Disclosure 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. History of the Procedure: Spinal injuries with resulting paralysis have been recognized since the writings of the Edwin Smith papyrus as "an ailment not to be treated." Various authors in the twentieth century 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. 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. More recently, 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. Problem: 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. Etiology: The most frequent causes of spinal column injuries are motor vehicle accidents (45%), falls from heights (20%), sports-related injuries (15%), and acts of violence (15%). Pathophysiology: 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. Clinical: These patients 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.
Relevant Anatomy: 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. Contraindications: 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 Coumadin 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. |
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Medical therapy: Fracture dislocations are associated with the highest incidence of neurologic injury. In those individuals with incomplete or normal neurologic examination findings, the spinal injury has still resulted in significant instability. To allow for early mobilization and the chance for neurologic improvement, surgical management is almost always indicated. Closed reduction of these injuries is quite difficult, if not impossible. Maintenance of the reduction without operative intervention is problematic. Surgical therapy: Most often, dislocation fractures can be managed using an entirely posterior approach. Reduction of the malalignment results in spinal canal clearance in most individuals. Significant residual compression can be addressed through an anterior approach in a staged manner or on the same day, depending on the circumstances. The posterior instrumentation and fusion allow for reestablishing the tension-band function of this segment of the spine; however, if significant anterior column loss (burst component) exists, then anterior reconstruction may be indicated. Daniaux described use of transpedicular bone grafting. In this way, the defect created by the reduction can be filled with autologous bone. The graft is intended to fill the anterior half of the body and to avoid posterior extravasation. Arnold has suggested a second means of posterior grafting, through a basal osteotomy of the transverse process and filling the body through a posterolateral window. Preoperative details: The patient's blood is usually typed and crossmatched, and 2 units of blood are made available preoperatively. Neuromonitoring would be warranted in the unusual case of a patient who is neurologically intact. The anesthesiologist may place an arterial line or may establish central access, depending on the individual patient and other injuries. A Foley catheter is inserted to monitor urinary output throughout the procedure. The patient is placed prone on the operative table, and chest rolls or a Wilson frame may be used after careful logrolling. All bony prominences are padded carefully, and superficial nerves such as the ulnar nerve are protected. The arms are placed on arm boards, and hyperabduction of the shoulders should be avoided. Intraoperative details: A midline incision extending one level above to one level below the proposed segments to be instrumented should be used. Once the incision has been carried down to the tips of the spinous processes, careful subperiosteal dissection should be continued bilaterally to the facet joints. Frequently, much of the dissection has occurred from the injury, with muscle and soft tissues displaced from the bony elements. A good rule is to start above and below in normal anatomy and work carefully towards the injured zone. Packing with gauze sponges helps to tamponade the bleeding, and packing can be replaced as the exposure continues. The transverse processes are then stripped of overlying muscle until the tips are exposed. Bipolar and unipolar cauteries are used to maintain hemostasis. Because the spinal canal may be open and the dura exposed, care must be taken when approaching this area. The exposed facet joints at the level of dislocation may be denuded of their articular cartilage prior to reduction. Frequently, an associated fracture is present. Resection of bone should be avoided at the joint level as this further destabilizes the spine. Reduction is generally achieved by gentle distraction with a lamina spreader and manipulation with bone-holding forceps or towel clips. Once the reduction has been obtained, a single wire or cable may be passed through the adjacent spinous processes prior to definitive fixation. At this point, options for fixation include multiple hooks in a claw construct 2-3 levels above and 1-2 levels below. Depending on the individual anatomy, pedicle screw fixation may be used from 2 segments above to 1-2 segments below. The landmarks for insertion for pedicle screws in the lumbar spine include bisection of the transverse process as it abuts the superior articular facet. The angle of inclination varies from 10-15° at L1 to 25° at L5. Thoracic screw insertion is 3 mm lateral to the center of the facet joint just below the articulation. Image intensification, in addition to surface landmarks, may be used in the thoracic region. Intraoperative stereotaxic guidance has been used in a number of centers but has not been universally applied. While a compression construct provides the most rigid stabilization, the risk of disk herniation increases, and this construct should be used with caution in the patient who is neurologically intact or not. An autograft may then be harvested from the iliac crest, and decortication for fusion purposes generally is performed for the length of the instrumentation. Studies have demonstrated that instrumented segments not formally fused usually undergo ankylosis, and application of the graft may be limited to a segment above the disruption to a segment below. Closure is performed in a layered fashion over a Hemovac drain, which is removed 1-2 days postoperatively. Postoperative details: Postoperatively, the patient should be turned frequently, and thromboembolic prophylaxis should be addressed with compression devices and, in certain instances, medically with either low molecular weight heparin or Coumadin. In certain cases in which anticoagulation therapy is contraindicated (gastrointestinal ulcers, intracranial injuries) or pulmonary embolism has occurred despite adequate anticoagulation, mechanical vena cava filters may be inserted. Early mobilization is encouraged, and, depending on the stability obtained during surgery, bracing may not be necessary. In the patient who is neurologically intact, close monitoring and early mobilization should minimize skin breakdown. The Foley catheter should be removed, and intermittent catheterization should be performed as soon as the patient's general medical condition allows. An early bowel regimen should be initiated, and alternate day suppositories should be used. Once medically stable, transfer to a rehabilitation facility with special expertise in spinal injuries is beneficial to the recovery process. In such a facility, the physical and psychological issues facing the individual patient and the family can be addressed in an environment with others with similar problems. Follow-up care: The sutures generally can be removed after approximately 10 days, and rehabilitation can be initiated as soon as the general medical condition of the patient allows. Arthrodesis progresses over a 3- to 6-month period, and serial radiographs should be obtained to assess alignment and progressive union of the bone grafting. It is not uncommon to see gradual loss of 10° of correction with posterior only procedures. Bracing, which usually is a removable thoracolumbosacral orthosis, is used for 3-6 months. In individuals who are paraplegic, close attention to skin pressure and breakdown must be observed.
Complications can be subdivided into 2 major groups: those related to the operative procedure and those secondary to the spinal cord or cauda equina injuries. Surgical complications can be further classified as related to positioning, intraoperative occurrences, and postoperative complications. Patients with spinal injuries should be positioned carefully at the time of surgery to avoid compression of bony prominences. The arms should be placed at right angles to the body or tucked by the sides. The ulnar nerve is particularly vulnerable, and pressure at the elbow should be avoided. Intraoperative complications include dural tears, misdirected instrumentation, excessive bleeding requiring transfusions, and fluid replacement. While the level of injury is usually obvious at the time of surgery, intraoperative imaging can be extremely valuable to document the levels of stabilization and position of pedicle screws and hooks. Placement of hooks in the thoracic region may compromise canal space, and, if possible, a staggered hook construct avoids excessive canal stenosis at each level. With close attention to position of pedicle screws, malplacement can be avoided. The tip of the screw should not cross the midline on an AP radiograph but generally should point toward the midline. Postoperative attention to adequate resuscitation is of utmost importance. Frequently, fluid and electrolyte concerns, including serum magnesium replacement, must be addressed. Correction of clotting abnormalities may require the administration of fresh frozen plasma and platelets; however, mild deficits usually correct rapidly in the absence of significant liver abnormalities. Postoperative hematomas may require drainage, and persistent drainage should be aggressively managed to avoid an underlying deep infection. The appearance of the skin may be misleading, and, certainly if a spiking temperature occurs in this setting, early exploration is warranted. Unrecognized cerebrospinal fluid leakage may be heralded by postural headaches and clear drainage from the wound. Eismont has suggested open operative repair when possible, but closed drainage techniques for 3-5 days also have been recommended to manage this problem.
Incomplete injuries at the cauda equina level tend to have a more favorable recovery rate compared to mixed conus and cauda equina lesions or lower spinal cord injury. According to a multicenter study reported by Gertzbein, the prognosis for bowel and bladder recovery appears to be improved with anterior decompression. Complete neurologic deficits continue to have a grim prospect for recovery, and emphasis on rehabilitation and incorporation of the individual with paraplegia into society is aided by regional spinal cord injury centers. Long-term management of bowel and bladder dysfunction should include the use of stool softeners, suppositories, a high fiber diet, and intermittent urinary catheterizations to decrease the residual urine volume. Despite these efforts, chronic urinary tract infections continue to plague the patient with paraplegia. The ultimate functional outcome may be affected significantly by the patient's age, body habitus, general medical condition, and cognitive and motivational factors. Depression is quite frequent in this patient population and can adversely affect the recovery and rehabilitative process. A multidisciplinary approach, including physical and occupational therapists as well as psychological support, is desirable. With motor grade strength improvement greater than a 3 (antigravity level), ambulation may be possible with the use of adjunctive orthoses. This may result in extreme energy requirements and may interfere with the performance of upper extremity activities while standing. Simplification of daily routines can help in conserving energy and improving the lifestyles of patients with spinal injuries.
Spinal cord injury continues to be a significant source of morbidity and mortality among the young adult population in this country. 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. Treatment methods have evolved over the last 50 years, and means to minimize the extent of injury are employed. This has included the acute administration of high-dose steroids based on the results of 3 studies published by the National Acute Spinal Cord Injury Study (NASCIS) and the use of gangliosides as reported by Geisler et al. Timely canal decompression and stabilization of the affected areas have been made possible by the introduction of modern instrumentation systems and improved surgical approaches. Research continues to address spinal cord recovery and has included laboratory experiments in neural element transplantation and fetal cell transplants. Firm supportive data for these efforts remain to be clinically proven; however, research must continue in order to aid this growing population of patients.
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