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Introduction
  • Common cause of low back pain in children and adolescents. 
  • Conditions represent a continuum of disease including
    • pars stress reaction
    • spondylolysis
    • spondylolithesis
  • Definitions
    • pars stress reaction
      • sclerosis with incomplete bone disruption of pars
    • spondylolysis
      • term used to describe anatomic defect (radiolucent gap) in pars interarticularis with adjacent bone sclerosis
      • epidemiology
        • one of most common causes of back pain in children and adolescents
        • defects are not present at birth and develop over time (seen in 4-6% if population)
      • mechanism
        • usually activity related and occurs from repetitive hyperextension
        • prevalence as high as 47% in certain athletes (gymnasts, weightlifters, football linemen)
    • spondylolisthesis
      • defined as forward translation of one vertebral segment over the one beneath it
      • epidemiology
        • approximately 15% of individuals with a pars interarticularis lesion have progression to spondylolisthesis
        • most common at L5-S1 (90%) in adolescents and adults
      • risks of progression
        • the larger the slip the more likely it is to progress
        • dysplastic slips (Wiltse Type I) are more likely to progress
      • severity of current slip
        • correlates most strongly with pelvic incidence
Spondylolisthesis Classification
 
Wiltse-Newman Classification
Type I Dysplastic
• Secondary to congenital abnormalities of lumbosacral articulation including maloriented 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-Bartolozzi classification
 Developmental  • Includes Wiltse I and II
 Acquired  • Traumatic, postsurgical, pathologic, degenerative
 
Myerding Classification
 Grade I  • < 25%
 Grade II  • 25-50%
 Grade III  • 50-75%
 Grade IV  • 75-100%
 Grade V  • Spondyloptosis
 
Presentation
  • Symptoms
    • most cases of spondylolysis are asymptomatic
    • symptoms include insidious onset of activity related low back pain and/or buttock pain
    • neurologic symptoms include
      • hamstring tightness (most common) and knee contracture
      • radicular pain (L5 nerve root)
      • bowel and bladder symptoms
      • cauda equina syndrome (rare)
    • listhetic crisis
      • severe back pain aggravated by extension and relieved by rest
      • neurologic deficit
      • hamstring spasm - walk with a crouched gait
  • Physical exam
    • palpation and motion 
      • flattened lumbar lordosis 
      • palpable step off of spinous process
      • limitation of lumbar flexion and extension
        • pain with single-limb standing lumbar extension  
      • measure popliteal angle to evaluate for hamstring tightness 
    • neurologic exam
      • straight leg raise may be positive
      • rectal exam if bowel and bladder symptoms present
Imaging
  • Pars Stress Reaction & Spondylolysis
    • radiographs
      • lateral radiograph
        • may show defect in pars in 80% 
      • oblique radiograph
        • views may show sclerosis and elongation in pars interarticularis (scotty dog sign) 
      • AP
        • may see sclerosis of the stress reaction 
    • bone scan
      • most sensitive (however lesion may be cold) 
      • excellent screening tool for low back pain in children or adolescents
    • CT 
      • best study to diagnose and delineate anatomy of lesion 
      • pars stress reaction will show up as sclerosis on xrays and CT scan 
    • Single photon emission computer tomography (SPECT)  
      • best diagnostic adjunct when plain radiographs are negative  
  • Spondylolisthesis
    • radiograph
      • views
        • lateral xray 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  
        • 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 tilit =  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 enplate
          • 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 stenosis central and foraminal
NonOperative Treatment
  • Nonoperative
    • observation with no activity limitations
      • indications
        • asymptomatic patients with low-grade spondylolisthesis or spondylolysis 
      • may participate in contact sports 
    • physical therapy and 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 
        • watch low grade dysplastic carefully as there is a higher chance of progression
    • TLSO 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
      • outcomes
        • brace immobilization is superior to activity restriction alone for acute stress reaction  spondylolysis 
  • Operative
    • par interarticularis repair 
      • indications
        • L1 to L4 isthmic defect that has failed nonoperative management
        • multiple pars defects
    • L5-S1 in-situ posterolateral fusion with bone grafting
      • 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
    • L4-S1 posterolateral fusion, +/- reduction,  (+/- ALIF)
      • indications
        • high grade isthmic spondlylisthesis (Meyerding Grade III, IV, V) q
        • reduction is extremely controversial with no accepted guidelines 
Surgical Technique
  • 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
  • L5-S1 in-situ posterolateral fusion with bone grafting
    • approach
      • posterior midline approach to lumbar spine 
    • reduction
    • technique
      • in-situ fusion with bone grafting / with or without instrumentation 
      • postoperative immobilization in a TLSO
      • decompression only indicated if clinical symptoms of stenosis or radiculopathy
  • L4-S1 posterolateral fusion +/- reduction
    • approach
      • posterior midline approach to lumbar spine 
    • 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
      • usually instrumented
Complications
  • Neurologic deficits
  • Pseudoarthrosis
  • Progression of slippage
  • Hardware failure 
 

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