Atlantoaxial Rotary Fixation

Aka: Atlantoaxial Rotary Fixation

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II. Epidemiology

  1. Primarily occurs in children with risk factors (see below)
  2. May also occur in adults

III. Pathophysiology

  1. Minor Trauma or inflammation from mild Upper Respiratory Infection results in Cervical Ligamentous Instability
  2. Atlantoaxial joint becomes unstable, allowing for subluxation C1 on C2

IV. Risk Factors

  1. See Atlantoaxial Instability
  2. Juvenile Rheumatoid Arthritis
  3. Down Syndrome
  4. Marfan Syndrome
  5. Osteogenesis imperfecta
  6. Rickets
  7. Ehlers-Danlos

V. Signs

  1. Patient cannot assume a neutral head and neck position
  2. Head in cock-robin position
    1. Head with lateral flexion to one side
    2. Neck rotated to the opposite side
    3. Neck slightly flexed

VI. Imaging

  1. CT Cervical Spine (preferred)
    1. First-line study (replaces XRay)
    2. Dynamic CT is preferred
      1. When subluxed, C1 and C2 will rotate together in tandem
      2. First CT with head facing forward
      3. Next CT with head and neck maximally rotated right
      4. Next CT with head and neck maximally rotated left
  2. XRay Cervical Spine
    1. Indicated where CT is not available

VII. Classification

  1. Class 1
    1. Unilateral facet subluxation <3 mm
    2. No anterior displacement
    3. Intact transverse ligament
  2. Class 2
    1. Unilateral facet subluxation 3-5 mm
    2. Injury to transverse ligament may be present
  3. Class 3
    1. Bilateral facet subluxation >5 mm
    2. Risk of neurologic injury and sudden death (uncommon)
  4. Class 4
    1. Posterior displacement of axis
    2. Risk of neurologic injury and sudden death (uncommon)

VIII. Management

  1. Consult pediatric orthopedics or Spine Surgery
  2. Class 1 and 2 with early presentation (within 1 week)
    1. Conservative therapy (Analgesics, soft collar)
    2. Often reduces spontaneously once inflammation subsides
    3. May be observed outpatient with close follow-up in most cases
  3. Class 3 to 4 OR delayed presentation 1 to 4 weeks
    1. Admit to hospital on Analgesics and Muscle relaxants
    2. Halter traction (via chin and head straps)
    3. Consider manipulation under Anesthesia (OR) in refractory cases (not reducing on Halter traction)
      1. Manipulation under fluoroscopy
      2. Long traction (halo device) for 3 months after reduction
  4. Refractory cases (esp. late presentations >4 weeks)
    1. May try methods as above
    2. May require C1-2 fusion in refractory cases

IX. Prognosis

  1. Best prognosis with Class 1-2 and with early presentation (within 1 week)

X. References

  1. Jhun, Grock, Ebenezer in Herbert (2016) EM:Rap 16(7): 11-3

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