Odontoid fractures
Original Editors
Top Contributors - Sofie Christiaens, Kim Jackson, Rachael Lowe, Claire Knott, 127.0.0.1, Tassignon Bruno, WikiSysop and Karen Wilson
Search Strategy[edit | edit source]
Key words: C2 vertebra, anatomy cervical spine, C2 axis, anatomy C2, odontoid fractures, odontoid fractures AND causes, odontoid fractures AND clinical presentation, odontoid fractures AND characteristics, dens fractures AND classification, odontoid fractures management (conservative/surgical)
Search engines: Pubmed, Limo, google books (can be useful)
Definition/Description[edit | edit source]
The odontoid process, also called the dens, is a protuberance of the axis. Fractures can appear because of forces acting on this anatomical structure.
Clinically Relevant Anatomy[edit | edit source]
The C2 vertebra or axis is one of three atypical vertebrae. The axis shows a peg-like dens (odontoid process) who projects itself superiorly from its body. The dens lies anterior to the spinal cord and is used as the pivot for the rotation of the head. C1, carrying the cranium, rotates on C2. This rotation takes place on the two superior articular facets. This craniovertebral joint between the atlas and the axis is called, the atlanto-axial joint. The craniovertebral joints distinguish themselves of the others vertebral joints because they do not have intervertebral discs; therefore they possess a wider range of motion than the rest of the vertebral column. The dens of the axis and anterior arch of the atlas are held together by the transverse ligament of the atlas. This ligament prevents anterior displacement of C1 and posterior displacement of C2. If any displacement of this form would occur the spinal cord can be compromised due to the narrowing of the vertebral foramen. Structures that cannot be forgotten are the cervical nerves who pass above and underneath the axis; these nerves are crucial for both the head as the respiratory system (diaphragm).
Epidemiology /Etiology[edit | edit source]
Fractures of the dens represent almost 15% of all cervical spine injuries. It can be seen both in young patients due to a high-energy trauma (e.g. a motor vehicle accident) and in elderly patients due to a low-energy trauma (e.g. a fall). Furthermore, it is the most common fracture of the axis. Looking at the different types, type I occurs very rarely. Type II fractures, on the other hand, are the most frequent. This injury can be associated with various aetiologies. One of the underlying mechanisms is hyperextension of the neck. Other possible causes are a blunt trauma or hyperflexion trauma.
Characteristics/Clinical Presentation[edit | edit source]
Typically, patients with an odontoid fracture complain about neck pain. Neurological disorders are exceptional, but they can occur when the fractured dens is displaced. Based on the anatomic location of the fracture line, three types can be distinguished. This is called the Anderson and D’Alonzo classification.
-Type I: avulsion fracture of the apex. Stable injuries.
-Type II: fracture through the base of the dens, at the junction of the odontoid base and the body of C2. Often unstable injuries.
-Type III: fracture extends into the body of the axis. Usually stable injuries.
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