Spinal Dislocations 

The unique anatomy of the thoracolumbar junction predisposes this level of the spinal column to dislocation fractures. As the thoracic spine loses its structural rigidity with floating ribs at T11 and T12, the orientation of the facet joints also changes from a more frontal projection to oblique and then sagittal in the upper lumbar spine. These spinal dislocation fractures result from violent traumatic injuries and are associated with a very high incidence of neurologic deficit resulting from the translation of the spine.

Approximately 90% of dislocations above T10 result in complete paraplegia, and 60% of dislocations below T10 result in complete neurologic deficit. The spinal cord ends at the L1-2 level in most adults; the cauda equina represents the terminal nerve roots of the lumbosacral spine present below this site. The prognosis for a pure nerve root injury is much better than for an actual spinal cord injury. In some of these injuries, spinal cord injury and nerve root damage are combined.

Spinal injuries with resulting paralysis have been recognized since the writings of the Edwin Smith papyrus as "an ailment not to be treated."^{[1, 2]} Various authors have proposed postural reduction on frames with prolonged bedrest as a means of achieving spinal stability. Nicoll favored early return of function regardless of nonanatomic alignment of the spine.^[3]

None of these early series provide techniques to reduce and stabilize the thoracolumbar spine; however, these techniques are available to contemporary surgeons. With the advent and use of Harrington rod instrumentation, a debate arose about nonoperative versus operative care for these highly unstable injuries. Fixation devices have been devised that allow fewer segments to be incorporated in the surgical construct. While the posterior approach is used most often, anterior procedures also may be important in reconstruction after these devastating injuries. The surgical approach allows for earlier mobilization, minimizing medical complications and preventing progressive deformity.

Of the injuries affecting this region of the spine, dislocation fractures of the thoracolumbar spine are the most unstable, secondary to the soft tissue and bony disruption from the high-energy mechanics of injury. This injury is associated with the highest incidence of neurologic deficits and chest and abdominal trauma. Involvement of all 3 spinal columns generally requires operative intervention to stabilize the spine and optimize neurologic recovery and patient rehabilitation.

Frequency

Each year approximately 10,000 new patients with spinal cord injuries are added to the 180,000-200,000 individuals already living with spinal cord injuries.

The most frequent causes of spinal column injuries are motor vehicle accidents (45%), falls from heights (20%), sports-related injuries (15%),^[4] and acts of violence (15%).^[5]

Dislocation fractures of the thoracolumbar junction involve disruption of all 3 spinal columns resulting from a combination of mechanisms, including compression, tension, rotation, and shear injury. While the shear component may occur from anterior to posterior, it more frequently is recognized from posterior to anterior with sequential failure of the posterior ligamentous complex, fracture of the lamina, buttressing of the facet joints, and, finally, anterior vertebral body compression. The rotational insults are recognized by the fractures of the transverse processes and adjacent lower ribs. The fracture through the lamina frequently results in dural tears and entrapped nerve roots. This may have a bearing on the initial surgical approach to reconstruction of the spine.^{[6, 7, 8]}

Patients with spinal injuries should be questioned about any transient paralysis or paresthesias involving the lower extremities. The history of the accident should include attention to mechanisms, including whether the patient was the driver or the passenger, whether the patient was restrained or unrestrained, what the rate of speed of the vehicle was, what distance the patient fell (for injuries from falls from heights), or what weights were applied to the spine at the time of injury. If the patient is unable to relate the history, it may be obtained from emergency medical personnel on the scene or other witnesses.

The physical examination should initially include attention to the details relevant for all traumatized patients (ie, the ABCs [patent airway, spontaneous breathing, stable circulation], blood pressure, and pulse). In the spinal examination, specific attention should be paid to direct palpation for tenderness, deformity, or defects. The unique finding in thoracolumbar dislocations is that of a fixed gibbus deformity at the level of injury. The patient is most appropriately placed in the lateral decubitus position with the knees flexed if any neurologic compromise is present. This maximizes the residual diameter of the narrowed spinal canal.

A thorough neurologic examination should include graded motor function of the major muscles in the lower extremity (0-5), sensory examination to both sharp and dull stimuli, and reflex evaluation. In addition to the tendon reflexes, the bulbocavernosus and cremasteric reflexes and the perianal wink should be recorded. A rectal examination documenting the status of the patient's rectal tone must be routinely performed. Dermatomes can be assessed quickly, and landmarks, such as the umbilicus (T10), anterior knee (L3), dorsolateral foot (S1), and perianal region (S3,4,5), can be used. Usually, an indwelling catheter is inserted into the bladder, and urine output is monitored.

The usual indications for surgical reconstruction include loss of mechanical stability and neurologic compromise. With the high incidence of neurologic deficits associated with dislocation fractures, surgical management remains a primary tool for the recovery of these patients. Since all 3 columns of the spine are involved, reconstruction may include an anterior or posterior approach. Not infrequently, both approaches may be necessary to maximize neurologic recovery and to reestablish spinal column integrity. If the neurologic deficit is complete with return of reflex function, recovery is unlikely, and surgery is performed to expedite rehabilitation. When the injury results in an incomplete deficit that is progressing, urgent decompression and stabilization are indicated to halt progressive neurologic loss and to hasten recovery.

The thoracolumbar junction represents a region of the spine in which the relatively rigid thoracic area transitions to the more mobile lumbar spine, based on anatomic changes in the vertebral body, facet joints, and adjacent ribs.

The anterior column of the spine in this area consists of the vertebral bodies and their superior and inferior disks. The bodies increase in size in both anteroposterior (AP) and medial and lateral planes. The disk heights also increase, allowing more motion.

The posterior column, which acts as a tension band, consists of the pedicles, facet joints, lamina, and transverse and spinous processes. Ligamentous structures add stability and are most effective in resisting loads in the planes in which the fibers run. They tighten under tension and buckle under compression. These include the anterior and posterior longitudinal ligaments (which attach to the vertebral bodies and disks) anteriorly and the intertransverse, capsular, interspinous, and supraspinous ligaments posteriorly.

The ligamentum flavum attaches to anterior-inferior border of the laminae above to the posterior-superior border of the laminae below. These ligaments tend to be thicker in the thoracic region and have a midline cleavage plane throughout. Because of the large amount of elastin present, this tissue is the most elastic tissue in the spine.

The orientation of the facet joints changes from the frontal plane in the thoracic spine to the more oblique plane at the thoracolumbar junction.

Care should be taken in positioning the patient with a thoracolumbar dislocation. It has been demonstrated that supine positioning further narrows an already compromised spinal canal. Turning the patient to a lateral position with the spine slightly flexed may improve function in an incomplete injury. Attempts at closed reduction are usually unsuccessful for these injuries, and operative intervention is necessary for definitive reduction and stabilization.

Contraindications to surgery are few. Surgery is contraindicated in patients on warfarin or other anticoagulants. In these patients, reversal of the anticoagulated state is required prior to surgery. Surgery may be contraindicated in patients with medical conditions such as acute myocardial infarctions.