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The Lateral Cervical Spine X-Ray

The normal cross-table lateral cervical spine X-ray must visualise the entire cervical spine, from the skull base to the cervico-thoracic junction. A film that does not show the upper border of T1 is inadequate and should be repeated or supplemented with a swimmer's view (flying angel). Caudad traction on the arms will improve the view obtained - someone else should stabilise the patient's head and pelvis during the X-Ray.

Normal Lateral Cervical Spine
Normal Lateral

Next, examine the alignment of the columns of the cervical spine. The anterior vertebral line, posterior vertebral line and spinolaminar line should have a smooth curve with no steps or discontinuities. Note that malalignment of the posterior vertebral bodies is more significant than that anteriorly, which may be due to rotation. A translation of > 3.5mm is significant anywhere. Spinal canal diameter (between posterior cortex of vertebral bodies and spinolaminar line) should be 18mm or greater. Narowing of the canal is definitely present if this is reduced to 14mm or less.


Anterior subluxation of one vertebra on another indicates facet dislocation. Less than 50% of the width of a vertebral body and this is a unifacet dislocation. More than 50% is a bilateral facet dislocation. This is usually accompanied by widening of the interspinous and interlaminar spaces.

Unifacet Dislocation Bifacet Dislocation

Examination of the vertebral bodies and the intervertebral disc space will reveal compression and burst type injuries. Bodies should be regular cuboids similar in size and shape to the vertebrae immediately above and below (not C1/C2). Compression fractures may present as anterior wedging of the vertebral body or teardrop fractures of the antero-inferior portion of the body (compression in flexion).

C4 compression & teardrop

The presence of a compression type injury as shown, with malalignment of the anterior or posterior cortices or anterior compression of greater than 40% of normal body height indicates a burst fracture, with retropulsion of fragments of the vertebral body into the spinal canal.

Loss of height of an intervertebral disc space, when compared to adjacent spaces may indicate disc herniation - usually posteriorly into the canal. Analysis of the prevertebral soft tissues may allow the diagnosis of cervical injuries from very subtle changes on the lateral film. The soft tissue shadow is created by the pharyngeal and prevertebral tissues, with the posterior larynx and oesophagus thickening the shadow below C4. Above C4 the width of the shadow should be less than 50% of the width of a vertebral body, while below C4 the limit is one full vertebral body width.

Atlanto-occipital Disassociation

Atlanto-occipital disassocation can be very difficult to diagnose and is easily missed. The distance from the occiput to the atlas should not exceed 5mm anywhere on the film.

Atlanto-occipital Disassociation

The odontoid peg must also be specifically examined for fractures. Soft tissue swelling anterior to the arch of C1 will suggest the presence of a fracture at this level. The Atlanto-Dens Interval (ADI) in adults should be < 3mm (in flexion). Shift of more than 3.5mm implies injury to the transverse ligament, and more than 5mm indicates complete rupture and instability. The C1-C2 interspinous space should not be more than 10mm wide.