Fractures of the lower cervical spine (C3-C7)

Based on the AO classification system, Aebi introduced a classification system for fractures of the lower cervical spine (C3-C7) that refers to the anterior column (vertebral body and intervertebral disc) and the posterior elements of the vertebra (vertebral joints and ligamentous apparatus).

Type A fractures
are injuries that occur mainly in the anterior column:

A1:     Solely or primarily bony injury
A1.1:  Uniform compression
A1.2:  Marginal fracture without visible ligament injury
A1.3:  Wedge fracture without visible ligament injury

A2:     Osteoligamentous lesion
A2.1:  Vertebral body fracture, multifragmentary, one upper plate affected, 1 intervertebral disc injured
A2.2:  A2.1 + 2 intervertebral discs affected
A2.3:  Fragmented fracture, posterior wall dislocated by less than 3 mm, posterior elements not visibly
          injured

A3:     Solely or primarily ligamentous lesion
A3.1:  Rupture of the anterior longitudinal ligament and intervertebral disc
A3.2:  Traumatic disc hernia

Type B fracture
are injuries that generally occur in the posterior elements:

B1:     Solely or primarily osseous lesion
B1.1:  Isolated fracture of the posterior elements
          (1) Spinous process       
          (2) Arch
          (3) Both
B1.2:  Fracture of the small vertebral joints without dislocation
          (1) Unilateral
          (2) Bilateral
B1.3:  Combination of B1.1 and B1.2
          (1) Spinous process
          (2) Arch
          (3) Both

B2:     Osteoligamentous lesion
B2.1:  Fracture of posterior elements with subluxation
          (1) Spinous process
          (2) Arch
          (3) Both

B2.2:  Facet fracture (shearing) + subluxation of adjacent facets
          (1) Unilateral
          (2) Bilateral
B2.3:  Massa articularis rupture (fracture through pedicle and arch)
          (1) Unilateral
          (2) Bilateral

B3:     Solely or primarily ligamentous lesion
B3.1:  Rupture of the posterior ligamentous complex with subluxation in the vertebral joints (bilateral)
B3.2:  Rupture of the posterior ligamentous complex with asymmetrical subluxation in the vertebral
          joints (unilateral)

Type C fractures
fractures are injuries that affect both the anterior column and the posterior elements:

C1:     Solely or primarily osseous lesion
C1.1:  Burst fracture of the vertebral body in combination with burst fracture of the posterior elements
          (arch, spinous process)
C1.2:  Horizontal fracture through vertebral body with burst of the posterior elements (arch, spinous
          process)

C2:     Osteoligamentous lesion
C2.1:  Luxation fracture with fracture in posterior elements
          (1) Arch and/or processus spinosus
          (2) Facet fracture
C2.2:  Wedge fracture of the vertebra with rupture of the posterior ligament complex
          (1) Osteoligamentous
          (2) Solely ligamentous
C2.3:  Vertebral body fracture (fissure in anterior superior portion + posterior fragment with dislocation
          greater than 3 mm in the spinal canal) (tear drop fracture)
          (1) Osteoligamentous
          (2) Solely ligamentous

C3:     Solely or primarily ligamentous injury
C3.1:  Solely luxation, unilaterally hooked
C3.2:  Solely luxation, bilaterally hooked
C3.3:  Rupture of the disc and dorsal luxation with rupture of the posterior ligamentous complex

• Pain (local, movement-induced, radiating)
• Medullary symptoms with incomplete or complete paraplegia
• Radicular symptoms
• Increased neck circumference due to prevertebral internal hemorrhaging
• Spinal shock
• Specific symptoms of additional secondary injuries

If a cervical vertebra fracture is suspected, an accident victim must be treated with utmost caution. Examination, positioning, and transport must be carried out safety and gently so as not to provoke any worsening of the initial status.

The clinical and neurological examinations provide information on:

• The vertebral height of the injury (reference muscles, reflex status, sensomotor status)
• Medullary or radicular symptoms
• Any secondary injuries

Radiological diagnostics are done with conventional x-ray images of the cervical spine in 2 planes, where the cervical spine should be held under gentle tensile traction.
The most important signs of instability in conventional x-ray images are:

• Segmental sagittal shift
• Expansion of the intervertebral disc space
• Subluxation of the facet joints
• Widening of the prevertebral soft tissue shadow as sign of internal hemorrhaging.
• Bony detachment of the anterior margin of the vertebra close to the base plate (tear drop sign), indicating discoligamentous instability.

Computer tomography with reconstruction images allows for the precise imaging of the destroyed portion of the vertebra. An MRT scan is a good method of obtaining clear images of existing injuries of the spinal cord, spinal nerves, and ligamentous apparatus.

If a cervical vertebra injury is suspected, the patient must be safety immobilized without delay with rigid orthotic devices (e.g. ”stiff neck”) until the diagnosis can be confirmed. The following conditions are absolute surgical indications:

• Complete tetraplegia
• Incomplete paraplegic syndrome
• Fractures with radicular deficits due to root compression
• Unstable fractures without neurological complications

Depending on the initial findings, surgical methods employing either dorsal or ventral access may be used.

• Cloward-Robinson ventral fusion
• Ventral corporectomy and bridging spondylodesis with titanium cage and plate
• Ventrodorsal repositioning spondylodesis with ventral and dorsal instrumentation
• Solely dorsal repositioning and fusion
• Dorsal decompression with dorsally instrumented fusion