Subaxial cervical injuries (C3–C7)

From C3 to C7 the cervical spine fails in three basic ways: the vertebral body is crushed (A), the posterior or anterior tension band is torn (B), or one vertebra translates on the next (C), typically as a facet dislocation. C5–C7 are most often affected. Every injury is graded together with the neurological status and the facets.

Mechanism

Flexion with axial load (diving, rugby, rollover crashes): compression, burst and teardrop fractures. Flexion–distraction and rotation: facet subluxation and dislocation. Hyperextension: anterior tension band failure, especially in the stiff spine (ankylosing spondylitis, DISH) and in the elderly with spondylosis (central cord syndrome).

Clinical findings

• Spinal motion restriction; assess with the Canadian C-spine rule or NEXUS criteria. ATLS primary survey; neurogenic shock (hypotension with bradycardia) differs from haemorrhagic shock.
• Full ISNCSCI/ASIA examination including sacral sparing (perianal sensation, voluntary anal contraction); priapism suggests cord injury.
• A stiff, ankylosed spine fractures with trivial trauma and is highly unstable: image the whole spine and keep the patient in their usual posture.

Imaging

• CT occiput to T1 (radiographs only if CT is unavailable; the lateral must show the C7–T1 junction).
• MRI for any neurological deficit, suspected disc or ligament injury, or before open reduction in a patient who cannot be examined.
• CT angiography for fractures through a transverse foramen, facet dislocations or posterior circulation symptoms.

• CT from occiput to T1 is the first test in adults; radiographs only if CT is unavailable.
• MRI for any neurological deficit, before open reduction of a dislocation in a patient who cannot be examined, and when ligament or disc injury is suspected.
• Facet dislocation: unilateral gives about 25% anterior translation with rotation, bilateral about 50%. Look for the "naked facet" on axial CT.
• CT angiography for fractures through the transverse foramen and facet dislocations (vertebral artery injury).

Classification

A0–A4

Compression injuries: A0 minor (spinous or transverse process), A1 one endplate, A2 coronal split or pincer, A3 burst with one endplate, A4 burst with both endplates or split with posterior wall.

B1–B3

Tension band injuries: B1 posterior bony, B2 posterior capsuloligamentous or bony-ligamentous, B3 anterior (hyperextension, through the disc or body).

C

Translation of one vertebra on another in any plane, including facet dislocations.

F1–F4

Facet modifiers: F1 non-displaced facet fracture, F2 facet fracture with potential instability, F3 floating lateral mass, F4 subluxed, perched or dislocated facet (BL = bilateral).

N, M

Neurology N0–N4 (and NX); case modifiers M1 posterior ligament injury without complete disruption, M2 critical disc herniation, M3 stiff or metabolic bone disease, M4 vertebral artery abnormality.

Types shown in 3D

A1 wedge (C5)

Compression of the upper endplate with an intact posterior wall and tension band. Stable: collar.

A4 burst (C5)

Both endplates and the posterior wall fail; a fragment of the posterior wall is pushed back into the narrow cervical canal. Anterior corpectomy and fusion if the cord is compressed.

B2 posterior tension band (C5–C6)

Flexion–distraction tears the facet capsules, ligamentum flavum and interspinous ligaments: the spinous processes fan apart, the facets are subluxed but not dislocated. Posterior fixation.

C bilateral facet dislocation (C5–C6)

C5 has translated forwards by about half a vertebral body: both inferior facets of C5 are locked in front of the superior facets of C6. High rate of complete cord injury.

C unilateral facet dislocation (F4)

Flexion with rotation: one facet jumps and locks, giving about 25% forward slip with rotation of C5 on C6. Often a root deficit rather than cord injury.

Treatment

Stable (A0–A2, minor F1)

Rigid collar 6–12 weeks, upright radiographs to confirm alignment.

Burst and teardrop with cord compression

Anterior corpectomy and fusion with plate (posterior fixation added for posterior ligament injury). Early decompression (within 24 h) is advised for acute cord injury; keep mean arterial pressure at least 75–80 mmHg (upper target 90–95) for 3–7 days; many centres still aim for 85–90.

Facet dislocation (C, F4)

Awake, cooperative and examinable patient: closed reduction with skull tongs and incremental weights under serial neurological examination. Otherwise, or if closed reduction fails, MRI first; if a herniated disc is found, anterior discectomy before reduction. Fusion afterwards, anterior or posterior.

Tension band injuries (B)

Usually surgical: posterior lateral mass screws for B1–B2; long posterior fixation for B3 injuries in an ankylosed spine.

Aftercare

Collar after anterior fusion for comfort; rehabilitation in a spinal cord unit for any cord injury. Watch for dysphagia and hoarseness (recurrent laryngeal nerve) after anterior surgery.

Complications

• Neurological deterioration (missed instability, reduction against a disc herniation)
• Vertebral artery injury and posterior circulation stroke
• Adjacent segment degeneration after fusion
• Complications of cord injury: pneumonia, pressure sores, thromboembolism, autonomic dysreflexia