertebra
- Genetics
  - possible autosomal dominant inheritance pattern

                        Classification
                    
                        Wiltse-Newman Classification
                    
                        Type I
                    
                        Dysplastic
                    
                        Secondary to congenital abnormalities of lumbosacral articulation including mal-oriented or hypoplastic facets, sacral deficiency, poorly developed pars
                    
                        Posterior elements are intact (no spondylolysis)
                    
                        More significant neurologic symptoms
                    
                        Type II-A
                    
                        Isthmic - Pars Fatigue Fx
                    
                        Type II-B
                    
                        Isthmic - Pars Elongation due to healed stress fx
                    
                        Type II-C
                    
                        Isthmic - Pars Acute Fx
                    
                        Type III
                    
                        Degenerative
                    
                        Type IV
                    
                        Traumatic
                    
                        Type V
                    
                        Neoplastic
                    
                        Marchetti-BartolozziClassification
                    
                        Developmental
                    
                        Includes Wiltse I and II
                    
                        Acquired
                    
                        Traumatic, postsurgical, pathologic, degenerative
                    
                        Meyerding Classification
                    
                        Grade I
                    
                        < 25%
                    
                        Grade II
                    
                        25-50%
                    
                        Grade III
                    
                        50-75%
                    
                        Grade IV
                    
                        75-100%
                    
                        Grade V
                    
                        Spondyloptosis

Presentation
- History
  - classic history is healthy active adolescent who presents with acute onset of low back pain with athletic activity
- Symptoms
  - asymptomatic
    
    many cases of spondylolysis are asymptomatic
  - low back pain
    
    no association between radiologic grade and clinical presentation
    
    symptoms include insidious onset of activity related low back pain
  - leg symptoms
    
    buttock pain
    
    hamstring tightness (most common) and knee contracture
    
    radicular pain (L5 nerve root)
  - listhetic crisis
    
    severe back pain aggravated by extension and relieved by rest
    
    neurologic deficit
    
    hamstring spasm
  - bowel and bladder symptoms
    
    rare
  - cauda equina syndrome (rare)
- Physical exam
  - inspection
    
    high grade/dysplastic patients may develop "heart shaped buttocks" due to sacral prominence
    
    flattened lumbar lordosis
    
    palpation
    
    palpable step off of spinous process
  - motion
    
    limitation of lumbar flexion and extension
    
    measure popliteal angle to evaluate for hamstring tightness
  - neurovascular
    
    straight leg raise may be positive
    
    rectal exam if bowel and bladder symptoms present
  - provocative tests
    
    pain with single-limb standing lumbar extension
  - gait
    
    may walk with a crouched gait when symptoms severe

Imaging
- Pars stress reaction & spondylolysis
  - radiographs
    
    indications
    
    AP and lateral indicated in all patients with concern for spondylolysis and spondylolithesis
    
    AP view
    
    may see sclerosis of the stress reaction
    
    lateral view
    
    may show defect in pars in 80%
    
    oblique view
    
    views may show sclerosis and elongation in pars interarticularis (scotty dog sign)
    
    some studies have shown that oblique does not provide more diagnostic information than AP and lateral radiographs but does increase radiation exposure
  - CT
    
    inidcations
    
    best study to delineate anatomy of lesion
    
    findings
    
    pars stress reaction will show up as sclerosis on x-rays and CT scan
  - single photon emission computer tomography (SPECT)
    
    indications
    
    previously considered the best diagnostic adjunct when plain radiographs are negative; however, now rarely performed given unnecessary radiation exposure
    
    can also detect osteoid osteomas, sacroiliitis, osteitis pubis, and disc herniation
    
    techniques
    
    combines technique of bone scan with CT in order to help localize an area of abnormal activity seen on bone scan
  - MRI
    
    indications
    
    negative ragdiographs with high suspicion
    
    very acute presentation
    
    any neurological deficits
    
    sensitivity & specificity
    
    recent studies have shown MRI to be as sensitive and specific as SPECT, with the additional benefit of avoiding radiation exposure
  - bone scan
    
    indications
    
    excellent screening tool for low back pain in children or adolescents
    
    sensitivity & specificity
    
    most sensitive (however lesion may be cold)
- Spondylolisthesis
  - radiographs
    
    views
    
    lateral x-ray used to measure slip angle and grade.
    
    flexion and extension radiographs used to evaluate instability
    
    measurements
    
    slip grade
    
    slippage on plain lateral radiographic imaging measured in accordance to the vertebra below
    
    the caudal vertebra is divided into four parts
    
    Grade I means a translation of the cranial vertebra of up to 25%
    
    Grade II of up to 50%
    
    Grade III of up to 75%
    
    Grade IV up to 100%
    
    Grade V describes the ptosis of the cranial vertebra
    
    slip angles
    
    methodology to determine slip angle
    
    most important determinant for nonunion and pain
    
    angle >45-50 degrees associated with greater slip progression, instability, and development of post-op pseudo
    
    pelvic incidence
    
    pelvic incidence = pelvic tilt + sacral slope
    
    a line is drawn from the center of the S1 endplate to the center of the femoral head
    
    a second line is drawn perpendicular to a line drawn along the S1 endplate, intersecting the point in the center of the S1 endplate
    
    the angle between these two lines is the pelvic incidence (see angle X in figure above)
    
    correlates with severity of disease
    
    pelvic incidence has direct correlation with the Meyerding–Newman grade
    
    pelvic tilt
    
    pelvic tilt = pelvic incidence - sacral slope
    
    a line is drawn from the center of the S1 endplate to the center of the femoral head
    
    a second vertical line (parallel with side margin of radiograph) line is drawn intersecting the center of the femoral head
    
    the angle between these two lines is the pelvic tilt (see angle Z in figure above)
    
    sacral slope
    
    sacral slope = pelvic incidence - pelvic tilt
    
    a line is drawn parallel to the S1 endplate
    
    a second horizontal line (parallel to the inferior margin of the radiograph) is drawn
    
    the angle between these two lines is the sacral slope (see angle Y in the figure above)
  - CT
    
    best study to diagnose and delineate anatomy of pars defect
  - MRI
    
    indicated if neurologic symptoms present
    
    useful to diagnose associated central and foraminal stenosis

Treatment
- Nonoperative
  - observation alone (no activity limitations)
    
    indications
    
    asymptomatic patients
    
    regardless of slip grade which does not correlate with clinical presentation
    
    return to in contact sports is controvesial
    
    limited evidence to guide surgeons following surgical management, decision must be individualized
    
    some data shows patients who stop sports for at least 3 months have improved outcomes compared to those who continue to play
    
    outcomes
    
    typically do well and remain asymptomatic
  - physical therapy & activity restriction
    
    indications
    
    symptomatic isthmic spondylolysis
    
    symptomatic low-grade spondylolisthesis
    
    technique
    
    physical therapy should be done for 6 months and include
    
    hamstring stretching
    
    pelvic tilts
    
    abdominal strengthening
    
    outcomes
    
    most improve and do not require surgery
    
    watch low grade dysplastic carefully as there is a higher chance of progression
  - bracing for 6 to 12 weeks
    
    indications
    
    acute pars stress reaction spondylolysis
    
    isthmic spondylolysis that has failed to improve with physical therapy
    
    low grade spondylolisthesis that has failed to improve with physical therapy
    
    technique
    
    typically a TLSO
    
    outcomes
    
    brace immobilization is superior to activity restriction alone for acute stress reaction spondylolysis
- Operative
  - pars interarticularis repair
    
    indications
    
    L1 to L4 isthmic defect that has failed nonoperative management
    
    multiple pars defects
    
    outcomes
    
    typically superior to fusion procedures, preserves motion
  - L5-S1 posterolateral fusion, +/- ALIF, +/- sacroiliac fusion
    
    indications
    
    L5 spondylolysis that has failed nonoperative treatment
    
    low grade spondylolisthesis (Myerding Grade I and II) that
    
    has failed nonoperative treatment
    
    is progressive
    
    has neurologic deficits
    
    is dysplastic due to high propensity for progression
    
    return to sport
    
    some evidence to support that ALIF may help return to competetitive sports
    
    most surgeons allow return to noncontact sports 3-6 months following fusion and return to contact sports 6-12 months (controversial)
    
    outcomes
    
    patients typically do well and return to sport in 3-6 months
  - L4-S1 posterolateral fusion, +/- reduction, +/- sacroiliac fusion, +/- ALIF
    
    indications
    
    high grade spondylolytic spondlylisthesis (Meyerding Grade III, IV, V)
    
    reduction is extremely controversial with no accepted guidelines
    
    outcomes
    
    patients typically do well but may have greater motion limitations with multi-level fusion
    
    over-aggressive reduction techniques may result in neurologic impairments

Techniques
- Par interarticularis repair
  - approach
    
    posterior midline approach to lumbar spine
  - technique
    
    repair pars defect with screw fixation, tension wiring, or screw and sublaminar hook technique
    
    decompression indicated if clinical symptoms of stenosis
    
    contraindications
    
    disc degeneration (obtain MRI for sx planning)
- L5-S1 posterolateral fusion +/- ALIF
  - approach
    
    posterior midline approach to lumbar spine
  - technique
    
    decompression only indicated if clinical symptoms of stenosis or radiculopathy
    
    in-situ fusion with bone grafting / with or without instrumentation
  - postoperative
    
    usually postoperative immobilization in a TLSO
- L4-S1 posterolateral fusion, +/- reduction, +/- sacroiliac fusion, +/- ALIF
  - approach
    
    posterior midline approach to lumbar spine
  - technique
    
    reduction
    
    reduction may be done with instrumentation or positioning
    
    pros of reduction
    
    can restore sagittal alignment and reduce lumbosacral kyphosis
    
    cons
    
    risk of significant complications (8-30%) including
    
    L5 is the most common nerve root injury with reduction
    
    sexual dysfunction
    
    catastrophic neurologic injury
    
    fusion/decompression
    
    usually instrumented
    
    the addition of decompression and anterior-posterior (360 deg) fusion is associated with more in-hospital complications
    
    the use of interbody cages in this population has decreased significantly, while costs associated with treatment in general have increased over time

Complications
- Neurologic deficits
  - consider neuromonitoring during reduction, especially in a high-grade slip
  - L5 n. root injury is the most common neuro cx
- Pseudoarthrosis
- Slip Progression
- Hardware failure

Prognosis
- Most symptomatic patients can be successfully managed nonoperatively
- In patients who fail non-operative management, spinal fusion results in 90% success rates
- Return to sports is controversial

Action	Numeric Key	Letter Key	Function Key
Show Bullets		S	Enter (frontside only)
20%	1	N
40%	2	H
60%	3	F	Enter (backside only)
80%	4	E
100%	5	M
Toss	0	T

Wiltse-Newman Classification
Type I	Dysplastic Secondary to congenital abnormalities of lumbosacral articulation including mal-oriented or hypoplastic facets, sacral deficiency, poorly developed pars Posterior elements are intact (no spondylolysis) More significant neurologic symptoms
Type II-A	Isthmic - Pars Fatigue Fx
Type II-B	Isthmic - Pars Elongation due to healed stress fx
Type II-C	Isthmic - Pars Acute Fx
Type III	Degenerative
Type IV	Traumatic
Type V	Neoplastic

Marchetti-BartolozziClassification
Developmental	Includes Wiltse I and II
Acquired	Traumatic, postsurgical, pathologic, degenerative

Meyerding Classification
Grade I	< 25%
Grade II	25-50%
Grade III	50-75%
Grade IV	75-100%
Grade V	Spondyloptosis