INTRODUCTION AND EPIDEMIOLOGY
Trauma to the spine can cause a vertebral column injury, a spinal cord injury, or both. A few studies have tried to estimate the annual incidence of specific types of vertebral column injuries in the general population with results ranging from 15 to 65 cases per 100,000,1,2 but no current figures are available for the U.S. population. In contrast, the estimated annual incidence of spinal cord injury in the United States is 54 cases per million or 17,500 new cases per year, with 81% male victims, a mean age of 42 years, and a 63% non-Hispanic white predominance.3 Since 2010, the leading causes of spinal cord injury are vehicular (38%), falls (31%), and violence (13%). Lifetime costs for spinal cord injury victims vary according to age at time of injury, severity of injury, and socioeconomic status; however, estimates range in millions of dollars per patient.3
The vertebral column is composed of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 4 (usually fused) coccygeal. The axial vertebrae (C1 and C2) are anatomically unique in that they are designed for rotary motion. The odontoid (dens) of the axis (C2) is held against the atlas (C1) by the strong transverse ligament. The remaining vertebrae share some common anatomic features (Figure 258-1). A typical subaxial vertebra is composed of an anterior body and a posterior vertebral arch. The vertebral arch is comprised of two pedicles, two laminae, and seven processes (one spinous, two transverse, and four articular). These articulations enable the spine to engage in flexion, extension, lateral flexion, rotation, or circumduction (combination of all movements). The orientation of these articular facet joints changes at different levels of the spine and accounts for variations in motion of specific regions of the vertebral column. Due to its inherent flexibility, the cervical spine is overall the most commonly injured region of the spinal column, with most injuries occurring at the C2 level and from C5 to C7.4 The second most common region of injury is in the thoracolumbar transition zone (T11 to L2). However, these population tendencies can be influenced by mechanism of injury. For example, in one study,5 cervical spine fractures were more common in traffic collisions, whereas falls more commonly resulted in lumbar fractures. Even the type of motor vehicle collision can skew injury patterns, as motorcycle drivers tend to have cervical spine injuries much more commonly than other types of motor vehicle collision victims.6
Vertebral anatomy. Each vertebra consists of a vertebral body and posterior element. Vertebrae are stabilized by an anterior longitudinal ligament, posterior ligament, and interspinous ligament.
A series of ligaments serves to maintain alignment of the spinal column. The anterior and ...