Fracture of dens.(Type II)

Dens fractures are classified according to the scheme of Anderson and D\'Alonzo. They are the result of severe forces including rotation across the cervical spine.

TYPES-

Type I is an avulsion fracture arising from the tip of the dens at the site of the alar ligaments. rare form. Rarely complicated by non union.

Type II (high) is a fracture at the base without extension to the body of C2. Most common type, associated with non union due to reduced vascularity separated fragments.

Type III (low) is a fracture through the body of C2, not actually involving the dens. It is as common as type II though it heals radially.

 

RADIOLOGY-

Plain Film

Lateral-Fracture line

             Fragmentation

             Anteroposterior displacement

             Disrupted posterior cervical line, axis ‘ring’

             Enlarged axis body (fat C2)

             Retropharyngeal swelling.

Frontal- Fracture line.

              Tilted odontoid process (> 5degree)

              Osteolysis of odontoid.

 

CT- Displacement of odontoid

        Comminution of axis.

        Prevertebral swelling.

        Central canal is compromised.

        Intra spinal hematoma.

 

MRI- Vertebral marrow signal changes

           Spinal canal and cord integrity.

          Intraspinal hematoma.