Plain Film C-spine

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Introduction

Any physician who works in an acute management setting must be able to adequately work-up and manage C-spine injuries. C-spine X-rays are inexpensive to obtain and widely available, compared with other imaging modalities, so the work-up and diagnosis of a C-spine injury will most likely include their use.

 

Therefore, the physician treating a patient with a potential C-spine injury must be able to judiciously order and accurately read C-spine radiographs.

 

It is important to read C-spine X-rays in a stepwise fashion to ensure that nothing is overlooked. The first step, as with reading all forms of imaging, is to ensure that you have the correct patient and study date.

 

Next check that you have the appropriate views to rule-out injuries. A proper C-spine X-ray series should include at least 3 views:

The A-ABCS approach - Adequacy, Alignment, Bone, Cartilage, Soft tissue- can be helpful to evaluating each of these views, and will be described here.

 

  • AP view
  • lateral view
  • odontoid view

AP View

 

Adequacy

C3 – C7 must be visualized. C1 and C2 are seen on the odontoid view.

 

Alignment

The AP view has 5 “lines”:

  • The middle line follows the spinous processes. If the spinous processes do not line up, a facet fracture should be suspected.
  • The next two lines out from the middle trace the edge of the vertebral bodies right and left.
  • The last two lines are more lateral still and trace the articular pillars. Steps in these lines suggest C-spine fractures.

 

Bone

Visually trace the cervical vertebrae bodies. The cortex of each should be uninterrupted.

 

 

Cartilage/disc space

The spaces between vertebral bodies should be equal and symmetrical.

 

 

Soft Tissue

Soft tissues are difficult to interpret with this orientation.

 

Lateral Views

 

Adequacy

Most fatal C-spine injuries occur at C1, C2 (7). One third of C-spine injuries occur at C2, and half of C-spine injuries occur at C7 (7). On the lateral film, all of the cervical vertebrae must be visualized; the C7-T1 junction must be viewed. Soft tissue and bone should be distinguishable.

 

Alignment

There are 5 “lines” that can be seen on the lateral view:

  • the anterior edges of the vertebrae bodies
  • the posterior edges of the vertebrae bodies
  • the spinolaminar line (posterior spinal canal)
  • the posterior spinous line (posterior tips of the spinous processes).

These lines should be smooth and have a slight lordotic curve. Malalignment or steps suggest fractures or disruption of the spine ligaments.

 

 

Bone

Visually trace each vertebral body; the cortex of each should be uninterrupted. The base of dens should be intact. The C2-C7 vertebrae should all be roughly the same size. The anterior height and posterior height should be roughly equivalent. Trace the laminar bodies and the spinous processes as well. Again, the cortex of each vertebra should be uninterrupted. Pedicles, facets, and laminae should appear as one; if there is doubling, it suggests rotation.

 

 

Cartilage/disc space

The space between C1 and the dens of C2 (Atlas-Dens Interval, or ADI) should measure less than 3mm in adult patients, and <5mm in children (10). The spaces between the other vertebrae should be equal and symmetric.

 

 

Soft Tissue

The retropharyngeal space (C2-C4) should not exceed 7mm. It should be roughly half the width of a vertebral body. The retrotracheal space (C5-C7) should not exceed 22mm, which is roughly the full width of a vertebral body. Widening of these spaces is from soft tissue swelling, which is an indirect indication, and sometimes the only indication on X-ray, of a significant C-spine injury.

Odontoid view

 

Adequacy

All of C1 and C2, including the entire odontoid, which is also known as the “dens”, should be clearly visualized.

 

 

Alignment

The odontoid should be centred between the lateral bodies of C1 (equal lateral atlantodental interval). Asymmetry suggests a fracture in C1 or C2. Asymmetry may also be from positioning of the patient. If in doubt, get another odontoid view X-ray taken. The lateral edges of C1 should line up with the lateral edges of C2. If not, a fracture of C1 is suspected.

 

 

Bone

The odontoid should have an uninterrupted cortex.

 

 

Cartilage/disc space

The space between C1 and C2 should be symmetrical right and left.

 

 

Soft Tissue

Soft tissues are difficult to interpret with this orientation.

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Resources and References

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