Anderson and D'Alonzo classified fractures involving the odontoid process (dens) of the second cervical vertebra (axis). The authors are from the University of Tennessee and Campbell Foundation in Memphis.
Fracture Description
Type
oblique, running through the upper part of the odontoid process
I
transverse at the junction of the odontoid process with the vertebral body
II
fracture across the vertebral body, below the odontoid process
III
where:
• The transverse ligament of the atlas runs posterior to the dens and holds it in place relative to the atlas (C1).
• A Type I fracture would affect the attachment of an alar ligament.
Type I fractures are stable and can be managed with simple immobilization.
Type III fractures have a large surface area and can usually be managed with traction followed by bracing.
Type II fractures are the most common type, tend to be unstable and often are or become displaced. Non-union occurs in a third of patients treated conservatively.
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