Cervical spine X-ray

Written by the X-Ray Atlas editorial team from the sources listed below · Medical review pending · Updated 24 October 2026 · Level: Intermediate

A missed cervical spine injury can mean permanent paralysis, so this is one of the highest-stakes films in emergency medicine. Two things have changed how it is used. First, clinical decision rules (the Canadian C-spine rule and NEXUS) identify patients who need no imaging at all. Second, in the UK, NICE NG232 (2023) recommends CT, not plain radiographs, as the first-line imaging for adults who need C-spine imaging after trauma. Plain films are now used mainly in children, in some lower-risk settings and outside the acute trauma pathway. You still need to read them well: they remain common, and the same anatomy underpins CT interpretation.

1. Who needs imaging, and which test?

Decision rules

• Canadian C-spine rule (alert, stable adults): imaging is indicated for any high-risk factor: age 65 or over, a dangerous mechanism (for example a fall from 1 m or five stairs, an axial load to the head, a high-speed or rollover collision, ejection, a motorised recreational vehicle or bicycle collision) or paraesthesia in the limbs. If there is none, low-risk factors are sought that allow safe assessment of movement, and finally the patient must be able to actively rotate the neck 45° left and right.
• NEXUS: no imaging is needed if all five criteria are met: no posterior midline cervical tenderness, no focal neurological deficit, normal alertness, no intoxication, and no painful distracting injury.

Which test (UK)

NICE NG232 uses the Canadian C-spine rule to decide who needs imaging in adults and recommends CT as the imaging test for adults, because plain films miss a meaningful proportion of injuries and are often inadequate at the craniocervical and cervicothoracic junctions. For children under 16, NG232 sets separate criteria: CT for higher-risk children, and plain radiographs may be appropriate in some lower-risk cases. MRI is used for suspected ligamentous or cord injury and in specific situations. Guidance changes, so always check the current NG232 and your local trauma policy.

2. A: Adequacy and alignment

The standard trauma series is a lateral, an AP and an open-mouth odontoid (peg) view.

• Adequacy: the lateral must show from the skull base (clivus) to the top of T1, including the C7/T1 junction. The lower cervical spine is often hidden by the shoulders; a swimmer's view (one arm raised) may show it. If C7/T1 is not seen, the film is inadequate, and you must say so. The peg view should show the dens and the lateral masses of C1 and C2.
• Alignment: on the lateral, four smooth curves should be present:
  1. the anterior vertebral line (anterior margins of the vertebral bodies);
  2. the posterior vertebral line (posterior margins, the front of the spinal canal);
  3. the spinolaminar line (where the laminae meet the spinous processes, the back of the canal);
  4. the line along the tips of the spinous processes.

Any step should be explained. As a rule of thumb from the White and Panjabi criteria, a translation of more than about 3.5 mm, or angulation of more than about 11° between adjacent levels, suggests instability.

3. B: Bones

• Trace the outline of each vertebral body: is the height preserved, and is the anterior height similar to the posterior?
• Check the posterior elements: pedicles, lateral masses, laminae and spinous processes.
• On the lateral, look at C1 and C2 carefully: the anterior arch of C1, the dens, and the ring of C2 (a rough ring outline seen over the C2 body; a break suggests a fracture of the base of the dens or body).
• On the peg view, the lateral masses of C1 should line up with those of C2 on both sides, and the dens should sit centrally between them.

4. C: Cartilage and joints

• Disc spaces should be similar in height at each level. A narrowed disc may be degenerative, but an unexpectedly widened disc space after trauma can mean ligament disruption.
• Facet joints should overlap neatly like roof tiles. An abrupt change in their appearance at one level, or a "bow-tie" double outline, suggests a rotational facet injury.
• Interspinous distances: abnormal widening ("fanning") at one level suggests posterior ligamentous injury.
• Atlanto-dental interval (predental space), between the back of the anterior arch of C1 and the front of the dens: about ≤3 mm in adults and ≤5 mm in children. Wider suggests transverse ligament injury.

5. S: Soft tissues

Swelling in front of the spine (prevertebral soft tissue) can be an indirect sign of a fracture or ligament injury.

6. Key injuries

Injury	Mechanism	X-ray features	Stability
Jefferson fracture (C1 burst)	Axial load	Fractures of the anterior and posterior arches of C1. On the peg view the lateral masses of C1 overhang C2. A combined overhang of more than about 6.9 mm (the "rule of Spence", often rounded to 7 mm) has been used to suggest transverse ligament rupture; CT and MRI have largely superseded this rule.	Potentially unstable
Odontoid (peg) fracture	Flexion or extension	Anderson and D'Alonzo: type I tip avulsion (rare, stable); type II at the base of the dens (the commonest, with high non-union risk); type III extending into the body of C2 (better healing)	Type II and III potentially unstable
Hangman's fracture	Hyperextension	Bilateral fractures through the pars interarticularis of C2, with or without anterolisthesis of C2 on C3	Variable
Flexion teardrop	Severe flexion with axial load	A triangular fragment from the antero-inferior corner of a vertebral body, with the rest of the body displaced backwards into the canal	Highly unstable; anterior cord syndrome
Extension teardrop	Hyperextension	A fragment avulsed from the antero-inferior corner, classically of C2, by the anterior longitudinal ligament	Usually more stable; do not confuse with flexion teardrop
Unifacet dislocation	Flexion with rotation	Anterolisthesis of less than 50% (often about 25%) of the vertebral body width; rotation, with a "bow-tie" appearance of the facets	Potentially unstable
Bifacet dislocation	Severe flexion	Anterolisthesis of more than 50%	Highly unstable; high risk of cord injury
Wedge compression fracture	Flexion	Loss of anterior body height; look for associated posterior ligamentous injury	Usually stable if isolated
Clay-shoveler's fracture	Flexion or direct blow	Avulsion of the spinous process of C7 (or C6 or T1)	Stable

Atlanto-occipital dissociation (craniocervical dislocation) is rare and often fatal. Markers include an increased basion-dens interval (often quoted as above about 12 mm) and an abnormal Powers ratio. CT is the test.

7. Children

• Pseudosubluxation of C2 on C3 (and sometimes C3 on C4) is normal up to about age 8. The Swischuk line (the posterior cervical line), drawn from the anterior cortex of the C1 spinous process to that of C3, should pass within about 2 mm of the anterior cortex of the C2 spinous process. More than that suggests a true injury, such as a hangman's fracture.
• The predental space can be up to about 5 mm.
• Unfused synchondroses of C2 and the dens can mimic fractures.
• SCIWORA (spinal cord injury without radiographic abnormality): a child can have a cord injury with normal radiographs and sometimes normal CT. Neurological signs need MRI.

See Salter-Harris fractures and the paediatric modules.

8. Pitfalls

• Accepting an inadequate film. Most missed injuries on plain films are at C1/C2 and C7/T1, exactly where films are often incomplete.
• Mach bands and overlapping teeth or the posterior arch of C1 can mimic a peg fracture. Os odontoideum is a separate ossicle with smooth, corticated margins, unlike an acute fracture.
• Rotation on the peg view can make the C1 lateral masses look asymmetrical.
• Degenerative change (osteophytes, disc narrowing, degenerative listhesis) can mask or mimic injury. Compare with old films.
• Ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis (DISH): the rigid spine fractures like a long bone after minor trauma, often through the disc space, and these fractures are highly unstable and easily missed on plain film. CT (and often MRI) is needed. See inflammatory arthritis.
• Rheumatoid arthritis can cause atlanto-axial subluxation without acute trauma.
• Non-contiguous fractures: once you find one spinal fracture, look for another elsewhere. See thoracolumbar spine fractures.

Red flags: act now

What to focus on, by role

Role	Priorities
Medical student	ABCS, adequacy to T1, the four lines, and the fact that adults in the UK usually go to CT first.
Nurse	Spinal precautions and local immobilisation policy. Escalate new neurological symptoms immediately.
Junior doctor	Apply the Canadian C-spine rule, request the right test according to NICE NG232, and never accept a film that does not reach T1.
Radiographer	Swimmer's view technique, a peg view without rotation, and not moving the patient unnecessarily.
Advanced / FRCR	Craniocervical junction measurements, teardrop types, facet injuries, the rigid spine and paediatric variants.

Practise on real spine X-rays →

References

1. NICE NG232. Head injury: assessment and early management (includes cervical spine imaging). nice.org.uk
2. Stiell IG, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA 2001;286:1841–8. jamanetwork.com
3. Hoffman JR, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma (NEXUS). N Engl J Med 2000;343:94–9.
4. Radiology Masterclass. Cervical spine trauma X-ray tutorial. radiologymasterclass.co.uk
5. Radiopaedia. Odontoid process fracture. radiopaedia.org
6. Royal College of Radiologists. iRefer. irefer.org.uk

For education only. Not a substitute for a formal report, senior review or your local policy. Never use this page to make decisions about a real patient.