Volume 5, Case 3
Linton L. Yee, MD
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
A 7-year-old female is brought in by paramedics in full C-spine immobilization after being involved in a motor vehicle accident. According to her parents, the unrestrained child was sitting in her restrained mother's lap on the passenger side when the passenger side of the car was broadsided by another vehicle. The child's head was thrown into the dashboard, and she sustained severe injuries to the face and scalp.
Upon arrival in the ED, the patient is crying and responsive to all stimuli. There are multiple facial lacerations, a large scalp laceration, and facial edema/ecchymosis.
A lateral neck radiograph is taken.
View lateral neck radiograph.
The hangman's fracture is an unstable fracture of the C2 pedicles, with forward displacement of C1 and the body of C2 on C3. This traumatic spondylolisthesis of C2 is the result of hyperextension of the head relative to the neck.
Motor vehicle accidents, hanging and hyperextension can cause these fractures by creating a hyperextension or flexion force (leverage) of the cervical spine as a fulcrum. The upper portion of the cervical spine (skull, C1, C2) then separates from the lower cervical spine. Hyperextension will initially cause fracture of the C2 neural arch (pedicles) and disruption of the anterior ligaments. The return to neutral position will then cause the body of C2 to become anteriorly displaced over C3.
Lateral neck radiographs are extremely helpful, and the fracture of the neural arch is usually easily seen. Oblique views are also helpful. AP views do not contribute much. CT scans are not as helpful as in other cervical fractures.
If the neural arch fracture is not evident on the lateral neck view in a hangman's fracture, it may resemble a benign "pseudosubluxation" of C2 on C3. It is essential to properly identify a hangman's fracture. DO NOT mistake this for a "pseudosubluxation". Refer to Case 5 of Volume 1 (Cervical Spine Malalignment - True or Pseudo Subluxation ?) for a more detailed discussion of cervical spine "pseudosubluxations".
View the anatomic markers on the lateral neck radiograph.
The white arrow points to the fracture of the pedicle (neural arch) of C2.
In the lateral neck radiograph of a hangman's fracture, the C2 vertebral body is displaced superiorly, and the inferior articular facets of C2 are displaced inferiorly. The C2 pedicle fractures are anterior to the inferior articular facets and posterior to the superior articular facets. With the loss of bony support, the C2 vertebral body will usually move anteriorly relative to C3.
The diagram shows three lines drawn along the cervical spine. From left to right on the diagram, these are the anterior cervical line, the posterior cervical line, and the spinolaminal line. A fourth line that is often drawn over the spinous processes is not shown here. These lines show only minimal disruption in the C2-C3 region.
In a hangman's fracture, the anterior and posterior cervical lines will usually be abnormal because of the anterior displacement of C2 on C3.
The spinolaminal line is usually not intact between the C2 spinous process base and the C1 posterior arch, with the posterior arch of C1 displaced anterior to the C2 spinous process base. This is the result of the C2 body carrying the odontoid process when it moves forward on C3. C1 and the skull follow the C2 forward movement because the occipitoatlantoaxial joints are not damaged.
The spinolaminal line from C2 to C7 may remain intact because the inferior articular facets of C2 remain in their usual location, and the apophyseal joints between the C2 inferior articular facets and the C3 superior articular facets remain unchanged.
A patient with a C2 hangman's fracture may present in a variety of ways, often with a strong association with facial and scalp injuries.
In a patient with a hangman's fracture, when the fracture of the neural arch (pedicle) of C2 is not visible on the lateral neck view (an uncommon occurrence), the only evidence of the fracture may be modest malalignment of C2-C3. This can also be seen in a benign pseudosubluxation. Distinguishing a benign C2-C3 pseudosubluxation from a TRUE subluxation associated with a hangman's fracture is critical. Refer to Case 5 of Volume 1 (Cervical Spine Malalignment - True or Pseudo Subluxation ?) for a more detailed discussion of cervical spine "pseudosubluxations".
In general, the C2-C3 pseudosubluxation differs from the hangman's fracture in several ways:
1. The injury mechanism history for a pseudosubluxation is generally more benign. A hangman's fracture is typically an acceleration/deceleration mechanism (motor vehicle crash) or a hanging mechanism.
2. Clinically, a patient with a pseudosubluxation will appear to have sustained much less trauma than a patient with a hangman's fracture.
3. A pseudosubluxation is ONLY seen on lateral neck radiograph views that are positioned without lordosis (i.e., in flexion, or neutral). If C2-C3 malalignment is noted on a lateral neck radiograph with good lordotic (extension) positioning, this is probably a TRUE subluxation (a hangman's fracture), and NOT a pseudosubluxation. Since the occiput of most children is large, most lateral neck radiographs taken on children strapped to spine boards, will frequently show the neck in neutral or flexed positioning.
4. A visible fracture of the neural arch is usually evident on the lateral neck view in a hangman's fracture. The absence of a visible fracture does not rule out a hangman's fracture since it may be difficult to visualize radiographically at times.
5. The Swischuk line, may be helpful in identifying some hangman's fractures. This line is drawn from the anterior aspect of the posterior arch of C1 to the anterior aspect of the posterior arch of C3. The anterior aspect of the posterior arch of C2 should be within 1-2 mm of this line. If it is deviated more than 2 mm, this is indicative of a true subluxation. If it is deviated less than 2 mm, this is consistent with a pseudosubluxation, but this alone is insufficient to rule out a hangman's fracture. Note that in our patient with the hangman's fracture, the Swischuk line is in good alignment in the presence of a hangman's fracture.
View Swischuk line.
The left image is our patient with the hangman's fracture. The right image is a normal patient whose neck is positioned in flexion showing C2-C3 pseudosubluxation. The Swischuk lines are in good alignment in both images.
6. Clinically, if one is confident that a pseudosubluxation is the reason for the C2-C3 malalignment, one could reposition the patient to obtain a repeat lateral neck radiograph in extension (lordosis). If the C2-C3 malalignment resolves, this is consistent with a pseudosubluxation. If the C2-C3 malalignment persists, this is consistent with a true subluxation. However, this maneuver is often not clinically useful since cervical spine movement should be minimized until cervical spine fractures and/or instability have been ruled out.
7. In uncertain cases, a CT or MRI scan may be necessary to rule out a hangman's fracture.
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