Anderson and Montesano classification of occipital condyle fractures (diagrams)

Case contributed by Assoc Prof Craig Hacking

Diagrams of the types of occipital condyle fractures.

Case Discussion

The Anderson and Montesano classification system divides injuries into three types based on morphology and mechanism of injury:

  • type I - comminuted (3-15%)
    • impaction fracture of occipital condyle
    • associated with axial compression injury
    • stable injury
  • type II - basilar skull (25-50%)
    • basilar skull fracture extending into the occipital condyle
    • associated with a direct blow to the lower skull
    • stable injury
  • type III - avulsion (35-75%)
    • condylar avulsion injury at the alar ligament attachment
    • associated with forced contralateral bending and rotation
    • potentially unstable injury

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