| Classification | Description | Notes |
| Type 1 | Oblique fracture through the odontoid tip | Stable |
| Type 2 | Fracture through the base of the dens | Unstable. Higher risk of nonunion with comminuted fracture, age > 50 or more than 5mm displacement |
| Type 3 | Fracture through the body of C2 | Will heal with immobilization, but may have residual spinal stenosis |
References:
Dreizin, D., et al. (2014). “Multidetector CT of blunt cervical spine trauma in adults.” Radiographics 34(7): 1842-1865.
Anderson LD, D’Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974;56(8):1663–1674.