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Despite the protective functions of the discs, ligaments, and muscles, the
spine is subject to traumatic injuries like any other area of the skeletal system,
but the pattern of fractures are unique to the spine. Accurate fracture classification
is a key factor in determining the appropriate treatment for spinal fractures.
(46) The three-column concept is often utilized in describing fracture pattern
in the spine (Figure 8). (47)
Figure 8.
Three-column concept of the spine.
The anterior column consists of the anterior longitudinal ligament and the
anterior one half of the body, disc, and annulus. The middle column consists
of the posterior one half of the body, disc, and annulus, and the posterior
longitudinal ligament. The posterior column consists of the facet joints, ligamentum
flavum, the posterior elements, and the interconnecting ligaments. In the thoracic
spine, a fourth column has been proposed, which consists of the sternum-rib
complex. (48)
Compression fractures involve wedging of the anterior portion of the vertebral
body, most often as a result of vertical force (Figure 9). The middle column
remains intact.
Figure 9.
Lateral radiograph of a patient with a Compression Fracture.
Burst fractures are comminuted fractures of the vertebral bodies often associated
with bone fragments in the canal (Figure 10). Burst fractures involve the anterior
and middle columns. Usually the result of vertical loading and high energy impact,
they are also frequently associated with neurologic deficit.
Figure 10.
Axial CT of a patient with a Thoracic Burst Fracture.
Fracture-dislocation injuries of the spine include any combination of fractures
with dislocation. These types of spinal fractures involve all three columns,
and are usually the result of compression, tension, shear, or rotation. Variants
of fracture-dislocation injuries include:
(a) Anterior/posterior dislocation of the vertebral body with fracture of
bony parts,
(b) Comminuted fractures of the vertebral body with anterior/posterior displacement
and rotation (with tearing of ligaments), and
(c) Lateral dislocation of vertebrae with fracture. All have potentially
devastating neurologic consequences.
Flexion-distraction fractures are usually the result of forceful forward flexion
of the spine, which may occur in motor vehicle crashes where the victim is restrained
by a lap belt only. The tensional forces can disrupt the middle and posterior
columns. A variant of flexion-distraction injury is the Chance fracture, resulting
from hyperflexion of the spine. All three columns fail under tensile forces
in a Chance fracture. The fracture extends through the vertebral body, pedicle,
lamina, and spinous process (Figure 11). The posterior ligaments are disrupted,
and the intervertebral disc and facet joints may also be distracted. (49)
Figure 11.
Sagittal CT reconstruction of a patient with a thoracic Chance Fracture. Note the split pedicle.
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