THÔNG TIN TÀI LIỆU
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 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 years of age and usually normalizes by to 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 years, a CT scan may be necessary to further elucidate the suspected injury ( Fig 112.23 )
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