What is congenital spondylolysis spondylolisthesis?

Congenital Spondylolysis and Spondylolisthesis

Congenital spondylolysis spondylolisthesis is a spinal condition characterized by a defect or fracture in the pars interarticularis (spondylolysis) that can lead to forward slippage of a vertebra over the one beneath it (spondylolisthesis), resulting from a growth disturbance of lumbosacral vertebrae influenced by genetic and environmental factors.

Pathophysiology

• Spondylolysis refers to a defect or elongation in the pars interarticularis of the lumbar spine, which can be unilateral or bilateral 1
• The etiology is considered a stress fracture due to repetitive loading associated with genetic predisposition 1
• Spondylolisthesis occurs when there is forward translation of one vertebral segment over the one beneath it, often developing in growing children with bilateral spondylolysis 1, 2
• The condition creates neuroforaminal stenosis through:
  • Direct foraminal narrowing reducing space for nerve roots 3
  • Abnormal loading on facet joints causing hypertrophy 3
  • Buckling of ligamentum flavum contributing to neural compression 3

Clinical Presentation

• Many cases are asymptomatic, but symptomatic cases can be very disabling 2
• Typical presentation includes:
  • Activity-related low back pain
  • Painful spinal mobility
  • Hamstring tightness
  • Radiculopathy (in cases with significant nerve compression) 4
  • Neurogenic claudication and motor/sensory deficits in affected nerve root distribution 3

Diagnostic Imaging

• Plain radiographs: Initial assessment to identify defects and measure degree of slippage
• MRI: Shows increased signal intensity before an actual fracture line develops 1
• CT scans: Better visualization of bony defects
• Flexion-extension radiographs: Demonstrate dynamic changes in foraminal dimensions and potential instability 3
• Single-photon emission computed tomography (SPECT): Useful for establishing early diagnosis 4

Classification and Natural History

• Low-grade spondylolisthesis: ≤50% translation of vertebra
• High-grade spondylolisthesis: >50% translation of vertebra 4
• Progression risk factors:
  • Young age
  • Vertical sacrum (lumbosacral angle <100 degrees) 5
  • Bilateral pars defects
• Two-thirds of children with acute spondylolysis will achieve bony union with early activity restriction 1
• One-fourth of patients with non-union will develop spondylolisthesis 1

Management

Non-surgical Treatment

• Indicated for:
  • Symptomatic stress reactions of pars interarticularis
  • Spondylolysis
  • Low-grade spondylolisthesis (≤50% translation)
• Approaches include:
  • Activity restriction
  • Immobilization (bracing)
  • Physiotherapy 4
  • Low-intensity pulsed ultrasound (LIPUS) shows promise for achieving higher rates of bony union 6

Surgical Treatment

• Indicated when:

  • Pain persists despite 6 months of conservative treatment
  • Progressive vertebral displacement
  • Neurologic deficits
  • High-grade spondylolisthesis (>50% translation) 1, 4

• Surgical options:

  • Isthmic repair (for very specific cases)
  • Posterolateral fusion (PLF) - most common approach
  • Instrumented fusion to prevent slip progression in young patients
  • Reduction and fusion for severe cases 2

Prognosis

• Health-related quality of life is improved in patients achieving bony union compared to those with non-union 1
• Most cases of low-grade spondylolisthesis with horizontal sacrum show little progression 5
• Spondylolisthesis with vertical sacrum (lumbosacral angle <100 degrees) is typically progressive and may require surgical intervention 5

Common Pitfalls and Caveats

• Avoid diagnosing mechanical back pain without appropriate imaging in children and adolescents with persistent symptoms
• Dysplastic spondylolisthesis with intact posterior elements requires greater caution in management 4
• Excision of the loose arch alone should not be performed, especially in young patients 2
• Growing children need to be followed clinically and radiographically through skeletal maturity 4
• Surgical fusion without instrumentation may lead to pseudarthrosis and slip progression in young patients 7