Lower Cervical Spine Injury

Fig. 1
Compressive flexion (CF) injuries are divided into five stages. The injury is speculated to occur first by flexion of the spine through the facet joints. The anterior column (vertebral body) becomes increasingly compressed and shortened. Eventually, the PLC fails, noted by interspinous gapping and local kyphosis. With further energy, the facet joints will fail, leading to translational deformity.

(A) CF Stage I: Blunting of the anterosuperior vertebral body margin.

(B) CF Stage II: Beak-appearance of the anterosuperior vertebral body margin, a sagittal vertebral body split may also be present.

(C) CF Stage III: Oblique primary fracture line that extends from the anterior vertebral body to the inferior endplate (This has been subsequently described by other authors as a so-called tear-drop fracture.).

(D) CF Stage IV: In addition to stage 3 features, posterior translation of the upper vertebra measuring less than 3 mm.

(E) CF Stage V: Posterior translation of the upper vertebral measuring 3 mm or greater, facet gapping, indicating anterior and posterior ligamentous injury.

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Fig. 2
Anterior subluxation of C5 with wedge compression fracture of C6.

(A, B) Lateral radiographs of the cervical spine show incongruity and lack of parallelism of the C5-6 facets (white lines in B), exposure of the superior facet joint surface of C6, and widening of the interspinous distance at C5-6 ("fanning") (white arrow in B) relative to adjacent levels. Note the subtle localized hyperkyphotic angulation at C5-6 (white lines in A). There is loss of anterior stature of the body of C6 secondary to the compression fracture involving its superior end plate (black line in B).

(C, D) AP radiographs of the cervical spine. On the frontal projection the C5-6 interspinous space is abnormally wide (white arrow in D). This represents the "fanning" seen on the lateral radiograph.

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Fig. 3
Vertical compressive (VC) lesions are thought to arise from primarily axial loads to the cervical spine. The final stage of the injury may result from flexion or extension vectors, which ultimately produce posterior or anterior ligamentous injury, respectively.

(A) VC Stage I: Central superior or inferior endplate fracture.

(B) VC Stage II: Superior and inferior endplate fractures, sometimes with vertebral body fracture lines that give the appearance of a quadrangular fracture fragment.

(C) VC Stage III: Vertebral body comminution, with or without retropulsion of fragments (This has been by others as a burst-type cervical fracture), with or without kyphotic (late flexion type) or translational (late extension type) deformity.

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Fig. 4
Burst (dispersion, axial loading) fracture of C5. Lateral radiograph (A) and sagittal multiplanar reformation (B) demonstrate fractures of each end plate (white arrows) with both anterior and posterior displacement of fracture fragments (black arrows), the latter into the central spinal canal. Note the typical straight alignment of the cervical spine in patients with burst fractures.

(C) Coronal multiplanar CT reformation shows vertical fracture lines extending through the midportion of the vertebral bodies of C5 and C6 with widening of suprajacent (white line) and narrowing of subjacent uncovertebral joints (black line) secondary to lateral displacement of hemivertebral fracture fragments (white double-headed arrow).

(D, E) Axial CT images demonstrate a comminuted fracture of the vertebral body with fragment dispersion; there is a vertical body fracture (white arrows), fragment retropulsion into the spinal canal, and bilateral fractures at the junctions of the laminae and articular masses (black arrows).

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Fig. 5
Distractive flexion (DF) injuries are thought to occur from primarily flexion injury vectors that rotate about an axis anterior to the vertebral body. Thus, distraction and failure of the posterior ligaments can occur without significant vertebral body fracture. In this injury group, increasingly higher stages does not always correspond to increasing amount of instability.

(A) DF Stage I: Facet subluxation, gapping of the spinous process ligaments, indicating failure of the PLC, with or without some blunting of anterosuperior vertebral body (like CF stage I).

(B) DF Stage II: Unilateral facet dislocation, usually PLC is intact, rotational deformity.

(C) DF Stage III: Bilateral facet dislocations, 50% translation of upper vertebral body on lower one.

(D) DF Stage IV: Close to 100% translation of upper vertebral body on lower one, apperance of a so-called floating vertebra.

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Fig. 6
Anterior vertebral translation in different flexion injuries. The amount of anterior translation with unilateral dislocation (B) is less than occurs with bilateral facet dislocation (C) but greater than that of anterior subluxation (A).

(A) In anterior subluxation the involved vertebra may be displaced slightly anteriorly (1 to 3 mm), <25% of the AP diameter of the subjacent vertebral body.

(B) Unilateral facet dislocation demonstrating anterior translation of the dislocated vertebra 25% to 50% of the AP diameter of the subjacent vertebral body.

(C) Bilateral facet dislocation with anterior displacement of the involved vertebra >50% of the anteroposterior diameter of the subjacent vertebral body.

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Fig. 7
"Bowtie" and "laminar space" (114) signs in unilateral facet dislocation of C4-5.

(A, B) Lateral cervical spine radiographs show anterolisthesis of C4-5 with about 25% displacement. The articular pillars are offset from C4 above (white lines in B) and are seen in oblique profile giving the "bowtie" appearance; the "bowtie" sign indicates rotation. The articular pillars are superimposed at C5 and below and are seen in lateral profile (black lines in B).

(C, D) Lateral cervical spine radiographs. The laminar space is the distance between the spinolaminar line and the posterior surface of the articular pillars. The laminar space changes abruptly between C4 and C5, with the laminar space reduced above the C5 level (compare the black lines and white lines in D indicating sudden rotation).

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Fig. 8
Compressive extension (CE) injuries are divided into five stages. They are postulated to start with compression of the posterior elements without failure of the anterior ligaments. Further injury leads to failure of the anterior/posterior ligaments.

(A) CE Stage I: Posterior arch fracture that may be facet, pedicle, or lamina fracture, with or without rotation that can result in mild anterior translation. (These are more commonly referred to as lateral mass fractures.)

(B) CE Stage II: Bilateral lamina fractures, can be multiple levels.

(C) CE Stage III: Bilateral lamina, facet, pedicle fractures without vertebral body displacement. Although admittedly "hypothetical… having not been encountered" in their review, the injury may be described as a floating lateral mass fracture.

(D) CE Stage IV: As for CF stage III, with partial anterior vertebral body displacement.

(E) CE Stage V: As for CF stage III, with 100% anterior vertebral body displacement.

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Fig. 9
Hyperextension comminuted laminar and spinous processes fractures. Cervical spine injuries caused by hyperextension are characterized by distraction of the anterior and middle columns and compression of the posterior column (A). Lateral radiograph demonstrates posterior impaction with multiple comminuted laminar and spinous processes fractures from C2 to C6 (white arrows). The acute vacuum disc (black arrow) with abnormal widening of the anterior C6-7 disc space is a sign of anterior and middle column distraction.

(B, C) Axial CT images demonstrate displacement of the spinous processes and bilateral comminuted laminar fractures (white arrows).

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Fig. 10
Distractive extension (DE) injuries, like DF injuries, demonstrate substantial ligamentous injury in lower stages. Initial failure is through the anterior ligaments.

(A) DE Stage I: Abnormal widening of the disc space, may or may not be avulsion fractures of the anterior vertebral body margin, no posterior translation.

(B) DE Stage II: DF stage I plus posterior translation.

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Fig. 11
Normal prevertebral soft tissues. Normal lateral radiographs (A, B). The prevertebral soft tissue is normal in thickness (white lines, C3 <5 mm and C6 <22 mm) and contour (black line). Note slight convex bulge anterior to C1 anterior tubercle (white arrow) and concavity caudal and rostral to the tubercle (curved arrows). At the cervicothoracic level the soft tissue shadow contour (black arrow) is normally near parallel to the arc formed by the anterior cortices of the lower cervical and upper thoracic vertebral bodies.

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Fig. 12
Lateral radiograph (A) and sagittal CT multiplanar reformation (B) of a normal cervical spine. The vertebrae are aligned in a gentle lordotic configuration. The lines connecting the anterior margin of the vertebral bodies (1), the posterior cortical margins of the vertebral bodies (2), and the anterior margins of the junctions of the spinous processes and laminae (spinolaminar line) (3) should form three parallel gentle convex curves with no steps or discontinuities. The spacing between these lines is uniform.

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Fig. 13
Flexion teardrop fracture of C5. Lateral radiographs (A, B) of the cervical spine show typical flexion teardrop fracture with anteriorly displaced triangular fracture fragment ("teardrop") of the anterior-inferior aspect of vertebral body of C5 (white arrow in B) and retropulsion of its posterior vertebral body fragment into spinal canal (black arrow in B). Note a subtle localized kyphotic angulation at C5-6 and widening of the interspinous distance at C5-6 ("fanning") (white double arrow in B).

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Fig. 14
C5-6 unilateral facet joint dislocation. Lateral radiographs (A) of the cervical spine show unilateral facet joint dislocation. Lateral radiographs (B) of the 2 years after operation (ACDF) show well reduction and fixation state.

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Fig. 15
C3-4 unilateral facet joint dislocation. Lateral radiographs (A) of the cervical spine show unilateral facet joint dislocation. Lateral radiographs (B) of the 3 years after operation (posterior wiring) show well reduction and fixation state.

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Fig. 16
Bursting fracture of T1 and C7-T1 unilateral facet joint dislocation. Lateral radiographs (A) of the cervical spine show anterior wedging fracture of T1 and C7-T1 unilateral facet joint dislocation. Lateral radiographs (B) of the 6 months after operation (ACDF and posterior fusion with lateral mass screw) show well reduction and fixation state.

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