Pediatric emergency medicine trisk 3602 3602

A Jefferson fracture is a bursting fracture of the ring of C1 as a result of an axial
load. The ring of C1 is compressed between the occipital condyles of the skull and
the lateral masses of C2. This process can cause an outward burst of C1, but it
rarely causes immediate neurologic impairment because the fracture does not
physically impinge on the spinal cord. The radiographic criterion for the diagnosis
of a Jefferson fracture is lateral offset of the lateral mass of C1 of more than 1 mm
from the vertebral body of C2 ( Fig. 112.22 ). Neck rotation may give a falsepositive radiographic finding. These fractures may be unstable, however, and
require adequate immobilization. If the transverse ligament is intact, the fracture
may be relatively stable, whereas if the transverse ligament is injured and there is
an increased distance between the lateral masses and the odontoid process, it
should be considered unstable. A reduced AP diameter of the cervical spinal canal
is also associated with spinal cord injury. Approximately one-third of Jefferson
fractures are associated with other cervical spine fractures, most often involving
C2. The clinician must be aware of the pseudo-Jefferson fracture of childhood,
which is present in 90% of children at 2 years of age and usually normalizes by 4
to 6 years of age. The pseudo-Jefferson fracture has the radiographic appearance
of a Jefferson fracture because of increased growth of the atlas (C1) compared
with the axis (C2) and radiolucent cartilage artifact. This disorder can present with
unilateral or bilateral lateral mass offset. If a Jefferson fracture is suspected by
radiographic findings and mechanism of injury in children younger than 4 years, a
CT scan may be necessary to further elucidate the suspected injury ( Fig. 112.23 ).