C1/C2 Fractures

Question 1

What is usually the mechanism of injury for a posterior arch fracture?

Answer 1

Hyperextension

Question 2

What is the differential diagnosis for a posterior arch fracture?

Answer 2

Focal agenesis

Question 3

What is the normal pattern and distribution of a posterior arch fracture?

Answer 3

Bilateral and vertical

Question 4

What age population is more likely to have upper cervical fractures and why?

Answer 4

Elderly (due to orthostatic hypotension in the morning leading to face plant falls)

Question 5

Why are neurological symptoms not usually seen with a posterior arch fracture?

Answer 5

Spinal canal actually widens therefore no compression on cord

Question 6

What is the most common fracture of atlas?

Answer 6

Posterior arch fracture

Question 7

What is a common cause of a posterior arch fracture in today’s society?

Answer 7

Rear end collision (MVA)

Question 8

What is the differential diagnosis for a posterior arch fracture?

Answer 8

Focal agenesis

Question 9

Why are posterior arch fractures not usually associated with neurological symptoms?

Answer 9

Spinal canal is WIDENED not narrowed

Question 10

What is another name for a Jefferson fracture?

Answer 10

Bursting Fracture (C1)

Question 11

What is the most common axial compression injury?

Answer 11

Jefferson Fracture

Question 12

How many fractures make up the bursting fracture of C1?

Answer 12

Usually 4 (sometimes) 3: both the anterior and posterior arch

Question 13

What film is used to diagnosis a Jefferson fracture?

Answer 13

APOM

Question 14

What soft tissue is jeopardized with a Jefferson fracture?

Answer 14

Transverse atlantal ligament (unstable)

Question 15

At what point does a Jefferson fracture become mechanically unstable?

Answer 15

If lateral masses are displaced more than 7mm (transverse atlantal ligament would be torn)

Question 16

What is the maximum normal limit for the retropharyngeal space?

Answer 16

7mm

Question 17

What mechanism causes an avulsion fracture of the anterior tubercle of atlas?

Answer 17

Hyperextension

Question 18

Atlantoaxial dislocations are usually associated with what condition?

Answer 18

Rheumatoid arthritis (increased ADI)

Question 19

What is the best view to assess for an increased ADI?

Answer 19

Cervical flexion

Question 20

What “rule” divides the ring of atlas into 3 parts?

Answer 20

Steele’s Rule of Thirds

Question 21

What are the 3 parts of Steele’s Rule of Thirds?

Answer 21

1/3 cord, 1/3 odontoid, 1/3 potential space

Question 22

What is the most common type of fracture to occur at C2?

Answer 22

Odontoid fracture (40-50%)

Question 23

What type of dens fracture is the most common?

Answer 23

Type II (66%)

Question 24

What are the locations of all 3 types of dens fractures?

Answer 24

Type I = oblique fracture of tip
Type II = fracture at base
Type III = fracture into body

Question 25

Which type of dens fracture has os terminale as a differential diagnosis?

Answer 25

Type I

Question 26

Which type of dens fracture causing a disruption of Harris' ring?

Answer 26

Type III

Question 27

Which type of dens fracture is the most unstable?

Answer 27

Type II (type III also unstable when displacement is present)

Question 28

Which type of dens fracture is stable?

Answer 28

Type I

Question 29

Which type of dens fracture can be both stable or unstable?

Answer 29

Type III (depends on degree of displacement)

Question 30

What are the differential diagnoses for odontoid fractures (mostly type II/III)?

Answer 30

Os odontoideum, mach effects

Question 31

What causes an avulsion fracture of the odontoid tip (Type I odontoid fracture)?

Answer 31

Distraction by apical or alar ligaments

Question 32

At what age does the normal ossification center at the tip of the dens disappear?

Answer 32

12

Question 33

How can we tell the difference between an os terminale or a type I odontoid fracture?

Answer 33

Cortex lining = os terminal or old fracture; jagged edges mean acute fracture

Question 34

A type II odontoid fracture is best seen on what X-ray view?

Answer 34

APOM

Question 35

A type II odontoid fracture must be displaced how much to be considered incapable of healing by itself and therefore requiring intervention?

Answer 35

More than 5mm

Question 36

What is unique about the majority of os odontoideums?

Answer 36

Most are old ununited dens fractures

Question 37

What is the most important thing to consider with any case of a type II odontoid fracture?

Answer 37

Atlantoaxial instability

Question 38

CT imaging is done in what plane?

Answer 38

Axial

Question 39

If a type II dens fracture is suspected, what further imaging should be done to confirm and why?

Answer 39

CT (both CT and fracture are found in the axial plane)

Question 40

On which view is a type III odontoid fracture best seen?

Answer 40

Lateral

Question 41

Why do C2 odontoid fractures most commonly occur at the base?

Answer 41

Area of least cortex (thinnest)

Question 42

What is a Hangman's fracture?

Answer 42

Bilateral pedicle fractures of C2

Question 43

What mechanism causes a Hangman's fracture?

Answer 43

Hyperextension

Question 44

What type of displacement results with a Hangman's fracture?

Answer 44

Anterior displacement of C2

Question 45

Are neurological symptoms present with a Hangman's fracture?

Answer 45

No (canal is widened by anterior displacement)

Question 46

What soft tissue mass can be increased with a Hangman's fracture?

Answer 46

Retropharyngeal space (should be less than 7mm)