Spondylolisthesis (Paediatrics / Spine)

Epidemiology:

• Affects 5% of the population.
• More common in males, but females often experience more severe cases.
• Increased incidence among Eskimos.

Aetiology:

• 25% of individuals with spondylolysis (pars defect) develop spondylolisthesis.
• Most common at L5/S1, followed by L4/5, then L3/4.
• Typically an acquired condition.

Classification:

Type (Wiltse):

1. Dysplastic:
   • Facet joint anomaly with an intact posterior neural arch.
2. Isthmic:
   • 2a: Stress fracture of pars (spondylolysis).
   • 2b: Elongated pars (most common).
   • 2c: Acute fracture of pars (rare).
3. Other types:
   • Degenerative, post-traumatic, pathologic, iatrogenic (less common in children).

Grade (Myerding 1-5):

• Grade 1: 0-25% slip.
• Grade 2: 25-50% slip.
• Grade 3: 50-75% slip.
• Grade 4: 75-100% slip.
• Grade 5: >100% (spondyloptosis).

Clinical Features:

• Activity-related low back pain, exacerbated by extension activities.
• Visible deformity.
• Tight hamstrings.
• L5 nerve root impingement.

Imaging:

• Standing AP, Lateral, Oblique X-rays.
• Scotty dog sign visible on oblique views.
• CT scan is more effective than MRI.
• Bone scan or SPECT scan may be used.

Risk of Progression:

• High grade (3-4).
• Dysplastic spondylolisthesis.
• Females are at higher risk.
• >40 degrees of lumbosacral kyphosis.
• Progression is more likely pre-growth spurt.

Management:

Non-Operative:

• Low grade asymptomatic: Observation.
• Low grade symptomatic: Brace for 6 months.

Operative Indications:

• High grade slip.
• Evidence of progression to high grade.
• Intractable pain.
• Risk factors for progression:
  • Dysplastic spondylolisthesis (higher neurologic risk).
  • Intact posterior arch increases risk of neurologic injury if slip progresses.

Surgical Technique:

• Posterolateral in situ instrumented fusion.
• Concurrent decompression if there is neurologic compromise.
• Reduction may be considered for high-grade slips but can increase the risk of L5 traction injury.

Complications:

• Neurologic injury/cauda equina (rare).
• Slip progression.
• Pseudoarthrosis.
• Continued pain.
• Adjacent level degeneration.