• INJURIES TO C3–C7

• Vertebral bodies have a superior cortical surface that is concave in the coronal plane and convex in the sagittal plane, allowing for flexion, extension, and lateral tilt by the gliding motion of the facets.

• The uncinate process projects superiorly from the lateral aspect of the vertebral body. With degenerative changes, these may articulate with the superior vertebra, resulting in an uncovertebral joint (of Luschka).

• The mechanism of injury includes motor vehicle accidents, falls, diving accidents, and blunt trauma.

• Radiographic evaluation consists of AP, lateral, and odontoid views of the cervical spine, as described earlier in the section on radiographic evaluation of cervical spine instability.

  • If cervical spine instability is suspected, flexion/extension views may be obtained in a willing, conscious, and cooperative patient without neurologic compromise. A “stretch” test (Panjabi and White) may be performed with longitudinal cervical traction. An abnormal test is indicated by a >1.7-mm interspace separation or a >7.5-degree change between vertebrae.

  • CT scans with reconstructions may be obtained to characterize fracture pattern and degree of canal compromise more clearly.

  • MRI may be undertaken to delineate spinal cord, disc, and canal abnormalities further.

  • The amount of normal cervical motion at each level has been extensively described, and this knowledge can be important in assessing spinal stability after treatment. Flexion-extension motion is greatest at the C4–C5 and C5–C6 segments, averaging about 20 degrees. Axial rotation ranges from 2 to 7 degrees at each of the subaxial motion segments; the majority (45% to 50%) of rotation occurs at the C1–C2 articulation. Lateral flexion is 10 to 11 degrees per level in the upper segments (C2–C5). Lateral motion decreases caudally, with only 2 degrees observed at the cervicothoracic junction.

Classification (A len-Ferguson) (Fig. 9.10)

 

 

 

1. Compressive flexion (shear mechanism resulting in “teardrop” fractures)

   Stage I: Blunting of anterior body; posterior elements intact

   Stage II: “Beaking” of the anterior body; loss of anterior vertebral height

   Stage III: Fracture line passing from anterior body through the inferior subchondral plate

   Stage IV: Inferoposterior margin displaced <3 mm into the neural canal

   Stage V: “Teardrop” fracture; inferoposterior margin >3 mm into the neural canal; failure of the posterior ligaments and the posterior longitudinal ligament

2. Vertical compression (burst fractures) (Fig. 9.11)

   Stage I: Fracture through the superior or inferior endplate with no displacement

   Stage II: Fracture through both endplates with minimal displacement

   Stage III: Burst fracture; displacement of fragments peripherally and into the neural canal

    

    

    

3. Distractive flexion (dislocations) (Fig. 9.12)

   Stage I: Failure of the posterior ligaments, divergence of the spinous processes, and facet subluxation

   Stage II: Unilateral facet dislocation; translation always <50%

   Stage III: Bilateral facet dislocation; translation of 50% and “perched” facets

   Stage IV: Bilateral facet dislocation with 100% translation

    

    

    

4. Compressive extension (Fig. 9.13)

   Stage I: Unilateral vertebral arch fracture

   Stage II: Bilateral laminar fracture without other tissue failure

   Stages III, IV: Theoretic continuum between stages II and V

   Stage V: Bilateral vertebral arch fracture with full vertebral body displacement anteriorly; ligamentous failure at the posterosuperior and anteroinferior margins

    

    

    

5. Distractive extension (Fig. 9.14)

   Stage I: Failure of anterior ligamentous complex or transverse fracture of the body; widening of the disc space and no posterior displacement

   Stage II: Failure of posterior ligament complex and superior displacement of the body into the canal

    

    

    

6. Lateral flexion (Fig. 9.15)

   Stage I: Asymmetric, unilateral compression fracture of the vertebral body plus a vertebral arch fracture on the ipsilateral side without displacement

   Stage II: Displacement of the arch on the AP view or failure of the ligaments on the contralateral side with articular process separation

    

    

    

7. Miscellaneous cervical spine fractures

   • “Clay shoveler’s” fracture: This is an avulsion of the spinous processes of the lower cervical and upper thoracic vertebrae. Historically, this resulted from muscular avulsion during shoveling in unyielding clay with force transmission through the contracted shoulder girdle. Treatment includes restricted motion and symptomatic treatment until clinical improvement or radiographic healing of the spinous process occurs.

   • Sentinel fracture: This fracture occurs through the lamina on either side of the spinous process. A loose posterior element may impinge on the cord. Symptomatic treatment only is indicated unless spinal cord compromise exists.

   • Ankylosing spondylitis: This may result in calcification and ossification of the ligamentous structures of the spine, producing “chalk stick” fractures after trivial injuries. These fractures

     are notoriously unstable because they tend to occur through brittle ligamentous structures. Attempts at reduction, or even repositioning the patient, may result in catastrophic spinal cord injury as the injury involves all three spinal columns. Treatment includes traction with minimal weight in neutral or the presenting position of the neck, with aggressive immobilization with either halo vest or open stabilization.

   • Gunshot injuries: Missile impact against bony elements may cause high-velocity fragmentation frequently associated with gross instability and complete spinal cord injury. Surgical extraction of missile fragments is rarely indicated in the absence of canal compromise. Missiles that traverse the esophagus or pharynx should be removed, with aggressive exposure and debridement of the missile tract. These injuries carry high incidences of abscess formation, osteomyelitis, and mediastinitis.