Laboratory Studies
The laboratory workup for spinal dislocation parallels that for any patient with complex traumatic injuries and should routinely include the following:
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Complete blood count (CBC)
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Comprehensive metabolic profile
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Urinalysis
The workup frequently also includes clotting studies (prothrombin time [PT] and activated partial thromboplastin time [aPTT]).
If the patient presents in shock, urgent type and crossmatch is necessary for blood administration. Given that a dislocation fracture requires a significant insult, associated chest and abdominal injuries are not uncommon.
Imaging Studies
Plain radiography
Imaging for spinal dislocation begins with high-quality plain radiographs taken in the anteropoesterior (AP) and lateral views. [12] These most often demonstrate the severity of the injury. A well-centered lateral view provides information on alignment and associated fractures, primarily of the anterior column. The AP view demonstrates associated injuries to the ribs and transverse processes, which are an indication of the violent nature of the injury. Associated pneumothorax may also be demonstrated from this view. (See the images below.)
Computed tomography
Computed tomography (CT) supplements the information gathered from plain radiography and provides pertinent data on the injuries to the posterior elements, including lamina and facet injuries. The empty facet sign is a complete dislocation of these joints and is a hallmark finding with these injuries as well as severe flexion-distraction–type traumas. These studies usually are obtained with 3-mm cuts and can be reformatted in the frontal and sagittal planes. [13]
Magnetic resonance imaging
Magnetic resonance imaging (MRI) is infrequently required; plain radiographs and CT scans can provide most of the data needed to treat these injuries. If the neurologic examination findings do not correlate with the level of injury determined from plain films, then MRI may be indicated to provide additional information on adjacent levels of involvement. The neural elements and disk injuries are better depicted by MRI. [14, 13]
Ultrasonography
In some centers, ultrasonography has been used intraoperatively to assess canal clearance. Specific expertise in the interpretation of these intraoperative ultrasonograms is required and is not always available.
Classification
Many classification systems for thoracolumbar fractures exist. None are universally accepted, but each has its own merits and limitations. Important factors in the application of any classification system include simplicity, reproducibility, and the ability to assist in making management decisions. [15, 16, 17]
Historically, Holdsworth viewed the spine as a two-column structure, with the vertebrae representing the anterior loadbearing column and the posterior elements (pedicles, laminae, spinous processes, and attaching ligaments) functioning primarily as a tension band resisting tensile loads. Involvement of either structure or both structures, according to Holdsworth, necessitated potentially different modes of reconstruction. [18]
Currently, the AO classification has many advocates.
Magerl basically divided thoracolumbar fractures into the following three groups [19] :
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Group A involves compression injuries
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Group B involves distraction mechanisms
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Group C involves torsional injuries
Further subdivisions are based on the morphology of the fracture and its associated ligamentous components. This system and others base their classification on findings from plain radiographs and CT scans. Although it is extremely inclusive and comprehensive, interobserver agreement appears to be no greater than 67%. [15]
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Flexion distraction injury with facet dislocation.
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Fracture dislocation.
