Chapter 45: Thoracolumbar Spine Fractures and Dislocations

Christopher K. Kepler, Alexander R. Vaccaro

Chapter Outline

Introduction to Thoracolumbar Spine Fractures and Dislocations

Between 5% and 10% of polytrauma patients suffer spinal fractures or dislocations72,119 with 65% to 80% of these injuries occurring within the thoracic or lumbar regions.72,157 The vast majority of these injuries affect the motion segments between T11 and L2 at the thoracolumbar junction.56 These motion segments connect the relatively rigid, kyphotic thoracic spine, which is stabilized by the rib cage, to the more mobile, lordotic lumbar vertebrae; the differences in mobility between the thoracic and lumbar spine regions cause this transitional zone to experience substantial biomechanical stresses during traumatic incidents, making it more susceptible to fracture. 
Thoracolumbar injuries are usually thought to exhibit a bimodal age distribution, with peaks among males under 40 years of age and again in the 50 to 70 age group which is made up of a higher percentage of females compared to the younger age groups.56,72,157 However with an increasing number of elderly in the population the distribution curve of thoracolumbar fractures has changed from the Type A bimodal curve (Chapter 3, Fig. 3-3) to a Type F curve with a unimodal increase in the elderly population (Chapter 3, Table 3-13). This was confirmed in a recent Swedish study.78 In younger patients, these fractures normally arise from high-energy blunt trauma such as motor vehicle accidents, falls from a height, and sports-related injuries. In particular, motorcycle riders are more likely to sustain severe spinal fractures than are passengers inside an automobile.129 In recent years the incidence of thoracolumbar injuries resulting from gunshot wounds and other projectiles has also been increasing.22 
The elderly are at particular risk of thoracolumbar spinal fractures principally because of poor bone density and declining mental status. Elderly patients typically present after a low-energy mechanism, such as a fall from a standing position, which is the most common mechanism of injury, causing nearly 60% of these injuries in the elderly compared with around 15% in a younger population.78 The incidence of fractures of the thoracic and lumbar spine increases sharply in elderly patients. Jansson et al.78 described an annual incidence, in patients younger than 60 years, of 13 fractures per 100,000 which rose to more than 50 fractures/100,000 in patients above 70 years of age and to above 100 fractures/100,000 for individuals older than 80 years. However it should be remembered that the true incidence of thoracolumbar spinal fractures is difficult to determine as many osteoporotic compression fractures are never diagnosed.37,78 The most common vertebral fracture in the elderly after low-energy mechanisms of injury are compression fractures. Osteoporotic compression fractures are typically stable injuries which can be treated nonoperatively. This accounts for the relatively low rate of surgical intervention in elderly patients with thoracolumbar fractures compared to younger populations (2% in ≥60 years old vs. 15% in <60 years old).78 
Unfortunately, around 20% of patients with thoracolumbar fractures will develop some type of neurologic deficit. This occurs in nearly 1 in every 20,000 individuals living in the United States.45 In addition to the extensive morbidity sustained by these patients, the 1-year mortality rate of patients with paraplegia or other catastrophic thoracic or lumbar spinal cord injuries (SCIs) is approximately 4%.114 Elderly patients are more likely to suffer SCI after spinal fractures for reasons which are not entirely clear but may be related to physiologic differences or coexisting degenerative changes.119 Elderly patients who suffer SCI have worse outcomes than do younger patients; age has been identified as an independent predictor of mortality in elderly patients with SCI.170 Furthermore, the presence of a complete SCI in elderly patients has been identified as a predictor of the need for lifelong institutionalization,64 suggesting that such patients have great difficulty maintaining independence after severe SCI. Although treatment algorithms are identical for elderly patients with thoracolumbar injuries provided the patient is healthy enough to undergo surgery, elderly patients with SCI and their families should be counseled regarding the relatively poor prognosis associated with their injury. 

Assessment of Thoracolumbar Spine Fractures and Dislocations

Mechanisms of Injury for Thoracolumbar Spine Fractures and Dislocations

The patient’s history, physical examination, and imaging studies may all be useful for understanding the mechanism of injury underlying a thoracolumbar fracture. The spinal column may be subjected to either a single force or combination of forces including axial compression, flexion, extension, shear, and rotational moments; the injury pattern is largely determined by the overall direction and magnitude of these vectors. This information is not only important for elucidating the pathogenesis of these injuries but it may also be critical for assessing their stability and directing subsequent treatment. Unfortunately, even with a detailed history and supporting imaging studies, the mechanism of injury is often impossible to determine precisely. 
The application of an axial load to the flexed spine may generate compression fractures with disruption of the anterior vertebra with sparing of the middle and posterior portions of the body (Fig. 45-1). These end plate or wedge-shaped fractures are usually considered to be stable, but any evidence of damage to the posterior ligamentous tension band may be indicative of a more serious injury. With more significant axial forces, the fracture line may extend posteriorly through the entire vertebral body, which is characteristic of a burst injury (Fig. 45-2). Burst fractures are more unstable than compression injuries and frequently bring about compression of the neural elements secondary to the retropulsion of bony fragments into the spinal canal. Although in the past burst fractures were attributed primarily to axial loading of the spine, the authors of a recent in vitro biomechanical study reported that at least some degree of extension was also required to reproduce the interpedicular widening and canal compromise that are regularly observed in conjunction with these injuries.93 
Figure 45-1
Sagittal CT image depicting a compression fracture of the L1 vertebral body.
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Figure 45-2
 
Anteroposterior (A) and lateral (B) radiographs demonstrating a L3 burst fracture with retropulsion of bony fragments into the spinal canal noted on an axial CT image (C).
Anteroposterior (A) and lateral (B) radiographs demonstrating a L3 burst fracture with retropulsion of bony fragments into the spinal canal noted on an axial CT image (C).
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Figure 45-2
Anteroposterior (A) and lateral (B) radiographs demonstrating a L3 burst fracture with retropulsion of bony fragments into the spinal canal noted on an axial CT image (C).
Anteroposterior (A) and lateral (B) radiographs demonstrating a L3 burst fracture with retropulsion of bony fragments into the spinal canal noted on an axial CT image (C).
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A flexion moment may yield a variety of fracture patterns depending on the position of the rotational axis and the anatomic structures through which the rotational axis passes (i.e., bone or disk space) (Fig. 45-3). When the center of rotation is located within the spinal column in close proximity to the posterior longitudinal ligament, the vertebra will undergo compression as the posterior elements are distracted. However, if this point is situated more anteriorly as is the case with “seatbelt” fractures, the entire spine will fail in tension. This is often referred to as a Chance fracture after GQ Chance who described it in 1948. In contrast, a hyperextension mechanism has been implicated in the development of shear fracture–dislocations, also referred to as “lumberjack” injuries, in which the body is distracted while the posterior spine is exposed to either compressive or tensile forces46 (Fig. 45-4). 
Figure 45-3
Lateral radiograph showing a Chance fracture of L3.
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Figure 45-4
Anteroposterior (A) and lateral (B) radiographs of a L1-L2 fracture–dislocation.
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Associated Injuries with Thoracolumbar Spine Fractures and Dislocations

Given the amount of energy that is typically required to disrupt the integrity of the spinal column and the close proximity of numerous vital thoracic and abdominal viscera, it is not surprising that more than 50% of individuals with thoracolumbar fractures will be diagnosed with a nonspinal injury (involvement of one other organ system, 30%; two systems, 20%; three or more systems, 5%).134 For instance, up to 45% of patients with “seatbelt” fractures will also sustain some type of intra-abdominal injury such as a laceration of the spleen or liver.11 Moreover, the incidence of noncontiguous spinal fractures in this population has been shown to be approximately 17% to 20%.5,143 Many victims of motor vehicle accidents or falls from a significant height may also present with head injuries or fractures of the extremities. 

Signs and Symptoms: Initial Evaluation and Management of Thoracolumbar Injuries

Initial Evaluation

A thoracolumbar fracture should be suspected after polytrauma until proven otherwise, especially when the patient may be distracted by injuries to other organ systems; in one series, approximately 24% of all thoracolumbar fractures were initially missed after polytrauma.12 The emergent care of these individuals should commence immediately in the field where appropriate measures should be initiated to immobilize the entire spinal column and minimize the risk of secondary injury as patients are extricated and transported to a hospital facility. Because these fractures are routinely associated with other life-threatening injuries, the basic treatment principles set forth in the Advanced Trauma Life Support (ATLS) protocol should be meticulously followed to ensure that the airway, breathing, and circulation are adequately maintained. Resuscitation with supplemental oxygen, intravenous fluids, or cardiac pressors may be warranted in certain clinical scenarios, although it is important to differentiate patients with hypovolemia who are tachycardic and hypotensive from those with neurogenic shock where sympathetic dysfunction leads to both decreased blood pressure and a paradoxical bradycardia.154 Strict spinal precautions including logrolling techniques and the use of a backboard for all transfers must be followed until unstable spinal injuries have been ruled out by clinical examination or imaging, especially in unconscious trauma victims. 
Individuals with documented SCIs may be candidates for the administration of corticosteroid therapy. The initial mechanical contusion to the neural elements precipitates a complex biochemical cascade leading to tissue edema, microvascular changes with ischemic damage, and the production of inflammatory factors.44 The primary objective of steroids and other pharmacologic strategies is to limit the extent of any secondary neurologic insults by inhibiting the release of neurotoxic molecules, preserving membrane integrity, scavenging free radicals, and correcting electrolyte imbalances.14 According to a prospective, randomized multicenter trial known as the second National Acute Spinal Cord Injury Study (NASCIS II), a steroid regimen consisting of a 30 mg/kg bolus of methylprednisolone followed by infusion at a rate of 5.4 mg/kg/hr resulted in superior long-term neurologic outcomes.23 The ensuing NASCIS III trial demonstrated that patients who received steroids within 3 hours of their injury may need only 24 hours of therapy, whereas those whose infusions were started between 3 and 8 hours should be treated for 48 hours.24 Unfortunately, treatment with high-dose steroids has also been associated with a higher complication rate, leading many surgeons to question the appropriateness of treating trauma patients with steroids. Although these guidelines have come under criticism, they remain the “standard of care” in many centers, likely spurred in part by the litigious environment despite the lack of definitive supporting evidence.47,67,76 Other preparations that have been investigated as neuroprotective agents for patients with SCIs include lipid peroxidase inhibitors, calcium channel blockers, glycolipids, and opiate receptor antagonists.14 

History and Physical Examination

A thorough history must be obtained from the patient as well as from any other witnesses; specific details of the event may alert the treating physicians to the possibility that a thoracolumbar fracture or other spinal or appendicular injuries may be present. Relevant information includes the speed of the vehicle and the use of restraints during automobile collisions as well as the positions and point of impact of those victims involved. In addition to axial spinal pain and decreased range of motion, patients with thoracolumbar injuries may describe neurologic symptoms which provide insight into the status of the spinal cord and other neural elements. 
During the physical examination, the subject should be carefully logrolled so that the posterior spine may be visually inspected for ecchymoses, abrasions, lacerations, or swelling; it is also important to note any “seatbelt” contusions across the anterior abdomen, which are frequently observed with flexion–distraction injuries.30,57,65 Palpation of this region may elicit focal tenderness at the fracture site and reveal an obvious stepoff between the spinous processes, crepitus, soft tissue defects, or other signs of malalignment. 
A comprehensive neurologic evaluation is completed before moving the patient to establish the baseline level of function—serial assessments must be repeated over time to ensure that any further deterioration is immediately detected. The presence of neurologic injury is identified through motor, sensory, and reflex testing, although this may not be feasible in those who are unresponsive or unable to cooperate with the examination. In adults the conus medullaris usually lies behind the L1 vertebral body so individuals with fractures at the thoracolumbar junction may exhibit a variety of abnormalities based upon the anatomic structures affected. An isolated radiculopathy may manifest as a dermatomal pattern of altered sensation, myotomal weakness, or hyporeflexia, whereas injuries to the spinal cord, conus medullaris, or cauda equina may give rise to any number of deficits ranging from diffuse sensory and motor changes in the lower extremities to dense paraplegia and sphincter incontinence. A complete SCI must also be distinguished from spinal shock, which represents a transitory block of neurologic impulses that ordinarily lasts no longer than 48 hours. The bulbocavernosus reflex is elicited by stimulating the glans penis or clitoris, which should bring about an involuntary contraction of the anus; the long-term prognosis of a patient cannot be reliably ascertained until this reflex arc returns, which signifies that the episode of spinal shock has resolved. Furthermore, the sparing of sacral sensation and maintenance of rectal tone are also signs of an incomplete injury because they confirm that at least some neural pathways are still intact. SCIs may be classified using either the Frankel system or the more detailed American Spinal Injury Association (ASIA) scoring method in which muscle strength is graded from 0 to 5 and sensation to both pin prick and light touch is recorded throughout the entire body52,103 (Fig. 45-5). 
Figure 45-5
American Spinal Injury Association (ASIA) worksheet for classifying spinal cord injuries.
 
(American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury, revised 2013; Atlanta, GA. Reprinted 2013.)
(American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury, revised 2013; Atlanta, GA. Reprinted 2013.)
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Figure 45-5
American Spinal Injury Association (ASIA) worksheet for classifying spinal cord injuries.
(American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury, revised 2013; Atlanta, GA. Reprinted 2013.)
(American Spinal Injury Association: International Standards for Neurological Classification of Spinal Cord Injury, revised 2013; Atlanta, GA. Reprinted 2013.)
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Imaging and Other Diagnostic Studies for Thoracolumbar Spine Fractures and Dislocations

Plain Radiographs

Although a patient’s history or physical examination findings are generally suggestive of a spinal fracture, a complete battery of imaging studies may be required to confirm the diagnosis of a thoracolumbar injury. In most clinical centers, conventional radiography is still the most accessible and expedient method for visualizing the spinal column. In addition to displaying any irregularities in coronal alignment, anteroposterior (AP) views may reveal interpedicular widening characteristic of lateral displacement of burst fracture fragments or of increased spinous process distance suggestive of damage to the posterior ligamentous complex (PLC).55,75 A lateral radiograph may be used to quantify kyphotic deformities through measurement of the associated Cobb angle, which is an angle subtended by lines parallel to the superior and inferior endplates of the vertebrae cranial and caudal to the injury level, respectively (Fig. 45-6). The amount of vertebral collapse may be determined by calculating the height of the fractured body and expressing it as a percentage of the average height of adjacent levels. For certain fractures, the magnitude of compression may be more precisely described by measuring both the anterior and posterior margins of the body. The intersection of lines drawn parallel to the end plates and the posterior cortex of the fractured body is known as the posterior vertebral angle, which may be used to differentiate compression fractures from more unstable burst injuries.110 Although translation in the sagittal plane may normally be recognized by scrutinizing the anterior and posterior vertebral lines, the bony contours are often obscured by pre-existing spondylosis, which will decrease the utility of these anatomic markers (Fig. 45-7). 
Figure 45-6
Radiographic method for evaluating the deformity associated with a thoracolumbar fracture.
 
The kyphosis may be assessed by determining the Cobb angle, defined by the angle of intersection between the superior endplate of the vertebra cephalad to the fracture (T12, dashed line) and the inferior endplate of the caudal vertebra (L2, dashed line). Similarly, the amount of collapse may be calculated by measuring the heights of both the anterior and posterior margins (A, B) of the fractured body and expressing them as percentages of the corresponding values derived from the adjacent, uninjured segments using the formulas listed above.
The kyphosis may be assessed by determining the Cobb angle, defined by the angle of intersection between the superior endplate of the vertebra cephalad to the fracture (T12, dashed line) and the inferior endplate of the caudal vertebra (L2, dashed line). Similarly, the amount of collapse may be calculated by measuring the heights of both the anterior and posterior margins (A, B) of the fractured body and expressing them as percentages of the corresponding values derived from the adjacent, uninjured segments using the formulas listed above.
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Figure 45-6
Radiographic method for evaluating the deformity associated with a thoracolumbar fracture.
The kyphosis may be assessed by determining the Cobb angle, defined by the angle of intersection between the superior endplate of the vertebra cephalad to the fracture (T12, dashed line) and the inferior endplate of the caudal vertebra (L2, dashed line). Similarly, the amount of collapse may be calculated by measuring the heights of both the anterior and posterior margins (A, B) of the fractured body and expressing them as percentages of the corresponding values derived from the adjacent, uninjured segments using the formulas listed above.
The kyphosis may be assessed by determining the Cobb angle, defined by the angle of intersection between the superior endplate of the vertebra cephalad to the fracture (T12, dashed line) and the inferior endplate of the caudal vertebra (L2, dashed line). Similarly, the amount of collapse may be calculated by measuring the heights of both the anterior and posterior margins (A, B) of the fractured body and expressing them as percentages of the corresponding values derived from the adjacent, uninjured segments using the formulas listed above.
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Figure 45-7
Note the break in the posterior vertebral line (PVB) observed on this lateral radiograph of a fracture–dislocation.
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Figure 45-7
Any interruptions in the lines drawn along the anterior or posterior aspects of the vertebral bodies may be suggestive of a thoracolumbar injury with translation in the sagittal plane.
Note the break in the posterior vertebral line (PVB) observed on this lateral radiograph of a fracture–dislocation.
Note the break in the posterior vertebral line (PVB) observed on this lateral radiograph of a fracture–dislocation.
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Several authors have proposed that a segmental kyphosis larger than 30 degrees may reflect PLC disruption, particularly at the thoracolumbar junction.77,161 Similarly, translation greater than 2.5 mm in any plane or vertebral body height loss of 50% or greater has been reported to represent failure of the posterior ligaments.121,163 Even though these guidelines have become well accepted by many physicians, their reliability for predicting posterior instability has not been supported by Level I evidence and a recent study failed to find associations between either kyphosis or vertebral body height loss and PLC injury.125 
For stable burst fractures and other thoracolumbar injuries that can be managed nonoperatively, it is important to obtain standing radiographs in the orthosis to ensure that there is no further collapse or progressive kyphosis once the patient is mobilized. In one investigation, 28 patients with fractures located between T11 and L2 that were initially thought to be amenable to conservative treatment required surgical intervention because of previously unrecognized deformity on weight-bearing radiographs.113 

Computed Tomography

Computed tomography (CT) delivers high-resolution, multiplanar reconstructions of the spinal column that frequently provide more information about the extent of a thoracolumbar injury than radiographs alone, which may yield an incorrect diagnosis in as many as 25% of individuals with burst fractures and underestimate their amount of canal compromise by 20%.13,85 Thin-cut CT images (less than 2 mm) are able to depict comminution of the vertebral body as well as the size and location of any retropulsed fragments, all of which may influence the manner in which these injuries are addressed.105,106 (Fig. 45-8). Once again, the shape of the canal as defined by the sagittal-to-transverse diameter ratio derived from axial views of the spine has been reported to be predictive of neurologic function.152 CT is also the best modality for identifying fractures of the posterior elements that may otherwise be missed on biplanar radiographs. Because of its greater sensitivity and efficiency, a single helical CT scan has been shown to be preferable to a series of plain radiographs for screening polytrauma patients who may have spinal injuries.73,166 
Figure 45-8
 
Sagittal (A) and axial (B) computed tomography images of a burst fracture at the thoracolumbar junction with approximately 50% canal compromise secondary to the retropulsion of bony fragments posteriorly into the spinal canal.
Sagittal (A) and axial (B) computed tomography images of a burst fracture at the thoracolumbar junction with approximately 50% canal compromise secondary to the retropulsion of bony fragments posteriorly into the spinal canal.
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Figure 45-8
Sagittal (A) and axial (B) computed tomography images of a burst fracture at the thoracolumbar junction with approximately 50% canal compromise secondary to the retropulsion of bony fragments posteriorly into the spinal canal.
Sagittal (A) and axial (B) computed tomography images of a burst fracture at the thoracolumbar junction with approximately 50% canal compromise secondary to the retropulsion of bony fragments posteriorly into the spinal canal.
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Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is the “gold standard” technique for visualizing soft tissue injuries associated with thoracolumbar fractures including disk herniation, epidural hematoma, ligamentous injury, or intrasubstance injury to the spinal cord itself. Pathologic findings on MRI may play a crucial role in determining the specific treatment and the long-term prognosis of these individuals; for example, evidence of myelomalacia on MRI studies is associated with decreased motor recovery after SCI.148 Although MRI of the thoracolumbar spine is not mandatory in the absence of any neurologic deficits, these scans may be necessary for patients who demonstrate clinical signs or symptoms of neural element compression. MRI is considered to be the optimal noninvasive strategy for judging whether the PLC is intact, especially when radiographs are normal.97 On sagittal views of the spine, any edema involving the posterior supporting structures may be interpreted as a sign of a traumatic insult to the PLC, which has been incorporated by contemporary thoracolumbar injury classification algorithms.96,151,153 Whereas a strain-type injury usually gives rise to diffuse signal changes within the ligaments, the presence of a discrete stripe of fluid extending through these tissues on fat suppressed T2-weighted images is indicative of a frank disruption of the posterior tension band (Fig. 45-9). The use of MRI for gunshot wounds involving the spine is somewhat controversial; some groups have proposed that the magnetic forces may lead to further harm as the bullet moves within the tissues, while others maintain that this modality is safe for these cases.50,144 Nevertheless, it should be anticipated that the metal artifact from these fragments will adversely affect the quality of the images.15 
Figure 45-9
Sagittal T2-weighted magnetic resonance image of a L3 Chance fracture with edema evident between spinous processes of L2 and L3 suggestive of an associated ligamentous injury.
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Additional Studies

Aside from the thoracolumbar region, it is also important to image the entire spinal column to rule out any other noncontiguous fractures. Furthermore, diagnostic studies of other anatomic structures should be performed on the basis of the fracture pattern or presumed mechanism of injury. Since this patient population often experiences attendant trauma to their extremities or other organ systems, it may be prudent to request radiographs of the lower extremities for those with burst fractures and order an abdominal CT or ultrasound when seatbelt-type injuries are encountered. 

Fracture Classification of Thoracolumbar Spine Fractures and Dislocations

Although a myriad of classification systems for thoracolumbar fractures have been introduced over the past several decades, there is still no consensus among trauma experts regarding the best method for categorizing these injuries in part due to the complexity of normal spinal anatomy and biomechanics and ongoing uncertainty about how to define fracture stability.45,75,86,101,106,118 As with any heterogeneous collection of pathologic conditions, the ideal method for classifying spinal injuries should be comprehensive yet easy to apply so that it possesses sufficient reliability and reproducibility. By integrating modern imaging technology and taking advantage of an improved understanding of the natural history of thoracolumbar fractures, the goal should be to stratify injuries according to severity to direct treatment and predict patient outcomes. An effective classification algorithm also would allow effective communication about fracture morphology between different practitioners taking care of these individuals and facilitate clinical research. 
One of the earliest classification schemes was described by Denis, who attempted to elucidate the concept of spinal stability by assigning osseous and soft tissue structures into one of three columns: anterior (anterior half of vertebra/disk and anterior longitudinal ligament), middle (posterior half of vertebra/disk and posterior longitudinal ligament), and posterior (posterior elements including the pedicles, facet joints, and remaining ligaments)45 (Fig. 45-10). This system divides thoracolumbar injuries into four principal categories—compression, burst, Chance, and fracture–dislocations—with an additional 16 subgroups (Fig. 45-11). With this paradigm, the greatest emphasis is placed on the middle column such that any injury extending into this portion of the spine is generally assumed to be unstable. However, because it does not take into account the use of advanced imaging modalities or the status of the PLC, the Denis algorithm may be overly simplistic and does not adequately direct the management of these fractures.120,168 
Figure 45-10
 
Denis three-column model of spinal stability which involves anterior (anterior half of vertebra/disc and anterior longitudinal ligament), middle (posterior half of vertebra/disc and posterior longitudinal ligament), and posterior (posterior elements including the pedicles and facet joints and the remaining ligaments) columns. According to this paradigm, any injury extending into the middle column is largely considered to be unstable.
Denis three-column model of spinal stability which involves anterior (anterior half of vertebra/disc and anterior longitudinal ligament), middle (posterior half of vertebra/disc and posterior longitudinal ligament), and posterior (posterior elements including the pedicles and facet joints and the remaining ligaments) columns. According to this paradigm, any injury extending into the middle column is largely considered to be unstable.
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Figure 45-10
Denis three-column model of spinal stability which involves anterior (anterior half of vertebra/disc and anterior longitudinal ligament), middle (posterior half of vertebra/disc and posterior longitudinal ligament), and posterior (posterior elements including the pedicles and facet joints and the remaining ligaments) columns. According to this paradigm, any injury extending into the middle column is largely considered to be unstable.
Denis three-column model of spinal stability which involves anterior (anterior half of vertebra/disc and anterior longitudinal ligament), middle (posterior half of vertebra/disc and posterior longitudinal ligament), and posterior (posterior elements including the pedicles and facet joints and the remaining ligaments) columns. According to this paradigm, any injury extending into the middle column is largely considered to be unstable.
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Figure 45-11
 
Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Figure 45-11
Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Denis classification system for thoracolumbar fractures categorizes these injuries into four major categories with multiple subgroups based on the three-column theory of spinal stability: A: Compression (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, anterior body). B: Burst (type A, both endplates; type B, superior endplate; type C, inferior endplate; type D, rotational deformity; type E, lateral translation). C: Flexion–distraction (type A, bony involving one segment; type B, soft tissues of one segment; type C, bony involving two segments; type D, soft tissues of two segments). D: Fracture–dislocations (type A, bony involving one segment; type B, soft tissues of one segment; type C, two level injuries).
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Unlike the Denis scheme, the AO (Magerl) system proposes to use the primary forces that are applied to the spinal column as the main criterion for segregating thoracolumbar injuries.101 In this scheme, groups A, B, and C are composed of fractures generated by compression, distraction, and torsional/rotational loads, respectively (Fig. 45-12). The AO algorithm features multiple levels of organization, which are not only designed to specify the location, morphology, and direction of displacement for each fracture but also allow for a distinction to be made between bony and soft tissue injuries. The inter- and intraobserver reliabilities of the Denis and AO systems have been reported by a number of independent investigators. In one study, the most basic subcategory of the Magerl scheme (i.e., A, B, or C) exhibited only a fair amount of agreement (κ = 0.33) with an interobserver reliability of 67%.19 In their comparisons of these classification systems, Oner et al.120 and Wood et al.169 both concluded that the Denis scheme was more reproducible than the AO method. However, from these analyses it is clear that neither algorithm is without flaw. The AO system is more inclusive but is less practical for clinical use because of the complicated alphanumeric scoring protocol which reduces its interobserver reliability. Conversely, the more straightforward Denis paradigm is associated with improved interobserver agreement, but it may be too simplistic so that unusual fracture configurations may not be adequately described. 
Figure 45-12
 
AO/Magerl classification system for thoracolumbar injuries categorizes these injuries into three primary types according to the vector forces applied to the spine: A, compression; B, distraction; C, rotation.
AO/Magerl classification system for thoracolumbar injuries categorizes these injuries into three primary types according to the vector forces applied to the spine: A, compression; B, distraction; C, rotation.
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Figure 45-12
AO/Magerl classification system for thoracolumbar injuries categorizes these injuries into three primary types according to the vector forces applied to the spine: A, compression; B, distraction; C, rotation.
AO/Magerl classification system for thoracolumbar injuries categorizes these injuries into three primary types according to the vector forces applied to the spine: A, compression; B, distraction; C, rotation.
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Other classification systems have been developed with the goal of guiding treatment and providing prognostic information about these injuries. After reviewing the radiographs and CT scans of 100 thoracolumbar fractures, McAfee et al.105 separated these injuries into six discrete groups: wedge-compression, stable and unstable burst, Chance, flexion–distraction, and translational. With its emphasis on the mechanism by which the middle column failed, this scheme was able to determine which type of instrumentation (i.e., distraction or compression) was most suitable for each fracture. McCormack et al.106 devised the “load-sharing classification,” which uses a grading system to assess vertebral body comminution, displacement of bony fragments, and post-traumatic kyphosis as a means of establishing which injuries may be appropriately managed with immobilization alone or short-segment transpedicular constructs limited to the levels immediately above and below the fracture site (Fig. 45-13). By identifying cases that were complicated by implant breakage, the authors suggested that a point total greater than 6 required a concomitant anterior arthrodesis with a strut graft. The load sharing classification algorithm has since been validated by both in vitro biomechanical experiments and other clinical series.6,39,122,158 
Figure 45-13
 
The load sharing classification system for thoracolumbar fractures identifies injuries that may be appropriately treated with short-segment posterior instrumentation constructs by assigning points based on the extent of vertebral body comminution, apposition of the bony fragments, and the degree of focal kyphosis.
The load sharing classification system for thoracolumbar fractures identifies injuries that may be appropriately treated with short-segment posterior instrumentation constructs by assigning points based on the extent of vertebral body comminution, apposition of the bony fragments, and the degree of focal kyphosis.
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Figure 45-13
The load sharing classification system for thoracolumbar fractures identifies injuries that may be appropriately treated with short-segment posterior instrumentation constructs by assigning points based on the extent of vertebral body comminution, apposition of the bony fragments, and the degree of focal kyphosis.
The load sharing classification system for thoracolumbar fractures identifies injuries that may be appropriately treated with short-segment posterior instrumentation constructs by assigning points based on the extent of vertebral body comminution, apposition of the bony fragments, and the degree of focal kyphosis.
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In an effort to overcome inadequacies of antecedent classification systems, Vaccaro et al.153 developed the Thoracolumbar Injury Severity Score (TLISS), an innovative paradigm that focuses on three key parameters thought to reflect the global stability of the disrupted spinal column: (a) mechanism of injury as interpreted from imaging studies, (b) integrity of the PLC, and (c) neurologic status. Point values associated with each category are combined to calculate a total score that may assist in the clinical decision-making process in treating the fracture. Despite its excellent reliability as demonstrated in previous prospective investigations,71,149 the TLISS scheme was revised so that the mechanism category was replaced with fracture morphology, which was thought to be a more objective variable for surgeons to evaluate. The modified algorithm was renamed the Thoracolumbar Injury Classification and Severity Score (TLICS)151 (Table. 45-1). In a recent prospective, comparative study of these two systems, the interrater reproducibility of the TLISS scheme was found to be superior to TLICS, suggesting that a retrospective evaluation of mechanism of injury may actually be more informative than a description of its morphology.162 Regardless, since mechanism and morphology are closely related and contribute to assessment of spinal instability, either factor may be useful during the classification and subsequent treatment of thoracolumbar fractures. 
 
Table 45-1
Thoracolumbar Injury Classification and Severity Score
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Table 45-1
Thoracolumbar Injury Classification and Severity Score
Parameter Points
Morphology
  •  
    Compression
  •  
    Burst
  •  
    Translational/rotational
  •  
    Distraction
1
2
3
4
Neurologic status
  •  
    Intact
  •  
    Nerve root injury
  •  
    Spinal cord/conus medullaris injury
  •  
    Complete
  •  
    Incomplete
  •  
    Cauda equina
0
2
2
3
3
Posterior ligamentous complex
  •  
    Intact
  •  
    Indeterminate
  •  
    Disrupted
0
2
3
Treatment recommendations
Total score Treatment
≤3 Nonoperative
4 Indeterminate (nonoperative vs. operative)
≥5 Operative
 

From: Vaccaro AR, Lehman RA Jr, Hurlbert RJ, et al. A new classification of thoracolumbar injuries: The importance of injury morphology, the integrity of the posterior ligamentous complex, and neurologic status. Spine. 2005;30:2325–2333.

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Outcome Measures for Thoracolumbar Spine Fractures and Dislocations

Most commonly, outcomes after thoracolumbar fractures are described in terms of objective outcomes such as return to work and radiographic parameters such as fusion rate and sagittal alignment. As the emphasis on reporting patient-centered outcomes has developed, surgeons have begun to use these instruments in reporting outcomes for patients treated for thoracolumbar fractures and dislocations although, as with all traumatic injuries, preinjury scores are typically not available. In choosing outcomes to collect and report, surgeons must consider the difference between general health and disease-specific outcome measures. General health outcome measures such as the SF-36 and SF-12 have the advantage of being comparable to other health states and can be used to generate a utility score, a metric used in cost-effectiveness analysis. In addition, the SF-36 has been shown to have a 4-week recall meaning administration of this questionnaire could be used to determine a preinjury score. In contrast, the Oswestry Disability Index (ODI) is a disease-specific outcome measure which is intended to be used to evaluate function and disability related to the lumbar spine. In this sense, it can be expected that changes in function and disability related to the lumbar spine would be more accurately reflected by the ODI as opposed to general health measures such as the SF-12, which also reflects other changes in a patient’s health unrelated to the spine. A limitation of the ODI is that its utility in measuring disability related to thoracic injuries has not been studied. Despite the development of these validated outcomes questionnaires, it remains important to describe outcomes in terms of alignment parameters and functional parameters such as return to work. 

Surgical and Applied Anatomy and Common Surgical Approaches for Thoracolumbar Spine Fractures and Dislocations

Surgical and Applied Anatomy of the Thoracolumbar Spine

Osseous and Ligamentous Structures

The vertebral bodies in the thoracolumbar spine increase in size from rostral to caudal and are bordered by intervertebral disks both superiorly and inferiorly. Intervertebral disks are composed of an outer circumferential layer of collagen known as the annulus fibrosis that surrounds a soft, hydrophilic central core called the nucleus pulposus (Fig. 45-14). The purpose of the annulus fibrosis is to counteract torsional, tensile, and axial forces whereas the nucleus pulposus resists compressive loads. The vertebrae are also connected by the anterior and posterior longitudinal ligaments (ALL and PLL), which stabilize the spinal column during extension and flexion, respectively (Fig. 45-15). 
Figure 45-14
Schematic drawing of the intervertebral disc, which is composed of an outer circumferential layer of fibrous tissue referred to as the annulus fibrosis surrounding a gelatinous, hydrophilic core known as the nucleus pulposus.
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Figure 45-15
Sagittal cross-sectional anatomic diagram depicting the osseous and soft tissue structures of the thoracolumbar spine.
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The posterior elements that form the protective neural arch include the pedicles, laminae, transverse and spinous processes, and facet (zygoaphophyseal) joints. The pedicles are short, tubular protuberances projecting from the vertebral bodies whose dimensions have been shown to vary throughout the thoracolumbar spine.111 The pedicles between T3 and T9 typically exhibit the smallest diameters, measuring less than 5 mm at certain levels; in contrast, the average widths of the lumbar pedicles range from 9 mm at L1 to 18 mm at L5.141 The remainder of the neural arch consists of bilateral laminae, which coalesce in the midline to form the spinous process. The zygoapophyseal joints involve the superior and inferior facets, which arise from the laminae of two adjacent vertebrae. In the upper thoracic spine, these synovial articulations are aligned in the coronal plane, which restricts AP translation, whereas the sagittal orientation of those in the lower thoracic and lumbar regions minimizes medial–lateral displacement. The transverse process marks the junction between the pedicle, pars interarticularis, and superior facet. These protuberances serve as attachment sites for numerous paraspinal muscles and supporting ligaments, especially in the thoracic spine, where they also articulate with the rib head anteriorly, which confers greater stability to this portion of the spine relative to cervical and lumbar regions. 
The spaces between adjoining laminae are traversed by ligamentum flavum, a flexible connective tissue that covers the posterior aspect of the dura. Successive spinous processes are linked by inter- and supraspinous ligaments. The combination of ligamentous and capsular structures posterior to the vertebral body are collectively referred to as the Posterior Ligamentous Complex (PLC). Following a traumatic insult to the thoracolumbar spine, it is essential that the integrity of these ligaments (and capsules) be assessed because disruption of this fibrous tension band may be indicative of an unstable injury. 
In the thoracolumbar spine, the thecal sac is bounded by the vertebral body, intervertebral disk and PLL anteriorly, the pedicles and facet joints laterally, and the laminae and ligamentum flavum posteriorly. Encroachment of the spinal cord or nerve roots after thoracolumbar fracture is usually attributed to the posterior retropulsion of bony fragments from the vertebral body; however, injury to any structure may diminish the cross-sectional area of the spinal canal and bring about clinically significant compression of the neural elements. 

Spinal Cord

The central and peripheral nervous systems interface with one another at the spinal cord, which is composed of specialized arrangements of neurons and axons corresponding to its gray and white matter, respectively. For instance, motor signals from the cerebral hemisphere decussate within the brain and travel distally in the lateral corticospinal tracts. The axons to the upper extremities are located more centrally than those destined for the lower extremities so that patients with central cord injuries will often display more pronounced weakness in their arms compared to their legs. Likewise, sensory impulses ascend proximally within segregated zones of the spinal cord depending upon the type of neuron that has been activated. Pressure, vibration, and proprioception stimuli are transmitted in the ipsilateral dorsal columns before being received by the contralateral cerebral cortex, whereas information about pain and temperature contained within the spinothalamic pathways crosses over at the level of the spinal cord. Thus, individuals with a Brown-Sequard lesion, which results from a hemisection of the spinal cord, will classically demonstrate deficits in ipsilateral light touch, proprioception, and motor strength with loss of contralateral pain and temperature sensation. The spinal cord is coupled to the peripheral nerve rootlets of the cauda equina by the conus medullaris, which most commonly is found between L1 and L2. 
Although the thoracic region is protected by the stabilizing effects of the rib cage, fractures involving this portion of the spine are associated with a high risk of catastrophic neurologic injury. The ratio of dimensions of the spinal canal to the spinal cord is smallest in the thoracic spine so that there is a greater risk of compression with any degree of canal compromise. Furthermore, the thoracic spine represents a vascular watershed area whose circulation is predominantly supplied by the artery of Adamkiewicz, which perfuses the cord in a retrograde fashion after entering a single intervertebral foramen between T9 and L2, most commonly on the left side. 

Thoracolumbar Spine Fracture and Dislocation Treatment Options

Nonoperative Treatment of Thoracolumbar Spine Fractures and Dislocations

Indications/Contraindications

The optimal method for managing thoracolumbar fractures is governed by both biomechanical and clinical considerations such as the ability of the spine to withstand physiologic stresses and the presence of any neurologic deficits, associated traumatic injuries, or other relevant medical issues. The objectives of every therapeutic strategy are the same regardless of whether a fracture is addressed surgically or with nonoperative measures: maintain or restore spinal stability, correct any deformities in the sagittal or coronal planes, maximize neurologic recovery, improve pain, and allow for prompt rehabilitation. In general, many patients with thoracolumbar injuries who do not demonstrate any clinical or radiographic findings consistent with neural compression or instability may be treated nonsurgically with immobilization and early ambulation. 
Although plaster jackets were used extensively in the past to support the fractured spinal column, these techniques have largely been supplanted by a number of different external braces. A Jewett device and other hyperextension appliances are designed to resist flexion but are less apt to control rotation or lateral bending. A prefabricated or custom-fit “clamshell” thoracolumbosacral orthosis (TLSO) reduces motion in multiple planes and may be better suited for more unstable fractures.94 Miller et al.115 compared the stabilizing effects of a simple corset, a Jewett brace, and a TLSO on the mobility of the lumbar spine. Although both the Jewett orthosis and the TLSO limited motion in the lower lumbar spine, none of these braces were able to completely eliminate all movement. Moreover, the L5-S1 segment was not sufficiently stabilized by any of these appliances and some of these individuals actually exhibited hypermobility at this level while using the braces. There are some data to suggest that the supplementation of these braces with a leg cuff may impart greater stability to the spine.155 Similarly, a cervical extension may also be beneficial for inhibiting any pathologic motion that may occur with fractures of the upper thoracic spine (i.e., above T7). 
Given the overall stability of their injuries, the majority of patients with compression fractures may experience bony healing and symptomatic relief with approximately 12 weeks of immobilization.150 Nevertheless, compression injuries that demonstrate greater than 50% height loss or 25 degrees of focal kyphosis, disruption of the PLC, or any other signs of obvious instability on imaging studies should be followed closely because these injuries are predisposed to further collapse and progressive deformity despite the initiation of a suitable bracing regimen. Folman and Gepstein51 noted in their retrospective review of 85 patients with traumatic thoracolumbar wedge fractures that even though most of these injuries were adequately managed with conservative measures alone, a large proportion of these individuals continued to have chronic low back pain whose intensity correlated with the amount of segmental kyphosis. 
Burst injuries are produced when the spine is subjected to more substantial axial forces and are frequently observed with higher-energy trauma. Because they characteristically involve the middle and posterior aspects of the vertebral body, burst fractures are by definition more unstable than compression injuries and any retropulsed fragments may lead to significant canal stenosis with ensuing neurologic deficits. Burst fractures with less than 50% height loss or 25 degrees of focal kyphosis and those with less than 50% of associated canal compromise have been described as not requiring surgery;145 unfortunately, these guidelines have not been properly validated by the existing literature. A period of immobilization lasting up to 3 months may be acceptable for patients with stable burst fractures who have a normal neurologic examination and an intact PLC as well as those with unstable injuries who are not able to tolerate an operative procedure, treatment recommendations supported by a recent meta-analysis.62,74,109,128 Individuals who present with complete SCIs secondary to burst fractures may also be candidates for conservative care. Even without surgery, the displaced fragments of burst injuries have been shown to undergo spontaneous remodeling, which may increase the patency of the spinal canal and perhaps relieve impingement of the neural elements.43 Any patient with a burst fracture who is being braced should be regularly assessed by repeating standing radiographs in the orthosis to ensure that there is no further collapse of the vertebral body or increase in segmental kyphosis. 
Multiple investigators have confirmed that favorable long-term outcomes may be achieved with the closed management of thoracolumbar burst fractures in the absence of any instability or neurologic abnormalities.6,9,116,117,160 Chow et al.34 also recorded excellent results with hyperextension casting of 24 burst injuries that were categorized as being unstable according to the Denis classification system, but only 10 of these fractures actually demonstrated interspinous widening or any other radiographic findings which may be indicative of PLC disruption. 
Because of their gross instability affecting the anterior and posterior spinal elements, flexion–distraction injuries and fracture–dislocations are rarely managed without surgery with the exception of some purely bony Chance fractures.61,98 In certain circumstances, patients with a bony Chance injury who have a normal neurologic examination and less than 15 degrees of kyphosis may be braced in hyperextension as long as a satisfactory reduction is able to be maintained until the bony fragments have consolidated.10 Conversely, reliable healing of soft tissue flexion–distraction injuries and virtually all fracture–dislocations is unlikely to be attained if internal fixation is not used to reestablish the normal alignment and restore biomechanical integrity of the spine. 

Operative Treatment of Thoracolumbar Spine Fractures and Dislocations

Indications/Contraindications and Approach Selection

Even though a number of thoracolumbar fracture patterns may be treated with a rigid orthosis and prompt mobilization, a large subset of these injuries are more effectively addressed with surgery. Operative intervention is intended to convey immediate stability to the spine, allow for the correction of deformities, and optimize neurologic improvement by directly or indirectly relieving any residual impingement on the neural elements; for these reasons, surgical techniques may have the potential to enhance clinical outcomes, facilitate rehabilitation, and avoid many of the adverse consequences of nonoperative treatment.20,165. Furthermore, a systematic review by Bellabarba et al.18 demonstrated improved results with early treatment (<72 hours) of thoracic fractures in terms of days on a ventilator, days in the intensive care unit and improved respiratory health although a similar analysis of lumbar fractures only demonstrated shortened overall hospital stay. 
The operative decision-making process is dictated by several different factors such as the morphology of the fracture, the status of the PLC, the neurologic status of the patient, and any other traumatic injuries or medical comorbidities. Even though it is widely believed that individuals with unstable fractures who present with worsening kyphosis or intersegmental translation, incomplete neurologic deficits in the setting of persistent compression of the spinal cord, or radiographic evidence of significant damage to the posterior ligamentous structures will presumably benefit from surgery.109 Operative strategies may also be preferable for patients who cannot tolerate external immobilization because of their body habitus or major injuries involving the extremities or other organ systems. 
A variety of surgical procedures have been introduced to stabilize and decompress the injured thoracolumbar spine, performed either through a posterior, anterior, or circumferential approach. The ideal method for treating these fractures remains a matter of debate, and in most cases the operative plan is influenced by both clinical and radiographic concerns considering the neurologic examination, other traumatic injuries or pertinent medical conditions, the amount of sagittal plane deformity, compression and direction of compression of neural elements, and any signs of spinal instability. 

Posterior Approach

For many thoracolumbar injuries, posterior operative techniques are commonly used to reduce fractures, restore alignment, relieve compression of neural structures, and generate a solid arthrodesis of the vertebral column. One of the principal advantages of this approach is that it avoids the morbidity associated with anterior thoracolumbar exposures, potentially decreasing blood loss and operative time. Although a combination of hooks or sublaminar wires may be used in the thoracolumbar spine, these constructs have been largely replaced by transpedicular fixation systems. Since pedicle screws are inserted through the posterior elements into the vertebral body, this instrumentation confers greater stiffness to the fused segment so that larger axial and rotational forces can be applied to the spine. The increased pull-out strength of these implants allows use of short-segment constructs in certain situations, which incorporate only those segments contiguous to the injury. Such techniques must be used judiciously, however, as several reports have documented higher rates of hardware failure with resultant kyphosis when improperly used92,112,136,158 (Fig. 45-16). Adjunctive strategies to further increase strength of fixation include additional supra or infralaminar hook supplementation4,88,99 and cement augmentation of the fractured vertebra1,2,33,89,90,102,156 which may be used to reinforce limited fusions. Short-segment fixation may be inadequate in patients with osteoporotic injuries located at the thoracolumbar junction or highly comminuted fractures7; in these situations, it is prudent to utilize traditional guidelines and extend the arthrodesis two levels above and below the injury to decrease the rates of pseudarthrosis and postsurgical deformity (Fig. 45-17). 
Figure 45-16
 
Lateral radiograph demonstrating failure of a short-segment posterior instrumentation construct used to stabilize a burst fracture which continued to develop progressive collapse and kyphosis despite operative stabilization.
Lateral radiograph demonstrating failure of a short-segment posterior instrumentation construct used to stabilize a burst fracture which continued to develop progressive collapse and kyphosis despite operative stabilization.
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Figure 45-16
Lateral radiograph demonstrating failure of a short-segment posterior instrumentation construct used to stabilize a burst fracture which continued to develop progressive collapse and kyphosis despite operative stabilization.
Lateral radiograph demonstrating failure of a short-segment posterior instrumentation construct used to stabilize a burst fracture which continued to develop progressive collapse and kyphosis despite operative stabilization.
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Figure 45-17
 
Anteroposterior (A) and lateral (B) radiographs of a L3 burst injury obtained 6 months after treatment with a posterior instrumented arthrodesis extending two levels above and below the fractured vertebra. On the anteroposterior view, exuberant bone formation is evident posterolaterally, indicative of a solid fusion.
Anteroposterior (A) and lateral (B) radiographs of a L3 burst injury obtained 6 months after treatment with a posterior instrumented arthrodesis extending two levels above and below the fractured vertebra. On the anteroposterior view, exuberant bone formation is evident posterolaterally, indicative of a solid fusion.
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Figure 45-17
Anteroposterior (A) and lateral (B) radiographs of a L3 burst injury obtained 6 months after treatment with a posterior instrumented arthrodesis extending two levels above and below the fractured vertebra. On the anteroposterior view, exuberant bone formation is evident posterolaterally, indicative of a solid fusion.
Anteroposterior (A) and lateral (B) radiographs of a L3 burst injury obtained 6 months after treatment with a posterior instrumented arthrodesis extending two levels above and below the fractured vertebra. On the anteroposterior view, exuberant bone formation is evident posterolaterally, indicative of a solid fusion.
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Patients with thoracolumbar fractures who experience symptomatic neural impingement can be managed with an anterior corpectomy, but use of a posterior-based decompression is also an option.8 Through a simple laminectomy, it is possible to remove symptomatic epidural hematomas, repair traumatic dural tears, and extricate nerve roots that may have become trapped within a vertically oriented lamina fracture28 (Fig. 45-18). Alternatively, other posterolateral techniques have been described including the transpedicular, costotransversectomy, lateral extracavitary, and lateral parascapular extrapleural exposures, any of which may be used to gain access to the spinal canal and relieve encroachment of the neural elements.3,49,54,63,69,84 Because they may further destabilize an already injured spine, these posterior decompressive procedures are normally performed in conjunction with an instrumented arthrodesis to prevent the development of any iatrogenic deformities or deterioration in neurologic function. 
Figure 45-18
 
Axial computed tomography image demonstrating a lumbar burst injury resulting in symptomatic compression of the neural elements that was treated with a posterior laminectomy at the level of the fracture.
Axial computed tomography image demonstrating a lumbar burst injury resulting in symptomatic compression of the neural elements that was treated with a posterior laminectomy at the level of the fracture.
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Figure 45-18
Axial computed tomography image demonstrating a lumbar burst injury resulting in symptomatic compression of the neural elements that was treated with a posterior laminectomy at the level of the fracture.
Axial computed tomography image demonstrating a lumbar burst injury resulting in symptomatic compression of the neural elements that was treated with a posterior laminectomy at the level of the fracture.
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Aside from stabilizing the spinal column for the purpose of promoting a successful fusion, posterior instrumentation may also be used to distract across the injury site to indirectly decompress the neural elements through ligamentotaxis. While the spinal canal may be expanded by up to 50% with this maneuver, in most instances the amount of compression will only improve by less than 20%.38,70,83,139,168 This method of reduction is only feasible if the retropulsed bone remains attached to the posterior annulus via Sharpey’s fibers. Gertzbein et al.58 suggested that distraction and ligamentotaxis may be less useful for individuals with canal compromise greater than 67% because retropulsed bony fragments are rarely in continuity with the soft tissues. Furthermore, this process must be completed in a timely fashion since the efficacy of this intervention has been shown to diminish as early as 3 days after the traumatic injury as in situ healing begins.38,164,171 
Posterior surgical procedures, alone or in combination with an anterior operation, are usually selected for most unstable burst, flexion–distraction (bony and soft tissue), and fracture–dislocation injuries when there is disruption of the PLC. This approach allows for the reduction and secure fixation of the spine, thereby reconstituting the incompetent posterior tension band. A posterior arthrodesis is generally sufficient for patients with burst fractures who are neurologically intact and do not require a formal decompression; an instrumented fusion may also be appropriate for acute burst injuries associated with a moderate degree of canal compromise in the setting of a neurologic deficit when distraction and ligamentotaxis can adequately indirectly reduce any retropulsed fragments. However, as described above, certain methods for posterior stabilization such as short-segment fixation may lead to delayed hardware failure, especially in the setting of significant vertebral comminution; anterior column support is often required to restore normal sagittal plane alignment in these situations. 
An individual with a catastrophic SCI who has a poor prognosis for any meaningful neurologic recovery may benefit from a posterior arthrodesis to minimize the risk of subsequent deformity and to facilitate rehabilitation. For posterior element fractures producing a neurologic deficit, a posterior operation may be necessary to address symptomatic durotomies or free nerve roots entangled in a vertical laminar fracture. A laminectomy may also be indicated for certain injuries involving the proximal thoracic spine (e.g., T2 burst fracture) that are not amenable to exposure via thoracotomy. Finally, consideration of the substantial morbidity of an anterior approach, relevant medical comorbidities including pulmonary disorders and morbid obesity, as well as other serious injuries to the thoracic or abdominal viscera, may ultimately dictate that a thoracolumbar fracture be treated via a posterior approach. 
The success of posterior-only procedures for the surgical management of a wide range of thoracolumbar injuries has been well documented in the literature. In a consecutive series of 32 patients with unstable thoracic fractures, transpedicular screw fixation was found to be an expedient method for fusing the spine.173 Multiple studies have reported excellent clinical and radiographic outcomes following the use of posterior operative techniques for burst fractures.16,41,48,167 Several authors have also recorded significant reductions in back pain and kyphosis with open reduction and short-segment instrumented posterior arthrodesis for flexion–distraction injuries.100,147 These more limited constructs may not be rigid enough for fracture–dislocations so many practitioners have advocated longer fusions for these grossly unstable injuries in an effort to decrease the incidence of implant failure.46,126,172 

Anterior Approach

For most patients with thoracolumbar fractures resulting in neurologic abnormalities, the majority of compression may be attributed to encroachment of the canal from retropulsed fragments arising from the posterior aspect of the damaged vertebral body. An anterior exposure affords unparalleled visualization of the dura and allows for a more meticulous decompression of the neural elements48; for these reasons, anterior procedures may be more desirable than posterior-based strategies for individuals with incomplete SCIs whose imaging studies depict severe stenosis in the axial plane. Anterior column support with a strut graft or other interbody device may also be advisable for a thoracolumbar injury with considerable comminution, as noted above, which predisposes this segment to additional collapse and deformity. These load-sharing constructs are routinely augmented with instrumentation consisting of any combination of screws, staples, plates, or rods, which may enhance their biomechanical properties8 (Fig. 45-19). 
Figure 45-19
 
Postoperative anteroposterior (A) and lateral (B) radiographs of a fracture located at the thoracolumbar junction that was addressed anteriorly with a L1 corpectomy, introduction of a titanium expandable cage filled with local autograft, and placement of instrumentation.
Postoperative anteroposterior (A) and lateral (B) radiographs of a fracture located at the thoracolumbar junction that was addressed anteriorly with a L1 corpectomy, introduction of a titanium expandable cage filled with local autograft, and placement of instrumentation.
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Figure 45-19
Postoperative anteroposterior (A) and lateral (B) radiographs of a fracture located at the thoracolumbar junction that was addressed anteriorly with a L1 corpectomy, introduction of a titanium expandable cage filled with local autograft, and placement of instrumentation.
Postoperative anteroposterior (A) and lateral (B) radiographs of a fracture located at the thoracolumbar junction that was addressed anteriorly with a L1 corpectomy, introduction of a titanium expandable cage filled with local autograft, and placement of instrumentation.
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Anterior operations are typically reserved for fractures with canal compromise greater than 67% or focal kyphosis measuring at least 30 degrees.107,135 Moreover, anterior interventions are often obligatory for subacute injuries occurring more than 5 days in the past, which may no longer be able to be indirectly reduced with posterior distraction and ligamentotaxis. It may also be more practical to extirpate any symptomatic intervertebral disk herniations through an anterior approach. Posterior element fractures and other anatomic constraints (e.g., pedicles that are too small to safely accommodate screws) that preclude the placement of posterior implants may also justify the use of anterior techniques. 
The safety and efficacy of anterior procedures for specific types of thoracolumbar injuries have been established by the findings of numerous investigations. According to various retrospective reviews, patients with burst fractures who were managed with anterior decompression, strut grafting, and instrumented arthrodesis exhibited high rates of fusion with relatively few complications and nearly all of those with incomplete neurologic injuries demonstrated at least partial resolution of their deficits.41,59,66,80,81,91,104,108 In a large series of 150 consecutive burst injuries with concomitant neurologic involvement that were addressed in this fashion, solid fusions were observed in 93% of cases with a mean percentage of canal clearance of 98%; postoperatively, 95% of these individuals improved by a minimum of one neurologic category on the Frankel scale, and 96% eventually returned to work.81 Sasso et al.131 also achieved similar success when using this surgical approach for more unstable thoracolumbar fractures that included both the anterior and posterior spinal elements. At the time of final follow-up, 95% of these subjects displayed radiographic evidence of fusion and 91% had regained one or more Frankel grade. 

Circumferential (Anterior/Posterior) Approach

Even though the results of surgical interventions performed through a single approach have been favorable, a combination of anterior and posterior techniques may be indicated for certain thoracolumbar injuries. Fractures with extensive vertebral body comminution that are treated solely with posterior instrumentation may be susceptible to implant failure and sagittal plane deformity if the spinal column is not stabilized anteriorly as well132,140 (Fig. 45-20). Stand-alone anterior constructs may also be at greater risk for nonunion if the PLC is ruptured so that it is no longer able to serve as a posterior tension band to counteract any distractive forces.59 Isolated anterior reduction and fixation is also not a viable option for fracture–dislocations or other translational or rotational deformities, which ordinarily necessitate an initial reduction and arthrodesis through a posterior exposure of the spine. Because of their poor bone quality, patients with osteoporosis are susceptible to graft subsidence, segmental collapse, and pseudarthrosis with an anterior-only strategy, making them ideal candidates for a circumferential procedure. 
Figure 45-20
 
Axial (A) magnetic resonance image demonstrating a T12 burst injury with evidence of retropulsion of fracture fragments into the spinal canal. Postoperative anteroposterior radiograph (B) obtained following a procedure consisting of a T12 corpectomy with reconstruction using an expandable cage and anterior instrumentation.
Axial (A) magnetic resonance image demonstrating a T12 burst injury with evidence of retropulsion of fracture fragments into the spinal canal. Postoperative anteroposterior radiograph (B) obtained following a procedure consisting of a T12 corpectomy with reconstruction using an expandable cage and anterior instrumentation.
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Figure 45-20
Axial (A) magnetic resonance image demonstrating a T12 burst injury with evidence of retropulsion of fracture fragments into the spinal canal. Postoperative anteroposterior radiograph (B) obtained following a procedure consisting of a T12 corpectomy with reconstruction using an expandable cage and anterior instrumentation.
Axial (A) magnetic resonance image demonstrating a T12 burst injury with evidence of retropulsion of fracture fragments into the spinal canal. Postoperative anteroposterior radiograph (B) obtained following a procedure consisting of a T12 corpectomy with reconstruction using an expandable cage and anterior instrumentation.
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Given the increased morbidity of a 360-degree approach, it may be prudent to stage these interventions until it is confirmed that a second operation is warranted. To this end, interval imaging studies may be obtained after the first surgery to assist in this decision-making process. For example, a CT scan may reveal the amount of residual encroachment of the neural structures that remains following an indirect reduction of the canal using posterior distraction and ligamentotaxis, which is useful for determining whether a subsequent anterior decompression should be completed. In fact, anterior techniques may be implemented in a delayed fashion such that individuals with ongoing occlusion of neural tissues have been found to experience superior pain relief and at least partial return of their neurologic function up to several years after an initial posterior procedure.21,146 Likewise, any structural grafts or interbody devices that demonstrate any evidence of delayed or nonunion on plain radiographs may merit supplementation with transpedicular screws, which are known to be a reliable method for managing anterior constructs that do not heal.81 

Thoracolumbar Spine Fractures and Dislocations Posterior Approach

Preoperative Planning

A complete battery of diagnostic studies consisting of plain radiography, CT, or MRI should be considered before surgery because a number of radiographic findings have been shown play a critical role in determining which operative approach should be used (e.g., sagittal alignment, amount of canal compromise, and integrity of the posterior ligaments). If the arthrodesis is to be augmented with instrumentation, the dimensions of the bony pedicles should be assessed prior to surgery on sagittal and axial CT views of the spine to ascertain whether they are large enough to safely accommodate screws. Fluoroscopy or plain radiography should be readily available during these cases to identify the fractured segment and guide the placement of any implants. With the exception of individuals with complete SCIs, we typically use intraoperative neuromonitoring strategies that entail the recording of somatosensory and transcranial electric motor-evoked potentials (SSEPs and MEPs, respectively) as well as spontaneous and triggered electromyographic data, because any acute changes in this real-time electrophysiologic feedback may alert the practitioner to the possibility of impending neurologic deterioration. Even in the setting of a complete neurologic deficit, electrophysiologic monitoring is still an effective method for ensuring that the brachial plexus is not subjected to any excessive stretching during the case. 
Establishing the number of levels to incorporate in the arthrodesis remains a controversial issue. Extending the fusion so that it comprises at least the two vertebrae above and below the injury may increase the stability of the spinal column, which is essential for the treatment of fractures in which there is great deal of comminution or kyphosis. Although short-segment constructs may be appropriate for circumferential procedures or injuries involving the lower lumbar spine, this technique is not always recommended for patients with osteoporosis or those with fractures of the thoracolumbar junction who generally require more rigid fixation. 

Patient Positioning

Once the airway has been secured and an adequate level of anesthesia has been attained, the patient is positioned prone on a radiolucent operating room table such as a Jackson frame, taking care to adhere to strict spinal precautions at all times during the transfer (Fig. 45-21). In addition to making certain that all bony prominences are cushioned so that they are not subject to any undue pressure, the shoulders and other upper extremity joints should be maintained at angles less than 90 degrees to avoid a brachial plexopathy or any other neuropraxias; similarly, the hips are extended and the knees are slightly flexed to minimize the risk of sustaining a traction injury to the sciatic nerves. It is also important to ensure that the abdomen is free of any restrictive pads because any compression of visceral or vascular structures may lead to elevated intraspinal pressures and increase the amount of epidural blood loss. These maneuvers may be performed in a patient who is awake but sedated to minimize the risk of injury during positioning; alternatively, this somewhat onerous process may be avoided altogether if electrophysiologic monitoring is available to acquire potentials both at baseline and after the individual has been transferred. 
Figure 45-21
Schematic drawing of a patient who has been placed in the prone position on a Jackson spinal table.
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Approach

The skin overlying the posterior aspect of the thoracolumbar spine is sterilely prepped and draped. The iliac crests should also be included within the surgical field if autogenous bone is to be procured as graft material for an arthrodesis. The posterior thoracolumbar spine is approached through a midline skin incision based over the fracture site (Table 45-2). The subcutaneous tissues and deep fascial layer are split so that the paravertebral muscles may be elevated off the posterior elements. The subperiosteal exposure proceeds laterally until the facet joints and the transverse processes of the segments of interest are fully exposed in preparation for an instrumented spinal arthrodesis. 
 
Table 45-2
Surgical Steps for Posterior Surgical Approach
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Table 45-2
Surgical Steps for Posterior Surgical Approach
  •  
    Identification of approximate level using fluoroscopy, evaluation of postural deformity correction
  •  
    Standard midline approach to the spine using subperioseal technique, exposure to transverse processes
  •  
    Cannulation of pedicles
    •  
      Thoracic—lateral to facet midpoint along superior third of transverse process
    •  
      Lumbar—lateral aspect of facet joint, midpoint of transverse process
  •  
    Selection of pedicle screw size based on preoperative templating, direct measurement
  •  
    Reduction of facets (if necessary)
  •  
    Rods bent to desired sagittal alignment
  •  
    Attach screws at one end of rod. This allows reduction of residual deformity via cantilever method (if necessary)
  •  
    Tighten end-caps on one side of fracture to allow distraction for correction of vertebral collapse, reduction of canal compromise due to bone fragments via ligamentotaxis
  •  
    Tighten remainder of end-caps
  •  
    Visualize reduction/alignment using imaging
  •  
    Decorticate and place bone graft
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Technique

Thoracolumbar pedicles may be cannulated using the facet joint, pars interarticularis, and transverse process as anatomic landmarks (Fig. 45-22). The entry site for thoracic pedicle screws is generally located immediately lateral to the midpoint of the facet joint just lateral to the junction of the pars and superior articular process and the superior third of the transverse process. In the lumbar spine, this point is demarcated by the intersection of a vertical line that passes along the lateral aspect of the facet joint and a horizontal line that bisects the transverse process. After a cortical window has been created with a Midas Rex drill or other high-speed burr, an awl or curette is advanced through the pedicle into the vertebral body. A lateral plain x-ray can confirm the appropriate sagittal alignment of a placed pedicle marker (drill bit) or one can use the assistance of fluoroscopic visualization in multiple planes. The integrity of the channel is verified by examining the walls of the pedicle with a probe to confirm that there is a firm end point with no bony perforations. The proper length of each implant is estimated with a depth gauge and the correct diameter may be derived from preoperative CT or MR axial images, ranging from 4 mm in the upper thoracic region to as large as 7 mm in the lower lumbar spine and sacrum. The track may be tapped if needed and the screw is inserted into the spine. 
Figure 45-22
Schematic drawings identifying the anatomic landmarks commonly used for the placement of thoracic (A) and lumbar (B) pedicle screws.
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In many instances, some degree of postural reduction may be observed as the patient is positioned prone on the operating room table. For flexion–distraction injuries or fracture–dislocations, manipulation of perched facets and correction of any sagittal or coronal plane deformities are best accomplished through a posterior approach in conjunction with towel clamps, lamina spreaders, or Cobb elevators. Alternatively, many thoracolumbar injuries may be successfully reduced by taking advantage of segmental instrumentation. Following the introduction of transpedicular fixation, connecting rods of the appropriate size are cut and fashioned such that they are not only straight in the coronal plane but replicate the physiologic sagittal curvature of the spine as well. The rods are first linked to the proximal implants before being delivered to the distal anchors to restore normal alignment (Fig. 45-23). Locking the rods within the heads of the screws at only one end allows distractive forces to be applied across a burst injury with moderate canal compromise to increase the height of the collapsed vertebra and tension the ligamentous attachments to any retropulsed fragments in an attempt to bring about an indirect reduction of the fracture through ligamentotaxis (Fig. 45-24). 
Figure 45-23
Schematic drawings showing the steps involved in achieving an open reduction of a thoracolumbar fracture with correction of any resultant kyphosis.
 
After transpedicular fixation is inserted above and below the level of the injury (A), a precontoured rod is secured within the upper screws and is delivered to the lower instrumentation as part of the reduction maneuver (B).
After transpedicular fixation is inserted above and below the level of the injury (A), a precontoured rod is secured within the upper screws and is delivered to the lower instrumentation as part of the reduction maneuver (B).
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Figure 45-23
Schematic drawings showing the steps involved in achieving an open reduction of a thoracolumbar fracture with correction of any resultant kyphosis.
After transpedicular fixation is inserted above and below the level of the injury (A), a precontoured rod is secured within the upper screws and is delivered to the lower instrumentation as part of the reduction maneuver (B).
After transpedicular fixation is inserted above and below the level of the injury (A), a precontoured rod is secured within the upper screws and is delivered to the lower instrumentation as part of the reduction maneuver (B).
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Figure 45-24
Schematic drawings depicting the indirect reduction of a thoracolumbar fracture.
 
Once transpedicular fixation has been placed in the vertebrae adjacent to the level of the fracture (A), a reduction may be indirectly achieved by applying distraction across the injured segment (B) and taking advantage of ligamentotaxis to decrease the amount of canal compromise as seen in these cross-sectional images (C).
Once transpedicular fixation has been placed in the vertebrae adjacent to the level of the fracture (A), a reduction may be indirectly achieved by applying distraction across the injured segment (B) and taking advantage of ligamentotaxis to decrease the amount of canal compromise as seen in these cross-sectional images (C).
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Figure 45-24
Schematic drawings depicting the indirect reduction of a thoracolumbar fracture.
Once transpedicular fixation has been placed in the vertebrae adjacent to the level of the fracture (A), a reduction may be indirectly achieved by applying distraction across the injured segment (B) and taking advantage of ligamentotaxis to decrease the amount of canal compromise as seen in these cross-sectional images (C).
Once transpedicular fixation has been placed in the vertebrae adjacent to the level of the fracture (A), a reduction may be indirectly achieved by applying distraction across the injured segment (B) and taking advantage of ligamentotaxis to decrease the amount of canal compromise as seen in these cross-sectional images (C).
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As soon as these maneuvers have been completed, the rest of the caps are tightened to maintain the reduction that has been achieved. Final AP and lateral C-arm images or intraoperative plain radiographs are acquired to visualize the implants and evaluate the overall alignment of the spinal column. The construct may also be supplemented with transverse cross connectors to further enhance its rigidity. The facet joint capsules and any other residual soft tissues are eradicated so that the posterior elements may be adequately decorticated with gouges or a power-driven burr. The wound is copiously irrigated with antibiotic-containing solution and any active bleeding is addressed with electrocautery or thrombogenic agents. As a final step, autogenous cancellous bone is placed over the bleeding surfaces of the laminae and in the lateral gutters to promote the formation of a solid arthrodesis. A drain may be left above or below the fascia and the various layers of the incision are approximated. The preoperative and postoperative imaging studies of a patient with an unstable thoracolumbar flexion–distraction injury that was treated with a posterior reduction and instrumented arthrodesis are included in Figure 45-25
Figure 45-25
Imaging studies of a 67-year-old man who presented with a complete spinal cord injury following a motor vehicle collision.
 
A sagittal computed tomography (A) image reveals a flexion–distraction injury at T12-L1. Postoperative anteroposterior (B) and lateral (C) radiographs obtained following an open reduction and posterior instrumented fusion extending from T10 to L2.
A sagittal computed tomography (A) image reveals a flexion–distraction injury at T12-L1. Postoperative anteroposterior (B) and lateral (C) radiographs obtained following an open reduction and posterior instrumented fusion extending from T10 to L2.
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Figure 45-25
Imaging studies of a 67-year-old man who presented with a complete spinal cord injury following a motor vehicle collision.
A sagittal computed tomography (A) image reveals a flexion–distraction injury at T12-L1. Postoperative anteroposterior (B) and lateral (C) radiographs obtained following an open reduction and posterior instrumented fusion extending from T10 to L2.
A sagittal computed tomography (A) image reveals a flexion–distraction injury at T12-L1. Postoperative anteroposterior (B) and lateral (C) radiographs obtained following an open reduction and posterior instrumented fusion extending from T10 to L2.
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Postoperative Care

There is currently little evidence to suggest that postoperative bracing regimens give rise to superior fusion rates or improved outcomes, especially if the fracture has been stabilized with internal fixation. Nevertheless, we regularly immobilize these patients with a corset or TLSO for up to 3 months depending upon the nature of the injury and healing response of the patient. Patients are encouraged to ambulate as soon as possible to reduce the risk of complications that commonly occur with prolonged recumbency. Standing radiographs should also be reviewed at regular intervals to evaluate for any radiographic signs indicative of pseudarthrosis such as worsening kyphosis or collapse of the fractured vertebra. 

Potential Pitfalls and Preventative Measures

Other salient surgical pitfalls and preventative measures related to these posterior techniques are listed in Tables 45-3 and 45-4
Table 45-3
Pitfalls and Preventions for Posterior Surgical Techniques—Fracture Reduction
Pitfalls Preventions
Iatrogenic neurologic insult during reduction Use of fluoroscopic guidance
Use of spinal cord monitoring
Maintain mean arterial pressure (MAP) >85 mm Hg
Difficulty reducing sagittal plane deformities Perform surgical reduction within 3–5 days of injury before healing starts
Apply manual pressure to the apex of the kyphosis
Inadvertent disruption of the facet joints, ligaments, or other structures of segments not included in fusion may lead to adjacent segment degeneration Localization of the operative levels using fluoroscopy to target exposure
Meticulous exposure, careful landmark identification to avoid iatrogenic injury of stabilizing structures
Posterior distraction may worsen any pre-existing kyphosis, predispose to nonunion Careful restoration of sagittal alignment after reduction accomplished
Bend rod to desired sagittal contour and reduce spine to rod
Consider anterior column support
Intraoperative radiographs after instrumentation shows alignment before leaving operating room
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Table 45-4
Pitfalls and Preventions for Posterior Surgical Techniques—Instrumentation
Pitfalls Preventions
Difficulty cannulating pedicle Laminoforaminotomy may be performed along the inferomedial aspect of the superior facet allowing direct palpation of the medial pedicle
When using fluoroscopic guidance, the instrument should not appear medial to the pedicle on an anteroposterior view until it has passed into the vertebral body at depth of ∼20 mm
Fracture of pedicle when inserting pedicle screws Pedicles with dimensions that preclude safe insertion of screws may be instrumented using a lateral extrapedicular approach
Tap each screw hole by 1 mm under intended screw diameter
Skip levels with traumatic pedicle fractures to avoid pushing bone fragments into canal
Postoperative sagittal plane deformity Rods must be precisely contoured to re-establish physiologic sagittal balance
Although polyaxial screws heads may facilitate rod placement, monoaxial implants allow delivery of greater forces to the spine during deformity correction
Patients with fracture comminution, osteoporosis, or thoracolumbar junction injuries should not undergo short-segment fixation
Anterior vertebral body perforation may lead to life-threatening injuries to major blood vessels or other organs When cannulating pedicles, one hand should be braced against the patient’s body to prevent plunging
Calibrated pedicle probes and preoperative measurement of pedicle dimensions gives the surgeon insight into the appropriate depth needed to place screws
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Thoracolumbar Spine Fractures and Dislocations Anterior Approach

Preoperative Planning

As with posterior surgical techniques, a methodical review of the preoperative images is equally as important for thoracolumbar injuries that are to be managed through an anterior approach. Besides depicting the amount of canal occlusion and the degree of fracture comminution, CT scans are also indispensable for quantifying the dimensions of the adjacent vertebral bodies, which will determine the size of the strut graft and the length of the implants that may be safely placed to reconstitute the anterior spinal column. MRI studies may display a variety of pathologic conditions affecting the soft tissues such as epidural hematomas, cerebrospinal fluid leaks, traumatic disk herniations, and any intrinsic damage to the spinal cord. In particular, MRI is the most sensitive modality for detecting any disruption of the posterior ligaments, which may be a contraindication for a stand-alone anterior operation. Once again, we strongly advocate the use of electrophysiologic monitoring during anterior interventions as reliable methods for decreasing the incidence of intraoperative injuries to the neural elements. 

Patient Positioning

For any individual with an unstable thoracolumbar fracture, strict compliance with spinal precautions is absolutely mandatory to prevent any iatrogenic neurologic insults. General endotracheal intubation is performed with the patient lying supine; if a thoracotomy is required, a double-lumen tube may be used to deflate the ipsilateral lung so that the injured segment is more accessible. The patient is transferred to the lateral decubitus position and is buttressed with a bean bag or other bolsters (Fig. 45-26). It may be advantageous to shift the patient so that the fracture is situated over the break in the operating room table because any increase in flexion would be expected to expand the intercostal space to improve visualization of the spinal column and expedite placement of a strut graft. The upper arm is maintained on a Mayo stand and an axillary roll is inserted underneath the trunk to support the shoulder girdle. Both hip joints are flexed so that the iliopsoas muscles are less prominent within the surgical field. The extremities are also padded with foam or gel material to protect the skin and peripheral nerves during the case. 
Figure 45-26
Schematic drawing of a patient who has been placed in the lateral decubitus position in preparation for a thoracotomy.
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Approach

The anterolateral aspect of the patient’s flank is prepped and draped in a sterile manner from the midline of the chest wall and abdomen to the spinous processes, making sure to incorporate the iliac crest if a structural autograft is to be harvested. Fractures proximal to T11 may be addressed from either the right or the left sides, but injuries at the thoracolumbar junction or in the lumbar spine are best treated with left-sided thoracoabdominal and retroperitoneal exposures, respectively, because these approaches avoid the liver and do not require as much manipulation of the more delicate vena cava. 
In many institutions, anterior thoracic and lumbar approaches are performed by an approach surgeon. An oblique skin incision is centered over the rib one or two levels cephalad to the fracture, extending from the umbilicus to the lateral paraspinal musculature. A subperiosteal dissection is performed to detach the intercostal muscles from the rib without disturbing the neurovascular bundle along its inferior aspect. At this point, the intercostal space may be opened with or without removing the rib; if the surgeon elects to proceed with rib excision, an osteotome is used to cut the rib anteriorly at the costochondral junction and posteriorly where it articulates with the transverse process. The ribs are spread with a self-retaining thoracotomy retractor and the lung is selectively deflated by the anesthesia team. For fractures of the thoracolumbar junction or other injuries for which the diaphragm must be released, it is recommended that a cuff of tissue measuring at least 1 cm should be left in continuity with the chest wall and marked with sutures to permit an anatomic repair at the conclusion of the surgery. An incision is made through the parietal pleura of the thoracic cavity so that it may be dissected off the spinal column above and below the injury. When exposing the T9-T12 levels, it may be useful to temporarily clamp the segmental arteries and verify that there are no subsequent changes in neuromonitoring potentials before sacrificing them in an effort to decrease the risk of injury to the artery of Adamkiewicz and possibly avoid precipitating an ischemic insult to the spinal cord. 
For fractures of the lumbar spine, the skin incision may be extended distally along the anterolateral portion of the flank toward the abdomen and the lateral border of the rectus abdominis muscle; the subcutaneous tissues and the musculature of the abdominal wall (i.e., external and internal obliques, transverses abdominis) are divided in line with this incision. With blunt dissection, the peritoneal contents are mobilized and retracted medially along with the great vessels to gain access to the retroperitoneal space and the spinal column. 
Once the approach to the anterior spine has been completed, the “hills” of the convex discs and the “valleys” corresponding to the concave vertebrae should be apparent. Care must be taken to carefully ligate the segmental vessels overlying the vertebral bodies to minimize any bleeding during the remainder of the procedure. A fracture routinely creates an obvious deformity of the spine, but it is always recommended that a needle be placed in one of the discs adjacent to the vertebral body presumed to be injured so that an intraoperative radiograph may be obtained to visualize the segment of interest. Once the level of the fracture has been identified, the iliopsoas muscle is cleared off the vertebra and retracted away from the bony fragments. 

Technique

Once the level has been identified definitively on imaging, the decompression surgery (Table 45-5) can begin. For thoracic injuries, any remaining portions of the rib head where it articulates with the transverse process are detached to reveal the posterior elements (i.e., the pedicle) corresponding to the level of the fracture (Fig. 45-27). A Penfield dissector is introduced into the neuroforamen, where it may not only be used as both a retractor but also as a tool for palpating the bony margins of the pedicle, which is subsequently skeletonized with a burr so that it may be easily extracted with a Kerrison rongeur. The excision of this structure proceeds ventrally to the point where it joins the posterior vertebral body until the anterior and lateral portions of the thecal sac are clearly visible. The intervertebral disks adjacent to the fracture are sharply divided with a scalpel and the nucleus pulposus tissue is extracted with a pituitary rongeur or curettes. 
Figure 45-27
Schematic drawings illustrating the steps involved in performing a corpectomy for the purpose of decompressing the neural elements.
See text for operative technique.
See text for operative technique.
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Table 45-5
Surgical Steps for Anterior Surgical Approach
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Table 45-5
Surgical Steps for Anterior Surgical Approach
  •  
    Anterior approach performed by approach surgeon
  •  
    Removal of rib head for thoracic levels
  •  
    Pedicle removed to provide access to posterior vertebral body
  •  
    Discectomy above and below affected vertebra
  •  
    Bone removed first from anterior and middle of vertebra
  •  
    Posterior cortex and bone in canal delivered into cavity within vertebra using curette
  •  
    Work across vertebra until contralateral pedicle reached
  •  
    Remove cartilage from endplates
  •  
    Reduce kyphosis associated with injury
  •  
    Structural bone graft or cage placed into corpectomy defect
  •  
    If used, anterior instrumentation placed in posterolateral aspect of body
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During the initial stages of the vertebrectomy, the larger fracture fragments are removed with osteotomes, rongeurs, or a burr and saved as bone graft material. An angled curette may then be used to deliver any smaller pieces of bone out of the canal and into the cavity that has been formed anteriorly. If possible, the anterior longitudinal ligament with its bony attachments should be preserved because their presence may maximize spinal stability and impede any anterior displacement of the graft. The corpectomy is expanded until the contralateral pedicle is encountered, which signifies that a satisfactory decompression has been achieved, at which time the normal contours of the dural tube will be evident. 
As the cartilaginous end plates of the neighboring vertebrae are scraped off with an elevator in preparation for an arthrodesis, it is important not to violate the subchondral bone, which may diminish the biomechanical properties of the construct and lead to graft subsidence. The spinal column may either be reduced by opening a lamina spreader within the corpectomy defect, having an assistant manually apply an anterior vector force to the patient’s spine, or by distracting through anterior instrumentation; direct pressure on the apex of a kyphosis may yield even greater correction of any sagittal plane deformities. 
Since tricortical bone obtained from the patient’s iliac crest is the only interbody implant that provides all of the factors required for a successful fusion—namely, osteoblastic cells, osteoinductive signaling proteins, and an osteoconductive scaffold—autograft is still considered to be the “gold standard” for anterior reconstructions of the thoracolumbar spine. Given that the morbidity of these grafting procedures is not trivial, it is not surprising that several different strategies have been developed as potential replacements for autogenous bone such as humeral and tibial allografts as well as metal cages and other synthetic devices composed of polyetheretherketone (PEEK) or carbon fiber packed with a bone graft extender or local autologous bone. Osteogenic fillers that may be beneficial for eliciting a solid arthrodesis of the anterior column include demineralized bone matrices and recombinant human bone morphogenetic proteins (e.g., rhBMP-2). Unfortunately, the relative superiority of any one of these methods for this specific application has not been corroborated by comparative investigations. 
The designated interbody implant is filled with cancellous bone and carefully introduced into the corpectomy site without encroaching on the spinal cord, nerve roots, or blood vessels that are in close proximity to the anterior column (Fig. 45-28). Many surgeons elect to score the vertebral end plates so that the strut graft may be keyed into these grooves, but this technique may result in a greater degree of settling. This segment may be provisionally compressed by straightening the operating room table and discontinuing any distraction of the spinal column. 
Figure 45-28
Schematic drawings demonstrating the steps involved in the implantation of a strut graft for the subsequent reconstruction of the anterior column.
See text for operative technique.
See text for operative technique.
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The implementation of anterior instrumentation has risen dramatically in recent years because of their well-documented capacity for increasing the rigidity of the spine, which may translate into improved fusion rates and fewer graft complications; consequently, with contemporary screw and rod systems it is now reasonable to consider anterior-only constructs for certain thoracolumbar injuries. To avoid impinging on the great vessels located anterior to the spine, the “safe zone” for any internal fixation is limited to the posterolateral portion of the vertebral bodies (Fig. 45-29). Prominent osteophytes and other bony protrusions are leveled with a pituitary rongeur or burr, which permits the hardware to lie flush against the spinal column. After the screw holes are created across both the superior and inferior vertebrae, these implants are advanced with or without the aid of fluoroscopic guidance with the goal of not perforating the uninvolved disk spaces or projecting more than 1 to 2 mm beyond the far cortex if bicortical purchase is desired. Before securing the screws to a spanning plate or rod, additional compressive forces may be generated through the instrumentation, which may stimulate bony healing at the interface between the graft and end plates. 
Figure 45-29
 
A: Schematic drawing of an anterior construct consisting of an interbody graft within the corpectomy defect, which is spanned by a plate. B: Axial CT image demonstrating a metal cage filled with bone graft with instrumentation positioned on the lateral aspect of the spinal column.
A: Schematic drawing of an anterior construct consisting of an interbody graft within the corpectomy defect, which is spanned by a plate. B: Axial CT image demonstrating a metal cage filled with bone graft with instrumentation positioned on the lateral aspect of the spinal column.
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Figure 45-29
A: Schematic drawing of an anterior construct consisting of an interbody graft within the corpectomy defect, which is spanned by a plate. B: Axial CT image demonstrating a metal cage filled with bone graft with instrumentation positioned on the lateral aspect of the spinal column.
A: Schematic drawing of an anterior construct consisting of an interbody graft within the corpectomy defect, which is spanned by a plate. B: Axial CT image demonstrating a metal cage filled with bone graft with instrumentation positioned on the lateral aspect of the spinal column.
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Any ongoing bleeding from the bony surfaces or the soft tissues must be controlled with bipolar electrocautery or hemostatic substances before suturing together the ends of the parietal pleural. If necessary, an anatomic repair of the diaphragm is performed and a thoracostomy tube is ordinarily inserted to drain out any postoperative air or fluid collections. Once the ipsilateral lung is reinflated and the intercostal space has been sealed, the individual layers of the wound are closed separately. The preoperative and postoperative images of a thoracolumbar burst fracture that was addressed with an anterior corpectomy and arthrodesis with an interbody implant and supplementary instrumentation are presented in Figure 45-30
Figure 45-30
Imaging studies of a 27-year-old man who presented with progressive numbness and weakness in both lower extremities following a fall from a second-story window.
 
An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
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An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
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Figure 45-30
Imaging studies of a 27-year-old man who presented with progressive numbness and weakness in both lower extremities following a fall from a second-story window.
An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
View Original | Slide (.ppt)
An injury to the L1 vertebral body is evident on the initial anteroposterior (A) and lateral (B) radiographs. Sagittal computed tomography (C) and magnetic resonance (D) images demonstrate a burst injury with compression of the conus medullaris secondary to retropulsion of a bony fragment into the spinal canal. Postoperative anteroposterior (E) and lateral (F) views of the thoracolumbar junction obtained following a L1 corpectomy, insertion of an expandable titanium cage, and placement of anterior instrumentation.
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Postoperative Care

The chest tube is initially placed on suction until there is minimal drainage, and it is only pulled when there are no clinical or radiographic signs of a pneumothorax or air leak. Oral intake should be prohibited until flatus or bowel sounds have been recorded. As with those who have undergone posterior spinal procedures, patients whose thoracolumbar fractures have been treated through an anterior approach are managed with a regimen consisting of rapid mobilization and variable periods of bracing. Likewise, standing radiographs must be obtained at multiple time points so that any evidence of progressive deformity, graft subsidence or other findings consistent with a nonunion are not missed. 

Potential Pitfalls and Preventative Measures

In addition to those described above, pitfalls and preventative measures associated with anterior procedures are located in Table 45-6
 
Table 45-6
Pitfalls and Preventions for Anterior Surgical Techniques
Pitfalls Preventions
Incomplete decompression during corpectomy If the dural tube does not regain its normal convex appearance after corpectomy, the adjacent canal must be explored for sequestered fragments of disc or bone that may cause persistent neural compression.
A corpectomy is complete when the decompression extends transversely from pedicle to pedicle, as well as between both disc spaces.
Vascular injury Anterior instrumentation should be situated on the posterolateral vertebral body surfaces to avoid erosion into the great vessels, located along the anterior spinal column.
Anterior screws that protrude too far beyond the far cortex may lead to catastrophic vascular complications, either acutely or in a delayed fashion.
Placement of anterior instrumentation in the lower lumbar spine L4 or below is not advisable because of the potential hazards to the overlying iliac vessels.
Graft subsidence The interbody implant should be as large as possible to enhance load sharing, facilitate deformity correction, and reduce the risk of dislocation.
Anterior screws with bicortical purchase have greater pull-out strength and confer greater stability.
Stand-alone anterior constructs are contraindicated for: kyphosis >30 degrees, vertebral body collapse >50%, translation >2.5 mm, posterior ligamentous complex disruption.
Damage to the subchondral bone when removing cartilaginous endplates predisposes to graft settling. Similarly, subsidence may occur if slots are created in the vertebral bodies to seat the graft/implant.
The use of metallic interbody cages in elderly patients leads to a mismatch between the modulus of elasticity of these rigid devices and that of osteoporotic bone.
A small strut graft is more likely to migrate and may lead to nonunion with progressive kyphosis.
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Treatment-Specific Outcomes for Thoracolumbar Spine Fractures and Dislocations

Nonoperative Versus Operative Treatment

Dai et al.40 retrospectively reviewed a large series of 147 thoracolumbar fractures that occurred in conjunction with multiple other injuries. According to their analysis, the group that had been immobilized was significantly more likely to contract pneumonia and required longer hospital stays than the subjects who were managed with operative fixation. Shen et al.137 prospectively evaluated 80 neurologically intact patients with single-level burst injuries at the thoracolumbar junction who were either treated with a course of bracing or short-segment instrumented posterior arthrodesis. In this series, surgery brought about greater initial correction of kyphosis and earlier pain relief but at 24 months there were no significant differences between these two cohorts. Wood et al.168 also performed a randomized, prospective study comparing surgical and conservative treatments for stable burst fractures without any accompanying neurologic impairment. At an average follow-up of 44 months, operative stabilization of these injuries did not appear to provide any meaningful advantages to these individuals; in fact, those who were placed in a body cast or orthosis actually reported less disability, greater pain relief, and fewer complications. However, another recent prospective, randomized, multicenter trial supported the use of short-segment posterior stabilization for these types of fractures by showing that these procedures gave rise to decreased kyphosis, better functional scores, and a faster return to work relative to immobilization in a Jewett device.138 

Comparative Studies of Various Surgical Approaches of Thoracolumbar Spine Fractures and Dislocations

At this time, the superiority of one operative procedure over the others has yet to be borne out in the current literature. Two centers independently proposed that anterior decompression of burst fractures may generate more substantial improvements in neurologic status compared to indirect reduction of these injuries through a posterior approach.25,104 In another series of unstable burst fractures, an anterior corpectomy and instrumented arthrodesis were found to be more efficacious than posterior short-segment fixation for restoring normal sagittal alignment.133 While Been and Bouma16 also observed better deformity correction with circumferential surgeries than with posterior implants alone, the neurologic outcomes of these cohorts were equivalent. However, Danisa et al.41 identified no significant differences between patients with unstable burst injuries addressed anteriorly, posteriorly, or with a combined technique. Esses et al.48 conducted a prospective, randomized investigation in which subjects with acute thoracolumbar burst fractures were alternately treated with posterior distraction and pedicle screws or direct anterior decompression in conjunction with a fusion construct composed of an autogenous tricortical iliac crest strut graft and a screw-rod device. Although the authors noted no obvious disparities between the clinical and radiographic results of these two strategies, they emphasized that anterior operations permitted a more thorough decompression of the spinal canal. In a more recent prospective clinical trial, 38 patients with stable burst injuries located at the thoracolumbar junction and no attendant neurologic deficits were randomized so that they either underwent a posterior instrumented arthrodesis or an anterior reconstruction with an allograft strut and lateral fixation.167 At a minimum of 2-year follow-up, the fusion rates and functional outcomes of these two cohorts were comparable but there was a trend toward more frequent complications and a higher incidence of revision surgeries with a posterior approach. 

Management of Complications in Thoracolumbar Spine Fractures and Dislocations

Nonsurgical Complications in Thoracolumbar Spine Fractures and Dislocations

Given the severity of these injuries, it should come as no surprise that thoracolumbar fractures may give rise to a wide range of complications (Table 45-7). Although patients with obvious neurologic deterioration are usually treated with surgery in the acute setting, it is not uncommon for individuals who have sustained spinal trauma to experience increasing impairment secondary to other pathologic conditions such as a syringomyelia. Whether surgical stabilization is performed, the inherent instability of many thoracolumbar injuries also predisposes many of these patients to the development of spinal malalignment in any plane. In most cases, fractures that demonstrate kyphosis greater than 30 degrees, height loss greater than 50%, translation greater than 2.5 mm, canal compromise greater than 50%, or signs of posterior ligamentous disruption on MRI studies may be particularly susceptible to progressive deformity although these criteria are unvalidated. Because these fractures are frequently associated with injuries to the spinal cord and abdominal viscera, there is also a fairly high incidence of gastrointestinal abnormalities including ileus, gastroesophageal reflux disease, and constipation, all of which must be managed with appropriate interventions. Individuals with thoracolumbar fractures, especially those with concomitant SCIs, are clearly at risk for thromboembolic events; in one investigation, the rate of symptomatic deep vein thrombosis or pulmonary embolism was reported to be approximately 2%, with the incidence of asymptomatic clots estimated to be even higher.124 Consequently, some form of prophylaxis is indicated for these patients such as chemical anticoagulation, intermittent pneumatic compression devices, or vena cava filters. Despite the appearance of a healed fracture, a large proportion of this population will continue to complain of intractable pain, which may be refractory to both conservative and operative measures. Finally, these types of injuries regularly necessitate prolonged hospitalizations, which may lead to problems related to pneumonia, pressure ulceration of the skin, or malnutrition. 
Table 45-7
Common Complications Associated with Thoracolumbar Fractures
Type Complication/Adverse Event
Nonsurgical Progressive deformity after conservative treatment
Late neurologic deficit due to progressive deformity (rare)
Thromboembolic events, particularly for patients in spinal cord injury
Chronic pain regardless of fracture healing
Complications associated with prolonged hospitalization-–pneumonia, pressure ulcers, malnutrition
Surgical Neurologic deficits secondary to pedicle screw placement (∼1%) or fracture reduction
Surgical site infection (∼10%)
Durotomy related either to fractured bony fragments or iatrogenic injury
Surgical blood loss
Pseudarthrosis and progressive deformity
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Surgical Complications in Thoracolumbar Spine Fractures and Dislocations

While the surgical techniques that are used to decompress and stabilize thoracolumbar fractures are considered to be reasonably safe, these procedures may still subject the patient to a number of potential complications (Table 45-7). Iatrogenic neurologic insults have been shown to occur in 1% of posterior operations secondary to the erroneous placement of pedicle screws.82 Malpositioned implants may also bring about serious injuries to any number of visceral or vascular structures, which are often life threatening, especially when they are not diagnosed and addressed expediently (Fig. 45-31). Up to 10% of instrumented fusions for thoracolumbar fractures may become infected, all which require either long-term antibiotic therapy directed toward the causative organism or possibly open irrigation and debridement if indicated.127 Symptomatic durotomies should be repaired primarily if possible, but individuals with unrelenting leakage of cerebrospinal fluid from fistulas are routinely managed with protracted bed rest or even insertion of a lumbar subarachnoid drain to decrease intradural pressure enough so that a watertight closure may be obtained. Any remaining intersegmental instability at the arthrodesis site may result in the formation of a pseudarthrosis with hardware failure, recurrent deformity, and unrelenting pain (Fig. 45-32). Unfortunately, these surgical approaches are also not without their morbidity. Patients undergoing anterior or posterior procedures may experience substantial blood loss from a corpectomy or the epidural veins, compromised pulmonary function, or poor wound healing. 
Figure 45-31
 
Axial computed tomography image showing right pedicle screw that has been directed too laterally so that the tip protrudes beyond the vertebral body, increasing the risk of a potentially life-threatening injury to vascular or visceral structures.
Axial computed tomography image showing right pedicle screw that has been directed too laterally so that the tip protrudes beyond the vertebral body, increasing the risk of a potentially life-threatening injury to vascular or visceral structures.
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Figure 45-31
Axial computed tomography image showing right pedicle screw that has been directed too laterally so that the tip protrudes beyond the vertebral body, increasing the risk of a potentially life-threatening injury to vascular or visceral structures.
Axial computed tomography image showing right pedicle screw that has been directed too laterally so that the tip protrudes beyond the vertebral body, increasing the risk of a potentially life-threatening injury to vascular or visceral structures.
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Figure 45-32
 
Axial computed tomography image of a patient with a lumbar fracture treated with a posterior instrumented fusion construct, which reveals lucencies around the pedicle screws indicative of implant loosening and pseudarthrosis.
Axial computed tomography image of a patient with a lumbar fracture treated with a posterior instrumented fusion construct, which reveals lucencies around the pedicle screws indicative of implant loosening and pseudarthrosis.
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Figure 45-32
Axial computed tomography image of a patient with a lumbar fracture treated with a posterior instrumented fusion construct, which reveals lucencies around the pedicle screws indicative of implant loosening and pseudarthrosis.
Axial computed tomography image of a patient with a lumbar fracture treated with a posterior instrumented fusion construct, which reveals lucencies around the pedicle screws indicative of implant loosening and pseudarthrosis.
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An aging population means that greater numbers of osteoporotic patients, with a relatively high risk of instrumentation failure, will require spinal stabilization to treat unstable fractures. The relationship between failure of spinal instrumentation and variations in bone mineral density (BMD) has been described. Halvorson et al.68 described the effect of osteoporosis on the pullout force of pedicle screws in cadaveric spines. Spines with normal BMD had pullout strength that was more than seven times higher than the force needed for uniaxial screw failure in osteoporotic bone. Although the magnitude of the effect varied from study to study, Burval et al.,27 Cook et al.,36 and Coe et al.35 found similar relationships between the forces required to cause pullout of pedicle screws in osteoporotic versus normal bone. Cancellous bone density is a primary determinant of the strength of screw fixation in vertebral bodies,60 the portion of bone most severely affected by postmenopausal osteoporosis. Similarly, BMD has an important effect on the results of interbody fusion in patients with osteoporosis. Predictably, subsidence rates are higher with decreased BMD.123 The use of posterior instrumentation and techniques such as cement augmentation of pedicle screw fixation may help to confer stability and avoid graft or cage subsidence in the setting of poor bone quality.123,142 Intuitively, a broader base of support may be helpful in distributing load across a wider footprint; this concept has been demonstrated in clinical investigations by Le et al.95 who demonstrated lower subsidence rates when interbody cages with greater endplate surface area were used. Consideration of the effect of BMD is essential in the preoperative planning stages of treatment for patients with osteoporosis who require spinal fusion after traumatic injury. 

Authors’ Preferred Treatment for Thoracolumbar Spine Fractures and Dislocations

 
 

Following the algorithm described in TLICS (Fig. 45-33), the TLICS score (Table 45-1) is calculated by considering fracture morphology, the integrity of the PLC and the patient’s neurologic status. Patients with scores of 3 or less are treated nonoperatively whereas those with scores of 5 or higher are treated with surgical stabilization and fusion. Patients with a score of 4 will be treated with a trial of nonoperative treatment if they do not have a PLC injury or neurologic deficit whereas those with either a neurologic injury or PLC injury should be stabilized expediently to optimize the likelihood of neurologic recovery and minimize the risk of secondary displacement due to ligamentous instability.

Rockwood-ch045-image033.png
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Figure 45-33
TLICS score algorithm.
Rockwood-ch045-image033.png
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Controversies and Future Directions in Thoracolumbar Spine Fractures and Dislocations

Timing of Surgery of Thoracolumbar Spine Fractures and Dislocations

For patients with ongoing neurologic decline, it is generally accepted that prompt operative intervention may yield superior clinical outcomes.31 In animals, rapid decompression appears to correlate with enhanced neurologic recovery but these benefits have not necessarily been recorded in humans.29 However, the optimal time to perform surgical procedures in individuals who are neurologically intact is still a controversial issue. The authors of one retrospective study observed a trend toward greater return of neurologic function among a group of thoracolumbar fractures that were addressed surgically within 8 hours of the traumatic event compared to injuries in which these operations were completed in a delayed fashion, but otherwise there were no significant time-dependent effects identified in this series.53 In a similar investigation, Chipman et al.32 concluded that even though early surgery did not provide any additional improvements in terms of postoperative neurologic status, patients that were treated less than 3 days after sustaining their fractures exhibited significantly fewer complications and shorter hospitalizations than others whose interventions occurred after this point. Based on this limited data, patients with thoracolumbar fractures who do not exhibit neurologic compromise requiring emergent decompression may be carefully evaluated before any type of operation; for instance, it may be prudent to postpone definitive surgical stabilization until any hemodynamic instability has been corrected and traumatic injuries to all other organ systems have been thoroughly ruled out (e.g., cardiac, pulmonary). 

Minimally Invasive Surgical Techniques of Thoracolumbar Spine Fractures and Dislocations

Minimally invasive spinal surgery (MISS) has become increasing popular in recent years because of its potential for decreasing operative morbidity and preserving the stability of the vertebral column, which many advocates claim may translate into improved long-term functional outcomes. Many of these purported advantages are still largely theoretical and have not been supported by any randomized, prospective, controlled clinical trials comparing MISS with open techniques. Nevertheless, the rationale for MISS is undoubtedly intuitively pleasing to surgeons and patients alike. While MISS may be inappropriate for many thoracolumbar fractures, such as those that are associated with a substantial amount of canal occlusion and an incomplete neurologic injury, the feasibility of MISS for thoracolumbar trauma has already been preliminarily established. One center has reported their considerable experience with endoscopically assisted anterior corpectomy, interbody reconstruction, and instrumentation for thoracolumbar fractures.17,87 While the initial results have been favorable, the authors concede that this strategy is very difficult and entails a very steep learning curve. 
Another MISS procedure that is currently under investigation includes the use of vertebroplasty or kyphoplasty for traumatic thoracolumbar injuries, either with1,2,34,89,90,156 or without supplemental fixation42,152 (Fig. 45-34). One major concern regarding the injection of cement into a fractured vertebral body with disruption of the posterior cortex is the possibility that this material may extrude into the canal and produce an iatrogenic neurologic deficit. Clearly, multiple well-designed studies are warranted to confirm the safety and efficacy of this and other surgical techniques for the treatment of the entire spectrum of thoracolumbar spinal injuries. Vertebroplasty and kyphoplasty may also be used to treat vertebral compression fractures in older patients. The treatment of vertebral compression fractures related to osteoporosis is a challenging clinical and public health problem because of their high incidence in the elderly population. While often asymptomatic, these fractures can cause a substantial reduction in vertebral body height and multiple fractures in the same region of the spine may lead to pronounced kyphosis, back pain and disability. Vertebral compression fractures may be surgically treated by interventional techniques utilizing cement to stabilize injured vertebral bodies such as kyphoplasty or vertebroplasty130,159 which have been shown to reduce pain. Kyphoplasty has been additionally shown to aid in sagittal deformity correction and prevention of kyphosis through the use of an air tamp to restore vertebral height prior to cement injection. Well-publicized recent randomized controlled studies, however, have brought the efficacy of these techniques into question26,79 as they have demonstrated no benefit to vertebroplasty in terms of improvement in back pain or in the Roland-Morris Disability Quotient comparing patients treated with vertebroplasty or a sham procedure. Although these studies have been criticized for enrolling a low percentage of eligible patients and the lack of imaging to determine fracture acuity, further investigation is necessary to elucidate the appropriate clinical role for these treatments. 
Figure 45-34
 
Postoperative anteroposterior (A) and lateral (B) radiographs demonstrating postoperative images after compression injuries of T12 and L1 were treated with kyphoplasty, a technique in which cement is injected percutaneously to attempt to restore vertebral body height loss created by the fracture.
Postoperative anteroposterior (A) and lateral (B) radiographs demonstrating postoperative images after compression injuries of T12 and L1 were treated with kyphoplasty, a technique in which cement is injected percutaneously to attempt to restore vertebral body height loss created by the fracture.
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Figure 45-34
Postoperative anteroposterior (A) and lateral (B) radiographs demonstrating postoperative images after compression injuries of T12 and L1 were treated with kyphoplasty, a technique in which cement is injected percutaneously to attempt to restore vertebral body height loss created by the fracture.
Postoperative anteroposterior (A) and lateral (B) radiographs demonstrating postoperative images after compression injuries of T12 and L1 were treated with kyphoplasty, a technique in which cement is injected percutaneously to attempt to restore vertebral body height loss created by the fracture.
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