Imaging of the Cervical Spine > Fractures > Ant. Subluxation

Anterior Subluxation

Description: disruption of the posterior ligamentous complex resulting from hyperflexion. It may be difficult to diagnose because muscle spasm may result in similar findings on the radiograph. Subluxation may be stable initially, but it associates with 20%-50% delayed instability. Flexion and extension views are helpful in further evaluation.

Mechanism: hyperflexion of neck

Radiographic features:

1. Loss of normal cervical lordosis.
2. Anterior displacement of the vertebral body.
3. Fanning of the interspinous distance.

Radiographic features of unstable injury:

1. Anterior subluxation of more than 4mm.
2. Associated compression fracture of more than 25 % of the affected vertebral body.
3. Increase or decrease in normal disk space.
4. Fanning of the interspinous distance.