Traumatic spondylolisthesis of the axis (hangman's fracture), type
Traumatic spondylolisthesis is the second most common injury of the
axis, following fractures of the odontoid.1
has been termed "hangman's fracture" due to its similarity to that
seen following judicial hangings. The most common causes are motor
vehicle accidents and falls.1
This injury is defined as bilateral avulsion of the neural
arches from the vertebral body, with or without subluxation. The
fracture is through the pars interarticularis of C2 or through the
adjacent portion of the articulating facet. The fracture may extend
into the posterior vertebral cortex or vertebral artery foramen.
The majority of cases of vertebral artery injury are clinically
The pars interarticularis is defined as the parts of the neural
arch that lie between the superior and inferior articular facets.
This is the site of fracture in traumatic spondylolisthesis, not
the pedicles or lateral masses, as is commonly
The mechanism of injury is most commonly hyperextension with
vertical compression, or forced hyperflexion with
compression.1,3 There is a high incidence of facial
injuries (commonly from windshields or dashboards) associated with
the hyperextension type of injury.1,4
The only differential diagnosis to consider is chronic
spondylolithesis of the axis. This is a rare disorder associated
with congenital abnormalities of the cervical
Several classification systems have been published; the most
widely used is the system devised by Effendi, and modified by
Levine and Edwards.1,5 Type 1 injuries have <3 mm of
displacement without angulation. The C2/C3 intervertebral disc is
normal. The mechanism of injury is hyperextension with axial
loading. Type 2 injuries are anteriorly angulated or displaced
fractures with disruption of the disc between C2 and C3. The
mechanism is combined hyperextension and axial loading followed by
hyperflexion. Type 2A injury is defined as significant angulation
without anterior translation. The mechanism is one of flexion and
distraction. Type 3 injuries involve anterior displacement with
hyperflexion of the axis associated with unilateral or bilateral
facet dislocations. The mechanism of the dislocation is flexion and
distraction, with hyperextension responsible for the
Lateral radiographs of the cervical spine reveal the fracture in
>90% of cases.1 Supervised flexion and extension
views may be helpful to evaluate for displacement or angulation.
Computed tomography is used to detect undisplaced fractures,
extension into the vertebral foramina and to localize displaced
Neurological injury is not commonly associated with this pattern
of injury, as the spinal canal is decompressed. The chance of
neurological damage increases with the severity of the injury.
However, significant neurological injury is possible even in type 1
injuries.1,3,5 If the fracture extends into the
transverse foramina, angiography may be indicated to exclude
vertebral artery dissection or intimal injury.3
Stability of the injury refers to the integrity of the anterior
and posterior ligament complexes. Type 1 fractures are considered
stable. The pattern of injury may be considered unstable if there
is >4 mm of anterior displacement or 11˚of angulation on
the initial radiograph. Further criteria for instability on the
lateral flexion extension views include >2 mm of translation or
Treatment is not universally agreed upon and differs depending
on the institution and surgeon. In general, type 1 injuries are
treated with a rigid collar for 8 to 12 weeks. Type 2 injuries are
initially reduced with traction in slight extension followed by a
halo vest for 12 weeks. A halo vest in compression and slight
extension is used for type 2A injuries. Immediate surgery is
required for type 3 injuries to stabilize the C2/C3 facet joint.
Surgery is also indicated in the case of failure of fusion after
Traumatic spondylolisthesis of the axis, also known as hangman's
fracture, is one of the most common cervical spine fractures
encountered in the trauma setting. The injury involves fractures
through the pars interarticularis of C2 bilaterally. The most
common mechanism of injury is hyperextension, and may be seen
following motor vehicle accidents or falls. The diagnosis can be
made on lateral conventional radio-graphs in the majority of cases.
CT is used to better define the extent of the fracture, or to
detect non-displaced fractures. Neurologic deficits are rare, but
possible. Involvement of the transverse foramina may injure the
- Pathria, MN. Physical injury: Spine. In: Resnick D, ed.
Diagnosis of Bone and Joint Disorders.4th ed. Philadelphia, PA:
W.B. Saunders Co.; 2002:2964-2967.
- Parke WW. Applied anatomy of the spine. In: Herkowitz HN, ed.
The Spine.4th ed. Philadelphia, PA: W.B. Saunders Co.;
- Mirvis SE, Young JWR, Lim C, Greenberg J. Hangman's fracture:
Radiologic assessment in 27 cases. Radiology.1987;163:713-717.
- Gelinas C, Levine AM. Upper cervical spine fractures and
instability. In: Chapman MW, ed. Chapman's Orthopaedic Surgery.3rd
ed. Philadelphia, PA: Lippincott Williams & Wilkins;
- Muller EJ, Wick M, Muhr G. Traumatic spondylolisthesis of the
axis: Treatment rationale based on the stability of the different
fracture types. Eur Spine J.2000;9:123-128.
- An HS. Cervical spine trauma. Spine.1998;23:2713-2729.
- Isolated fractures of the axis in adults.