odontoid fracture

Last reviewed 01/2018

Fractures of the odontoid peg of the axis (C2) may result from extension of the neck in a high-velocity accident or a severe fall. They are difficult to diagnose and should be suspected from the history in association with local pain and protective muscle spasm.

In the majority of cases the diagnosis is confirmed on AP 'through the mouth' and lateral x-rays. In some cases tomography may be necessary. Confusion may arise because of congenital abnormalities including non-fusion of the odontoid process. Be careful not to mistake the vertical cleft between the incisors or the epiphyses in children for a fracture.

Odontoid fractures can be classified as follows:

  • type I:
    • involving the tip of the odontoid peg
    • are stable and require only symptomatic treatment with a collar

  • type II:
    • involving the junction of the odontoid peg with the body
    • are the commonest type
    • require reduction and immobilisation with a Halo and body cast
    • if at 12 weeks the fracture is still unstable posterior fusion of C1 to C2 is advisable

  • type III:
    • this type of fracture runs deeply into the body of C2
    • union fails to occur in about 25% of cases
    • management is as for type II fractures