What is the next step in management for a patient with a unilateral facet dislocation at C4-C5 (cervical spine) after a motor vehicle collision?

Management of Unilateral Facet Dislocation at C4-C5

MRI of the cervical spine is the next step in management for this patient with a unilateral facet dislocation at C4-C5 following a motor vehicle collision.

Rationale for MRI

The patient has a confirmed unilateral facet dislocation at C4-C5 on CT scan, which represents a potentially unstable cervical spine injury. Before proceeding with definitive treatment, an MRI is essential to:

1. Assess for disc herniation or disruption of the disco-ligamentous complex that may complicate reduction 1
2. Evaluate for spinal cord compression or injury that may not be apparent on clinical examination
3. Guide the surgical approach (anterior vs. posterior) based on the pattern of injury 2

Management Algorithm for Unilateral Facet Dislocation

Step 1: Initial Assessment and Imaging

• CT scan has already confirmed unilateral facet dislocation at C4-C5
• Patient has midline cervical tenderness but intact neurological examination

Step 2: MRI Evaluation (Next Step)

• Assess for:
  • Disc herniation
  • Ligamentous injury
  • Spinal cord compression or signal changes
  • Facet fracture details

Step 3: Definitive Management

• Surgical fixation is indicated for unilateral facet dislocations as they represent unstable injuries according to the Subaxial Injury Classification (SLIC) System 1
• The SLIC system provides level I evidence with excellent reliability for guiding management of complex cervical fracture-dislocation injuries 1

Surgical Considerations

• Emergency surgical decompression should be performed within 24 hours of injury for optimal neurological outcomes 2
• Surgical approach (anterior vs. posterior) will be determined based on:
  • Presence of disc herniation (favors anterior approach)
  • Facet fracture pattern
  • Number of levels involved
  • Sagittal alignment 2

Important Caveats

• Do not attempt closed reduction before MRI: There is risk of neurological deterioration if disc herniation is present
• Avoid prolonged immobilization in cervical collar: Prolonged immobilization has significant attributable morbidity with complications appearing and rapidly escalating after 48-72 hours 1
• Rigid collars may not effectively restrict displacement of unstable cervical injuries and can paradoxically increase movement at the craniocervical and cervicothoracic junctions 1

Evidence-Based Outcomes

• Patients with unilateral facet dislocations left in the displaced position typically develop late pain as a complication 3
• Surgical reduction and fixation provides the best outcomes for unilateral facet dislocations 4, 5
• Anterior surgical approaches offer advantages of ease of access, low infection rates, and reduced risk of neurological worsening 4

The patient's intact neurological status is favorable for a good outcome, but prompt MRI followed by surgical fixation is essential to maintain spinal stability and prevent late complications.