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.