Odontoid fracture type II (Anderson-D’Alonzo classification)

Case contributed by Domenico Nicoletti
Diagnosis certain

Presentation

Victim of motorcycle accident.

Patient Data

Age: 75 years
Gender: Male
Frontal
Lateral
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Cervical spine

X-rays of the cervical spine (lateral without open mouth views) showing displaced and posteriorly angulated odontoid fracture.

This study is a stack
Axial bone
window
This study is a stack
Axial soft
tissues window
This study is a stack
Coronal
bone window
This study is a stack
Sagittal
bone window
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Imaged in collar. Type II odontoid fracture with backward displacement and backward angulation. There are also possible bilateral undisplaced posterior arch fractures of C1 (with a typical variant posterior midline non-fusion).

Case Discussion

Fracture across base of the odontoid process is below the transverse / cruciate ligament, and it is usually unstable. Type II odontoid fractures occur when the cervical spine is hyperflexed or hyperextended. Hyperflexion and hyperextension can be caused by trauma such as a fall or whiplash from a motor vehicle accident. They are the most common type of cervical spine fractures in patients older than 70. This is probably due to the increased risk of falls in the elderly, as well as the greater incidence of osteoporosis.

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