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Introduction
  • Occipital condyle fractures are traumatic injuries that involve the craniocervicaljunction (CCJ) 
  • Epidemiology
    • incidence
      • approximately 1-3% of population with blunt craniocervical trauma
      • often missed due to low diagnosis sensitivity of plain radiographs 
      • increased rate of diagnosis use due to increase in CT scan use 
  • Pathophysiology
    • mechanism of injury
      • high energy, non-penetrating trauma to the head/neck
      • fracture patterns are dependent on the directional forces applied to the craniocervical junction
        • Anderson and Montesano classification 
          • Type 1 = compression 
          • Type 2 = direct blow  
          • Type 3 = rotational/lateral bending 
  • Associated injuries
    • orthopaedic manifestations
      • cervical spinal cord injuries (31%)
      • polytrauma
    • medical manifestations
      • intracranial bleeding
      • brainstem and vascular lesions
      • elevated ICP
  • Prognosis
    • High mortality rate (11%) due to associated injuries
Anatomy
  • Osteology
    • occipital condyles are paired prominences of the occipital bone
    • oval or bean shaped structures forming lateral aspects of the foramen magnum
  • Joint articulations
    • intrinsic relationship between occiput, atlas and axis to form the occipitoatlantoaxial complex or CCJ
    • 6 main synovial articulations
      • anterior and posterior median atlanto-odontoid joints
      • paired occipitoatloid joints
      • paired atlantoaxial joints
  • Ligamentous structures
    • intrinsic ligaments are located within the spinal canal, provide most of the ligamentous stability. They include
      • transverse ligament  
        • primary stabilizer of atlantoaxial junction
        • connects the posterior odontoid to the anterior atlas arch, inserting laterally on bony tubercles. 
      • paired alar ligaments  
        • connect the odontoid to the occipital condyles
        • relatively strong and contributes to occipitalcervical stability
      • apical ligament  
        • relatively weak midline structure
        • runs vertically between the odontoid and foramen magnum.
      • tectorial membrane 
        • connects the posterior body of the axis to the anterior foramen magnum and is the cephalad continuation of the PLL
  • Neurovascular considerations
    • proximity of the occipital condyles to:
      • medulla oblongata
      • vertebral arteries
      • lower cranial nerves (CN IX - CN XII)
Classification
 
 Anderson and Montesano classification of occipital condyle fractures
Type I 3%  • Impaction-type fracture with comminution of the occipital condyle
 • Due to compression between the atlanto-odontoid joint
 • Stable injury due to minimal fragment displacement into the foremen magnum
   
Type II 22%  • Basilar skull fracture that extends into one- or both occipital condyles
 • Due to a direct blow to skull
 • Stable injury as the alar ligament and tectorial membrane are usually preserved
  
Type III 75%  • Avulsion fracture of condyle in region of the alar ligament attachment (suspect underlying occipitocervical dissociation)
 • Due to forced rotation with combined lateral bending.
 • Has the potential to be unstable due to craniocervical disruption
  
 
Harborview Classification of Craniocervical Injuries
Type I  • MRI shows craniocervical ligament injury
 • Craniocervical alignment is within 2mm of normal
 • <2mm of cervical distraction with traction
 
Type II  • MRI shows craniocervical ligament injury.
 • Craniocervical alignment is within 2mm of normal.
 • >2mm of cervical distraction with traction
 
Type III  • Craniocervical malalignment is greater than 2mm
 •  >2mm of cervical distraction with traction
 
 
Presentation
  • History
    • clinical presentation is highly variable
    • presentation is largely dependent on associated injury (eg, head injury, brainstem injury, vascular injury)
    • neurological deficits may be acute (63% of cases) or delayed (37% of cases)
  • Symptoms
    • high cervical pain
    • reduced head/neck ROM
    • torticollis
    • lower cranial nerve deficits
    • motor paresis
  • Physical Examination
    • lower cranial nerve deficits most commonly affect CN IX, X, and XI
Imaging
  • Radiographs
    • recommended views
      • AP, lateral, open-mouth AP view
    • alternative views
      • traction is generally not recommended
    • findings
      • diagnosis rarely made on plain radiographs due to superimposition of structures (maxilla, occiput) blocking view of occipital condyles
      • open-mouth AP view may depict occiptal condyle injuries
  • CT 
    • indications
      • method of choice
      • routine CT imaging in high-energy trauma patients
      • clinical criteria:
        • altered consciousness
        • occipital pain and tenderness
        • impaired CCJ motion
        • lower cranial nerve paresis
        • motor paresis
    • views
      • must include cranial-cervical junction with thin-section technique
    • findings
      • occiput fracture or CCJ instability
  • MRI
    • indications
      • evaluation of soft-tissue craniocervical trauma
      • fractured fragment located in the vertebral canal
      • spinal cord or brain stem ischemia
    • views
      • MR angiogram may be considered with suspected vascular injury
    • findings
      • MRI better than CT for the assessment of associated brain and brain-stem injuries, although CT still considered standard for evaluating acute subarachnoid hemorrhage
Treatment
  • Nonoperative
    • analgesics, cervical orthosis
      • indications
        • Type 1 and 2
        • Type 3 without overt instability
      • modalities
        • semi-rigid or rigid cervical collar
  • Operative
    • occipitocervical fusion
      • indications
        • Type 3 with overt instability
        • neural compression from displaced fracture fragment
        • associated occipital-atlantal or atlanto-axial injuries
      • technique
        • C0-C2/C3 occipitocervical arthrodesis using rigid segmental fixation or posterior decompression and instrumented fusion
        • may require bone grafting or removal of boney fragments compressing neurovascular structures. 
 

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