Initial posting by: Bernard Bendok, MD
|This article has been reviewed by the NeuroWiki Editorial Board|
Atlas fractures may occur in isolation or in combination with C2 or other cervical fractures. Thin CT cuts from C1 through C3 is the best radiographic study to evaluate atlas fractures and rule out concomitant C2 injury. When examining AP or open mouth odontoid plain films, the rule of Spence is useful: if the total overhang of C1 lateral masses on C2 is greater than 7mm the transverse ligament is probably disrupted, requiring rigid immobilization. A Jefferson fracture usually results from an axial load injury through the arches and is unstable despite the fact that patients are neurologically intact. Axial forces tend to push bone fragments away from the spinal canal, which at the C1 level is composed of one-third dens, cord, and space according to Steele’s rule.
Isolated C1 Fractures
Generally do not require surgical stabilization. Fractures displaced greater than 7mm should be immobilized in a halo device, those with less than 7mm require either a rigid collar or halo, and non-displaced fractures may be treated with a soft or rigid collar.
Combination C1-C2 Fractures
Associated C2 injuries include hangman’s or dens (Type II or III) fractures. Treatment usually depends on type of C2 fracture; Type II odontoid with greater than 6mm displacement must be ruled out because this alone requires surgical fusion. Others may be treated with halo or SOMI brace. Atlantoaxial rotatory subluxation presents with torticollis, flattened face, and decreased ROM. It occurs spontaneaously or following minor or major trauma; rheumatoid arthritis patients are at increased risk. CT shows rotation of the atlas on the axis. Acute subluxation may be treated with traction but if present for greater than 3 months should receive halo fixation. Surgical C1-C2 fusion may be necessary in cases of recurrent or longstanding subluxation.