C2 (Axis) Fractures Workup

Updated: Nov 21, 2018
  • Author: Igor Boyarsky, DO, FACEP, FAAEM; Chief Editor: Jeffrey A Goldstein, MD  more...
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Workup

Imaging Studies

The workup of suspected C2 (axis) fractures relies on imaging. Plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) are all employed. [7, 8]  Plain film views should include anteroposterior (AP), lateral, and odontoid views. [9, 10]  Additionally, some authors recommend oblique views to better assess the posterior elements. (For specific radiographic findings, see Pathophysiology and Classification.)

Plain films tend to be better than CT for detecting subluxations and dislocations; CT usually is better for detecting most fractures and for characterizing the extent of the pathology. Most of the fractures missed on CT are those oriented in the axial plane or those involving the odontoid process. Plain radiography also is better for detecting vertebral body and spinous process fractures.

Plain films are used routinely as the study of first choice; if pathology is found, CT usually is performed next to help define the extent of the injury. If the plain film studies are not diagnostic and clinical suspicion remains high, then further evaluation using CT is mandatory.

Some clinicians advocate the use of three-dimensional (3D) CT reconstruction as both a diagnostic aid and a surgical template. However, its role has yet to be characterized fully. The role of MRI in spinal trauma is to aid in the characterization of soft-tissue injury, neural element injury, and disk injury. This is the study of choice for the evaluation of ligamentous and spinal cord injury, and is mandatory in any trauma patient with a neurologic deficit.

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Classification

Levine and Edwards modified a classification system originally proposed by Effendi. This classification system categorizes C2 fractures on the basis of degree of displacement on lateral cervical spine (C-spine) radiographs and on mechanical stability. This system is useful in reconstruction of the injury mechanism and in mapping out a treatment.

Type I fractures are defined as follows:

  • Type I fractures (29%) are bilateral pedicle fractures with less than 3 mm of anterior C2 body displacement and no angulation
  • The mechanism of this injury is hyperextension with concomitant axial loading and a force sufficient enough to cause the fracture but not enough to disrupt the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), nor the C2/C3 disk
  • The integrity of the C2/C3 disk, ALL, and PLL determines the stability of the injury; with these elements intact, the injury is considered stable
  • Commonly associated concomitant injuries are C1 posterior arch fractures, C1 lateral mass fractures, and odontoid fractures

Type II fractures are defined as follows:

  • Type II fractures (56%) demonstrate significant displacement and angulation
  • The mechanism of this injury is twofold: hyperextension with concomitant axial loading, followed by flexion with concomitant axial compression
  • The resultant injury pattern is bilateral pedicle fractures with slight disruption of the ALL and significant disruption of the PLL and C2/C3 disk; this injury is considered unstable
  • A wedge compression fracture of C3 is the most common associated injury

Type IIA fractures are defined as follows:

  • Type IIA fractures (6%) demonstrate no anterior displacement, but there is severe angulation
  • The mechanism for this injury is flexion with concomitant distraction. The resultant injury pattern is bilateral pedicle fractures with C2/C3 disk disruption and some degree of insult to the PLL; this is an unstable fracture
  • Radiographs taken while the patient is in cervical traction demonstrate an increase in the C2/C3 posterior disk space

Type III fractures are defined as follows:

  • Type III fractures (9%) demonstrate severe displacement and severe angulation
  • The mechanism of this injury is flexion with concomitant axial compression
  • The resultant injury pattern demonstrates not only bilateral pedicle fractures with C2/C3 disk disruption, but also concomitant unilateral or bilateral C2/C3 facet dislocations
  • Varying degrees of injury occur to the ALL and PLL; this is an unstable fracture
  • Mortality and morbidity are relatively high with this injury; neurologic sequelae are particularly notable
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