Pediatric Spondylolysis

  • Etiology:
    — Stress fracture from repetitive microtrauma of posterior vertebral elements at pars interarticularis which is weakest part of vertebral body
    — Associated with hyperextension sports – gymnastics or diving or weight lifting or football or soccer or hockey or lacrosse
  • Imaging Radiograph:
    — Early: Sclerosis
    — Later: Lucent pars interarticularis defect = Scotty dog sign
    — Contralateral pedicle often sclerotic due to stress = Wilkinson’s syndrome
  • Imaging Bone scan:
    — Needs to be done with SPECT for highest sensitivity
    — Increased uptake
  • Imaging CT: Incomplete ring sign with pars defect noted 10-15 millimeters above disc space
  • DDX:
  • Complications:
  • Treatment:
  • Clinical:
    — Unilateral or bilateral (75%)
    — Most common at L5-S1
    — Incidence is 5% of general population
    — Usually asymptomatic

Radiology Cases of Spondylolysis

Radiograph and bone scan of spondylosis
Lateral radiograph of the lumbar spine shows a lucency through the pars interarticularis of the L5 vertebral body (pars defect). Axial and coronal images from a nuclear medicine bone scan show increased radiotracer localization in the right L5 pars interarticularis.
Bone scan of spondylolysis
Planar images from a bone scan viewed posteriorly (above left and above middle) and anteriorly (above right) show focal uptake in the pars interarticularis of the L5 vertebral body bilaterally, left greater than right. This is better demonstrated on the axial, sagittal and coronal tomographic images (below).