Odontoid fracture

Odontoid process fracture, also known as a peg or dens fracture, occurs where there is a fracture through the odontoid process of C2.


The mechanism of injury is variable, and can occur both during flexion or extension, and with or without compression 5.


There are two classification systems 5,6

  • Anderson and D'Alonzo
    • most commonly used
    • describes level of fracture line (i.e. through tip, base, or lateral masses)
  • Roy-Camille classification
    • has been shown to better correlate with prognosis
    • describes plane of fracture and displacement

Differential diagnosis

Spinal trauma

Article information

rID: 6370
Synonyms or Alternate Spellings:
  • Odontoid process fracture
  • Dens fracture
  • Odontoid peg fracture
  • Odontoid fractures
  • Odontoid peg fractures
  • Dens fractures
  • Odontoid process fractures
  • Anderson and D'Alonzo classification

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Figure 1: Anderson and D'Alzonzo classification
    Drag here to reorder.
  • Case 1
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Odontoid Fracture...
    Case 3: type II
    Drag here to reorder.
  • Case 4: type III
    Drag here to reorder.
  • Case 5
    Drag here to reorder.
  • Case 6: type II
    Drag here to reorder.
  • Case 7: type II
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.