Atlantoaxial Rotary Subluxation and Dislocation

In this rare injury, patients present with confusing complaints of neck pain, occipital neuralgia, and, occasionally, symptoms of vertebrobasilar insufficiency. In chronic cases, the patient may present with torticollis.

It is infrequently associated with neurologic injury.

The mechanism of injury is flexion/extension with a rotational component, although in some cases it can occur spontaneously with no reported history of trauma.

Odontoid radiographs may show asymmetry of C1 lateral masses with unilateral facet joint narrowing or overlap (wink sign). The C2 spinous process may be rotated from the midline on an AP view.

The subluxation may be documented on dynamic CT scans; failure of C1 to reposition on a dynamic CT scan indicates fixed deformity.

Classification (Fielding)

Type I: Odontoid as a pivot point; no neurologic injury; ADI <3 mm; transverse ligament intact (47%)

Type II: Opposite facet as a pivot; ADI <5 mm; transverse ligament insufficient (30%)

Type III: Both joints anteriorly subluxed; ADI >5 mm; transverse and alar ligaments incompetent

Type IV: Rare; both joints posteriorly subluxed

Type V: Levine and Edwards: Frank dislocation; extremely rare

Treatment

• Cervical halter traction in the supine position and active range-of-motion exercises for 24 to 48 hours initially are followed by ambulatory orthotic immobilization with active range-of-motion

  exercises until free motion returns.

• Rarely, fixed rotation with continued symptoms and lack of motion indicates a C1–C2 posterior fusion.