C1/C2 Fractures Flashcards
What is usually the mechanism of injury for a posterior arch fracture?
Hyperextension
What is the differential diagnosis for a posterior arch fracture?
Focal agenesis
What is the normal pattern and distribution of a posterior arch fracture?
Bilateral and vertical
What age population is more likely to have upper cervical fractures and why?
Elderly (due to orthostatic hypotension in the morning leading to face plant falls)
Why are neurological symptoms not usually seen with a posterior arch fracture?
Spinal canal actually widens therefore no compression on cord
What is the most common fracture of atlas?
Posterior arch fracture
What is a common cause of a posterior arch fracture in today’s society?
Rear end collision (MVA)
What is the differential diagnosis for a posterior arch fracture?
Focal agenesis
Why are posterior arch fractures not usually associated with neurological symptoms?
Spinal canal is WIDENED not narrowed
What is another name for a Jefferson fracture?
Bursting Fracture (C1)
What is the most common axial compression injury?
Jefferson Fracture
How many fractures make up the bursting fracture of C1?
Usually 4 (sometimes) 3: both the anterior and posterior arch
What film is used to diagnosis a Jefferson fracture?
APOM
What soft tissue is jeopardized with a Jefferson fracture?
Transverse atlantal ligament (unstable)
At what point does a Jefferson fracture become mechanically unstable?
If lateral masses are displaced more than 7mm (transverse atlantal ligament would be torn)
What is the maximum normal limit for the retropharyngeal space?
7mm
What mechanism causes an avulsion fracture of the anterior tubercle of atlas?
Hyperextension
Atlantoaxial dislocations are usually associated with what condition?
Rheumatoid arthritis (increased ADI)
What is the best view to assess for an increased ADI?
Cervical flexion
What “rule” divides the ring of atlas into 3 parts?
Steele’s Rule of Thirds
What are the 3 parts of Steele’s Rule of Thirds?
1/3 cord, 1/3 odontoid, 1/3 potential space
What is the most common type of fracture to occur at C2?
Odontoid fracture (40-50%)
What type of dens fracture is the most common?
Type II (66%)
What are the locations of all 3 types of dens fractures?
Type I = oblique fracture of tip
Type II = fracture at base
Type III = fracture into body
Which type of dens fracture has os terminale as a differential diagnosis?
Type I
Which type of dens fracture causing a disruption of Harris’ ring?
Type III
Which type of dens fracture is the most unstable?
Type II (type III also unstable when displacement is present)
Which type of dens fracture is stable?
Type I
Which type of dens fracture can be both stable or unstable?
Type III (depends on degree of displacement)
What are the differential diagnoses for odontoid fractures (mostly type II/III)?
Os odontoideum, mach effects
What causes an avulsion fracture of the odontoid tip (Type I odontoid fracture)?
Distraction by apical or alar ligaments
At what age does the normal ossification center at the tip of the dens disappear?
12
How can we tell the difference between an os terminale or a type I odontoid fracture?
Cortex lining = os terminal or old fracture; jagged edges mean acute fracture
A type II odontoid fracture is best seen on what X-ray view?
APOM
A type II odontoid fracture must be displaced how much to be considered incapable of healing by itself and therefore requiring intervention?
More than 5mm
What is unique about the majority of os odontoideums?
Most are old ununited dens fractures
What is the most important thing to consider with any case of a type II odontoid fracture?
Atlantoaxial instability
CT imaging is done in what plane?
Axial
If a type II dens fracture is suspected, what further imaging should be done to confirm and why?
CT (both CT and fracture are found in the axial plane)
On which view is a type III odontoid fracture best seen?
Lateral
Why do C2 odontoid fractures most commonly occur at the base?
Area of least cortex (thinnest)
What is a Hangman’s fracture?
Bilateral pedicle fractures of C2
What mechanism causes a Hangman’s fracture?
Hyperextension
What type of displacement results with a Hangman’s fracture?
Anterior displacement of C2
Are neurological symptoms present with a Hangman’s fracture?
No (canal is widened by anterior displacement)
What soft tissue mass can be increased with a Hangman’s fracture?
Retropharyngeal space (should be less than 7mm)
