Fractures and Dislocations: Dens

Fractures of the dens are commonly classified into 3 types with type II being the most common:

• TYPE 1 - Avulsion fracture of the tip. It is considered stable, but may represent detachment of the alar ligament (atlanto-occipital disassociation). Rare.
• TYPE II -   Fracture at base of ondontoid (poor blood supply kind of like scaphoid, non-union in 65%). Most Common. Poor blood supply. Unstable.
• TYPE III -  Fracture through  base of ondontoid into body of axis: (best prognosis for healing, but unstable.

Anterior tilt of ondontoid on lateral view is highly suspicious for fracture. 

Prevertebral soft tissue swelling may be the only sign.