Historical Perspective

Surgical management of thoracic spine fractures before introduction of the Harrington internal fixation system in the 1960s was limited to laminectomy and often associated with neurological deterioration secondary to spinal cord manipulation or increased instability.³ However, the success of surgical treatment of thoracic fractures has grown in parallel with technologic advancements in spinal instrumentation. Krengel and colleagues were among the first to demonstrate that early stabilization plus decompression of incomplete thoracic spinal cord injuries was associated with improved neurological function.⁴ Further data have suggested that early internal fixation may decrease hospital stay, prevent bony deformity, and accelerate transfer to rehabilitation.⁵

The past 2 decades have witnessed a shift away from hook constructs as pedicle screw systems have been shown to be a safe, reliable, and biomechanically superior choice for internal fixation in the thoracic spine.^6–8 The presumed clinical benefit of operative intervention continues to be the impetus behind surgical intervention despite a lack of class I evidence. As the emphasis on evidence-based clinical decision making continues, new methods of comparison have been championed to supplant the costly, lengthy, and often impractical randomized trial in the traumatic spine patient population. Recently, a novel parallel cohort study with blinded inclusion based on clinical equipoise was used to compare operative and nonoperative treatment strategies for traumatic lumbar and thoracic fractures; a trend toward better neurological recovery, although not reaching statistical significance, was found in the operative group.⁹

Epidemiology

Thoracic spine fractures are relatively rare in comparison to fractures of the cervical, lumbar, and thoracolumbar regions; in a large multicenter study, only 16% of spinal fractures occurred in the T1-10 region.¹⁰ A wedge compression fracture is the most common thoracic spine injury, and multiple noncontiguous fractures in the thoracic spine are not rare. Spinal cord injury accompanies about 10% of thoracic vertebral body injuries, as opposed to a 39% incidence of concurrent spinal cord injury seen with cervical injuries.¹¹ Approximately 15% of all spinal cord injuries occur in the thoracic spinal cord, and 17% of upper thoracic spine injuries cause paraplegia.^12–14

The midthoracic spine is the most rigid and consequently at increased risk for fracture; the upper thoracic and T10 levels are less frequently injured, as noted later. The high-energy impacts causing thoracic spine fractures can generate severe concomitant injuries, including dissection or rupture of the aorta, intra-abdominal solid organ injury, hemothorax, pulmonary contusion, esophageal perforation, thoracic duct injury with chylothorax, and tracheal injury (Fig. 318-1).^15–17 Thoracic fracture-dislocations are very unstable and lead to complete paraplegia in 80% of patients; however, there have been several well-documented reports of neurologically intact patients in whom accompanying bilateral pedicular fractures caused autodecompression and spared the spinal cord.¹⁸

FIGURE 318-1 Coronal computed tomographic reconstruction of traumatic disruption of the thoracic spinal column in a patient who also sustained a concomitant rupture of the thoracic aorta after a high-speed motor vehicle crash with ejection.

Anatomic and Biomechanical Considerations

The thoracic spine consists of 12 vertebral bodies aligned in a prominent kyphotic curvature. These load-bearing elements of the spinal column are 2 to 3 mm shorter in anterior body height than in posterior body height.¹⁹ This is the primary cause of the normal kyphotic curve. There is also a dorsal arch that consists of relatively small pedicles, transverse processes, articulating facets, broad laminae, and a downward-pointing spinous process. The center of gravity of an upright individual falls through the anterior body of T1, passes anterior to the thoracic spine, and falls through the midbody of T12 (Fig. 318-2).

FIGURE 318-2 Schematic drawing of the spinal column with the center of gravity drawn. Note that the upper thoracic vertebral bodies (T1-10) are posterior to the line of gravity. This causes a flexion moment to be placed on this portion of the spinal column under normal conditions and is an important consideration when using fixation instrumentation to treat fractures of the thoracic bony column.

In the upper levels of the thoracic spine, the facets are coronally oriented, whereas at the lower levels, they are sagittally oriented. These characteristics result in the facets of the upper thoracic levels rendering little resistance to rotational forces while offering significant resistance to anterior translation. The opposite is seen in the lower thoracic levels, where the more lumbar-like orientation of the facet joints limits rotation and has little resistive effect on translation. The facet joints also absorb compressive forces while offering resistance to flexion loading.

The thoracic spine is connected to the rib cage by body and transverse process articulations to individual ribs. The rib cage restricts the motion of the thoracic spinal column—especially in extension, which is reduced by 70%. The effects of the rib cage on flexion and lateral rotation are less prominent. The rib cage also adds stiffness to the spine, and experimental data have demonstrated a fourfold increase in tolerance of the spinal column to compression with an intact rib cage. Stabilization of the thoracic spine by the rib cage results in greater force being required to disrupt the spinal column at these levels than in other regions of the spinal column.²⁰

Normal motion of the thoracic spine is a function of the multiple elements that constitute the thoracic spinal column and the associated rib cage. The rigidity of the rib cage and orientation of the facet joints are addressed previously. The ribs limit flexion and extension of the upper thoracic area, whereas the posterior elements also resist extension. Axial rotation, in contrast, is limited by the rib cage, ligamentum flavum, facet capsules, and the anterior and posterior longitudinal ligaments. Removal of the posterior elements also has significant effects on motion of the thoracic spine. Hyperflexion is resisted by the rib cage, the anulus of the disk, the ligamentum flavum, and the posterior longitudinal ligament. The anterior longitudinal ligament and the rib cage resist extension.

The net result of the aforementioned anatomic considerations is that the mean of the range of flexion and extension at each segment in the upper thoracic spine is 4 degrees whereas that of the midthoracic spine is 6 degrees. The range of lateral bending is 6 degrees of motion per segment, whereas the range of axial rotation is 8 to 9 degrees.²¹ The rigidity of the midportion of the thoracic spine apparently places the midthoracic levels at increased risk for fracture. The upper thoracic and T10 levels are the most infrequently injured levels of the thoracic spine because they are protected by the adjacent, flexible cervical and thoracolumbar junctions (Fig. 318-3).²²

FIGURE 318-3 Distribution of thoracic fractures from T1 to T10 in a series of 1445 patients with spinal fractures.²²

Spinal Instability

Clinical instability is loss of the ability of the spine to maintain its pattern of displacement under physiologic loads so that there is no initial or additional neurological deficit, no major deformity, and no incapacitating pain.²³ Although this definition is very inclusive, it has rather limited utility to a clinician faced with an acutely injured patient.

Various authors have tried to define stability and then recommend treatment based on the presumed injury mechanism. In 1949, Nicoll attempted to define stable versus unstable fractures by using an anatomic classification based on analysis of a series of 166 fractures or fracture-dislocations of the thoracolumbar spine. In his view, the major determinant of stability was the integrity of the interspinous ligament.²⁴

Holdsworth introduced the first modern classification of fractures and attempted to use radiography to identify specific patterns of spinal fractures associated with the development of early as well as late instability.²⁵ This classification scheme is based on the two-column theory of spinal column stability and is essentially a biomechanical interpretation of the injury mechanisms determined by a review of plain radiography. The integrity of the posterior bony elements and the posterior ligamentous complex, including the interspinous and supraspinous ligaments and the ligamentum flavum, is the major determinant of stability. A flexion-rotation injury is the most unstable of spinal column injuries in this classification scheme because both the bony and ligamentous elements of the posterior spinal column are compromised. Holdsworth acknowledged that this system was flawed and that it did not predict the presence of an unstable subset of compression fractures.²⁵

Disruption of the posterior ligamentous structures alone, as posited by Nicoll and Holdsworth, is an insufficient view of instability of the spinal column. Denis modified the two-column theory of Holdsworth by dividing the anterior column into an anterior and a middle column, the latter consisting of the posterior longitudinal ligament and the posterior third of the vertebral body (Fig. 318-4).²⁶ He used computed tomography (CT) of the spinal column injury to establish the integrity of the middle column. The more common anterior wedge compression fracture is distinguished by continuity of the posterior cortical rim from one pedicle medially over the posterior vertebral body to the opposite pedicle. If what appears to be a compression fracture also features disruption of the posterior vertebral body, it is actually a burst fracture (Fig. 318-5). The integrity of the middle column became the basis of a new classification of spinal stability, with injury to the anterior and the middle or the posterior and the middle columns resulting in an “unstable” fracture.

FIGURE 318-4 Schema depicting the three-column model of spinal stability of Denis. Denis argued that the middle column (posterior longitudinal ligament, posterior anulus fibrosus, and posterior third of the vertebral body) must be disrupted in addition to the posterior ligamentous complex to create acute instability.

FIGURE 318-5 A, Computed axial tomography of a T5 compression fracture distinguished by an intact posterior wall of the vertebral body and the medial cortex of the pedicles (arrowheads). B, Similar scan of a T10 burst fracture with fragmentation of the posterior vertebral body (arrow).

The most comprehensive classification scheme was published in 1994 by Magerl and associates, whose initial report described 53 distinct fracture patterns.²² The classification system of Magerl is based on the mechanism of failure of the spinal column and is accepted, with modifications, as a research tool by members of the major spine societies. The main categories in the Magerl system are type A, compression injuries; type B, distraction injuries; and type C, multidirectional torque injuries with translation (Fig. 318-6).²⁷ These types are ordered in terms of increasing severity of the resultant spinal column injury and subdivided into groups according to the injury mechanism. The division into three groups is based on the morphologic features of the injury and the severity of the injury as it progresses through both the types and the groups, the most stable being an A1 fracture and the least stable being C3. Although the original classification contains further subdivisions, the simplified system reported by Gertzbein stops at the 3-by-3 grid (Fig. 318-6).²⁷

FIGURE 318-6 Fracture classification system as proposed by Magerl and coworkers and modified by Gertzbein. Fractures are divided into types according to major injury force: A1 to A3, compression; B1 to B3, distraction; and C1 to C3, multidirectional with translation (see text for details). The classification system is arranged in order of increasing severity: A1 is the most stable, whereas C3 is the least stable. The classification system can be used to determine the need for instrumentation and the optimal type of fixation. It represents a uniform method of classification of fractures for clinical research.^22,27

Although perhaps useful in the research setting, the Magerl system has been criticized as being too complex for routine clinical use and has performed poorly in tests of interobserver agreement.^28,29 Furthermore, although the Denis model remains popular, its original tenet—that instability ensues when two of the three columns are disrupted—has been recognized as an oversimplification that fails to incorporate the biomechanical importance of the spinal ligaments.

With spinal experts agreeing that most thoracolumbar fractures can be managed conservatively, the ideal classification system would be easy to apply, be highly reproducible, and assist in identifying the minority of patients who would benefit from operative intervention. This need for a practical thoracolumbar classification system directly linked to a clinical decision-making algorithm prompted the Spine Trauma Study Group to develop the thoracolumbar injury classification and severity score (TLICS).^30,31 The TLICS scale is a point-based system founded on the triad of injury mechanism/morphology, integrity of the posterior ligamentous complex, and neurological status of the patient (Table 318-1).³² The total number of points is calculated for each thoracolumbar fracture based on these three major categories, and the final score is linked to an algorithm to help guide management: injuries with a total TLICS score of 3 or less should be considered for primary nonoperative management, fractures with a total TLICS score of 4 may be treated operatively or nonoperatively at the surgeon’s discretion, and injuries with a total TLICS score of 5 or higher should undergo primary operative management.³⁰ Further studies have shown that TLICS exhibits excellent validity and interobserver reliability, unlike older classifications.^33–35 By shifting emphasis away from the nebulous concept of spinal stability in favor of a quantitative assessment of operative necessity, the Spine Trauma Study Group has designed a seemingly robust classification that has thus far successfully met several stepwise validation challenges. Future studies will reveal whether the TLICS algorithm becomes widespread and whether the fracture score and its associated management recommendation are correlated with patient outcomes.

TABLE 318-1 Thoracolumbar Injury Classification and Severity Score

The maximum score is 10. Treatment recommendation: total score of 3 or less, nonoperative treatment; total score of 4, surgeon discretion regarding nonoperative versus operative treatment; total score of 5 or higher, operative treatment.

Mechanism of Injury

Surgical therapy for an injured thoracic spine must take into account the injury force or forces that acted on the bony column and the pattern of instability associated with the specific injury. The forces responsible for a spinal column injury are generally accepted as compression, flexion, extension, rotation, shear, distraction, or a combination thereof.³⁶ Magerl and colleagues formulated a classification system by dividing the pathomorphologic characteristics of the action of injury moments into three patterns: compressive, tensile/distractive, and axial torque, which correspond to the three injury types in the system—A, B, and C, respectively (Fig. 318-6).²²

The combination of plain radiography, CT, and magnetic resonance imaging (MRI) allows definition of the bony and ligamentous injuries that have been inflicted. The information from these studies allows classification of the injury, identification of unstable injuries, and selection of the proper instrumentation to stabilize the unstable spinal column elements adequately.

Compression or Axial Loading Fractures

The normal kyphosis of the upper thoracic spine results in an axial compression load being converted into an anterior flexion load on the vertebral body. The resultant fracture of the vertebral body is a wedge compression fracture; the same injury is produced by a flexion vector (Fig. 318-7).³⁶ Magerl classified these fractures as types A1 to A3, depending on the injury pattern.

FIGURE 318-7 A flexion injury vector causes anterior compression of the vertebral body. The resultant injury is usually a stable wedge compression fracture (Magerl type A1). If tension on the posterior elements is sufficient and the ligamentous structures fail, an unstable compression fracture results. When there is axial loading in addition to the flexion vector, the posterior body fails in a characteristic manner and produces a burst fracture (Magerl type A3).

Shear

Shear forces can be directed in any direction along the longitudinal axis of the spine (Fig. 318-8). Roaf demonstrated that shear force can produce severe ligamentous disruption similar to that generated by the combination of flexion and rotation considered earlier.³⁸ Shear forces acting in a posterolateral direction cause the superior vertebral body to sublux anteriorly on the inferior vertebral body, with a complete spinal cord injury resulting from movement of the vertebral bodies. There have been occasions when anterior movement of the superior body results in disruption of the pars interarticularis or the pedicles, thereby “decompressing” the spinal cord and protecting it from serious injury.³⁹ The more common result of this load is an anterior spondylolisthesis; however, the anterior body can be displaced posteriorly or laterally on the inferior body. The Magerl classification of this fracture pattern is type C1.

FIGURE 318-8 A shear injury is the result of injury vectors directed in opposite directions on different levels of the spinal column. The resultant injury is highly unstable because of damage to all three columns of the spine. In addition to anterolisthesis and retrolisthesis, displacement may be in a lateral direction, depending on the exact direction of the offending vectors. The resultant injury pattern is a Magerl type C1 fracture or a type C3 fracture if the injury vectors are in the coronal plane.

Flexion-Distraction

Although this type of injury was first described radiographically by Chance in 1948,⁴⁰ the mechanism of injury was not defined until later.⁴¹ These injuries are commonly associated with the use of seat belts, especially lap belts, were once called seat belt injuries, but are more appropriately designated flexion-distraction injuries. Denis distinguished between “seat belt–type” injuries, of which the fracture described by Chance is only one, and fracture-distraction injury, which is a subtype of fracture-dislocation injury.²⁶ Although the mechanism of injury is similar in both injuries, that is, a flexion movement produces a tensile force on the posterior and middle columns that acts on an axis of rotation and is translated anteriorly (by a seat belt holding the anterior abdominal wall to the seat), the latter injury is characterized by failure of the anterior column along with disruption of the anulus and stripping of the anterior longitudinal ligament from the inferior vertebral body. Loss of the anterior column allows anterior spondylolisthesis to develop. Although none of the fracture-dislocations of the flexion-distraction type occurred in the upper thoracic levels in the series reported by Denis, Eismont and associates stated that flexion-distraction can result in a bilateral facet dislocation in the thoracic spine.^26,36 The fracture described by Chance is designated type B2 in the Magerl classification system, whereas fracture-distractions involving ligamentous disruption of the posterior column are designated type B1 (Fig. 318-9).²²

FIGURE 318-9 The flexion-distraction injury vector is responsible for the seat belt injuries first described by Chance in 1948. Note that the axis of rotation is displaced anterior to the longitudinal axis of the bony column, and therefore the spinal column is under tension. In the upper thoracic spine, this injury vector can result in bilateral facet dislocation. The resultant injuries are classified as Magerl type B1 or B2 fractures.

Extension

The vector in this injury is the opposite of the flexion vector acting on the trunk, and it results in forced posterior movement. Although the majority of the injuries resulting from this force are isolated fractures of the posterior elements (facet, lamina, or spinous process), if a severe force is applied, the anterior longitudinal ligament and anulus will fail and result in a highly unstable shear fracture because retrolisthesis of the superior vertebral body on the inferior vertebral segment can occur. Denis and Burkus reported 12 of these types of fractures, 7 of which were in the upper thoracic spine, in a report after Denis’ original paper (Fig. 318-10).⁴² The Magerl classification of this fracture type is type B3.

FIGURE 318-10 If an injury vector is directed posteriorly on the upper portion of the thoracic spine, the resultant hyperextension of the spinal column can cause failure of the anterior longitudinal ligament in tension and the posterior elements in compression. The resultant injury can be highly unstable and is classified as a Magerl type B3 fracture.

Flexion-Rotation

This combination of injury vectors produces an extremely unstable injury of the vertebral column (Fig. 318-11). The flexion load causes an anterior vertebral body compression fracture, whereas the rotational load disrupts the facet joints by fracturing the superior facet on one side and tearing the facet capsule on the other. In addition, the anulus may fail, the posterior ligaments are disrupted, and the posterior vertebral body may fracture, with retropulsion of bone into the canal. The fracture-dislocation that results from this combination of load on the vertebral column was recognized by Holdsworth in his original paper as a highly unstable fracture that was “so constantly associated with paraplegia.”²⁵ Magerl and colleagues classified this fracture as type C3, the most unstable fracture in their classification system.²²

FIGURE 318-11 The combination of flexion and rotation injury vectors is more likely to produce serious spinal column and cord injuries than those associated with only a flexion injury vector. This combination of injury vectors renders the posterior ligamentous structures and joint capsules incompetent and obliquely disrupts the anterior vertebral body and the associated disk. The injury pattern is classified as a Denis type D burst fracture or a Magerl type C3 injury.

Initial Management of a Thoracic Spine Injury

After the patient is immobilized in the field with a collar and hard board and stabilized in accordance with the advanced trauma life support guidelines, the primary survey is conducted by the trauma team, including palpation of the entire posterior spinal axis to detect any bony step-off (and tenderness if the patient is responsive) during a logroll procedure to remove the hard board. In a modern trauma center, the initial thoracic spine imaging is typically generated as reconstructed images from thoracoabdominal CT scans in patients with a sufficient mechanism or clinical concern for spinal trauma. Any spinal fractures or bony displacement seen on such reconstructed CT images triggers neurosurgical consultation. Although trauma to the posterior ligamentous complex may be inferred from bony imaging findings such as splaying of the spinous processes on CT, MRI is performed for all thoracolumbar fractures as the preferred modality to assess the spinal ligaments.⁴³ MRI is ordered on an emergency basis when the neurological examination reveals a focal motor or sensory deficit or if there is a history or signs of bowel/bladder dysfunction (e.g., elevated postvoid residual). The prevalence of wrong-level operations in the thoracic spine is significant,⁴⁴ and we therefore insist on concomitant lumbar imaging so that one can count up from the sacrum to localize the thoracic pathology.

All patients with a neurological deficit from a spinal fracture undergo a physician-documented neurological examination based on the American Spinal Injury Association (ASIA) Standard Classification of Spinal Cord Injury Scale, which has very good interrater reliability.^45,46 Although an ASIA score is documented on admission, many subsequent scores are obtained because evidence demonstrates that the first ASIA score with prognostic capability occurs at 72 hours after injury. The use of high-dose intravenous methylprednisolone for acute spinal cord injury is highly controversial, and many centers are moving away from the practice.^47,48 An important consideration—which remains at the level of option—is that patients with an acute spinal cord injury should be monitored in the intensive care unit with a minimum mean arterial pressure goal of 85 to 90 mm Hg and adjunctive use of vasopressors to limit spinal cord hypoperfusion.^49,50

Surgical versus Nonsurgical Management

Since the introduction of Harrington distraction rods, enthusiasm has been growing for surgical treatment of thoracic fractures. This is due in part to the ongoing introduction of effective internal fixation technology and the perceived clinical benefits of operative spinal stabilization, such as early mobilization of the patient. Another impetus for surgery is to prevent neurological deterioration, chronic pain, or the development of spinal deformity. Before the TLICS scale (see earlier), classification systems for thoracic and lumbar fractures provided minimal assistance in helping physicians decide between nonoperative and operative management. With surgeons clinging to the simple dictum that instability merits operative intervention, broad definitions of instability, such as that of White and Panjabi, have become popular ways to encompass the concept that surgery for thoracic and lumbar fractures not only immediately protects the neuraxis but also provides prophylactic protection from future deformity, pain, or deficit. As noted earlier, White and Panjabi defined clinical instability as loss of the ability of the spine to maintain its pattern of displacement under physiologic loads so that there is no initial or additional neurological deficit, no major deformity, and no incapacitating pain.²³

The results reported by Frankel and associates remain the “gold standard” for nonoperative therapy to which alternative treatments and final outcomes are measured; in 371 patients with thoracic and lumbar fractures, there was only a 0.5% incidence of neurological worsening in those treated by postural reduction and recumbency.⁵¹ Similarly, excellent results with long-term follow-up are available for nonoperatively treated burst fractures of the thoracic and lumbar spine (primarily the thoracolumbar junction), with or without neurological deficit.^52–57 However, other series have demonstrated a much higher rate of neurological worsening during nonoperative treatment, such as the 18% incidence reported by Denis and coauthors.⁵⁸ Moreover, a thoracic or lumbar burst fracture—particularly one with a rotational component—has been associated with a higher risk for early neurological deterioration, even while patients are still hospitalized.⁵⁹

Whether surgery for patients with a thoracic fracture and spinal cord injury can increase the likelihood of neurological improvement remains a matter of debate. Neurological improvement of incomplete spinal cord lesions after anterior or posterior surgical decompression has been reported.^60–63 Krengel and colleagues favored early posterior decompression and instrumented fusion and demonstrated that surgery was safe and improved neurological recovery in comparison to historical controls managed nonoperatively or by late surgical intervention.⁴ With a focus on incomplete upper thoracic injuries, Bohlman and coauthors reported an improvement of 2.0 Frankel grades per patient with anterior surgical decompression.⁶⁴

Although two randomized prospective studies have compared operative with nonoperative management of neurologically intact patients with thoracolumbar burst fractures, there are no comparable studies for thoracic fractures.^65,66 The multiple hurdles encountered when performing randomized trials involving surgical intervention have prompted some to explore novel methods of cohort comparison in the trauma population. Most recently, Stadhouder and coworkers performed a parallel cohort study based on clinical equipoise in which operative and nonoperative treatment of traumatic thoracic and lumbar fractures were compared. With a mean follow-up of 6.2 years, pain scores, disability indices, and general health outcomes were comparable between the two groups; however, there was a nonstatistically significant trend toward better neurological recovery in the surgical group.⁹

The preponderance of evidence points to the importance of restoring anatomic alignment. Whitesides was adamant that persistent or progressive kyphosis inhibited neurological recovery.²⁰ In their studies of fractures of the thoracolumbar junction, Shuman, Jacobs, and colleagues found a direct correlation between progressive posttraumatic kyphosis and progression of neurological symptoms.^67,68 Similarly, in a follow-up study of patients with unstable thoracic and lumbar fractures, Soreff and associates showed a significant correlation between spinal deformity and symptomatology, and Edwards and coworkers’ data on patients with posttraumatic paraplegia suggested that anatomic restoration was important for good long-term results.^69,70 Nevertheless, Nicoll did not find any link between the degree of spinal deformity and symptoms, and McAfee and colleagues, in reviewing anterior decompression and fusion in patients with incomplete deficits, found that residual kyphosis did not preclude neurological improvement.^24,71 In the absence of cystic degeneration of the spinal cord, neurological deterioration in the setting of spinal deformity has been associated with progressive kyphosis, stenosis, arachnoiditis, and spinal cord tethering.⁷² The potential morbidity of untreated deformity and the increased neurological risks encountered with delayed surgical management have caused some to argue that long-term outcomes may be more satisfactory when posttraumatic deformity is corrected with earlier surgical intervention.⁷³

Nonoperative management of most thoracic and lumbar fractures has been fairly successful and almost as heterogeneous as surgical interventions—bed rest alone versus some combination of postural reduction, bracing, casting, early mobilization, and physical therapy.^52,74–76 Most of the bracing literature focuses on treating thoracolumbar junction fractures with thoracolumbosacral orthoses (TLSOs). Some have argued that many thoracic fractures do not require bracing because an intact rib cage and sternum will splint the affected portion of the spinal column. Occasionally, fractures of the upper thoracic spine are braced by obtaining purchase from the cervical spine via mandible or occipital pads or with a halo ring; such braces are categorized as cervicothoracic orthoses or cervicothoracolumbosacral orthoses.² Unstable, purely upper thoracic spine fractures have been successfully treated with orthotic bracing alone; in one series of 49 patients with upper thoracic fractures treated with bracing, no failure of arthrodesis was seen, yet complications included 1 case of neurological worsening, 8 cases of brace-related skin necrosis, and 12 cases of deep venous thrombosis.⁷⁷

Clearly, the risk for complications must also weigh into the decision of whether to proceed to the operating room. Gertzbein and associates, in a large multicenter study of 1019 thoracolumbar fractures, found a complication rate of 3% in the nonoperative group and 25% in surgically managed patients.¹⁰ However, one must be wary of such comparison studies given the lack of randomization and the realization that surgery is usually offered to patients with more severe injuries and neurological deficits. Proponents of surgery argue that it facilitates mobilization and rehabilitation. There is evidence that hospitalization time can be shortened with surgical stabilization in patients with thoracic and lumbar fractures causing paralysis.^78–80

There is no consensus regarding therapy for an individual thoracic spine injury, and indeed, several equivalently efficacious treatment alternatives are often available. Our philosophy is that good results can be achieved with more than one approach but that there are several guidelines that may be of assistance in the selection of a particular approach to a given fracture.

Although attempts have been made to correlate the degree of kyphosis, percent decrease in anterior vertebral body height, and amount of canal compromise from a retropulsed bone fragment with the degree of stability, no consensus exists. Most surgeons would agree with decompression and stabilization of neurologically incomplete spinal cord injuries, but consensus on the exact procedure or procedures, the order, and the timing of the surgical intervention remains elusive. The role of surgery in patients with complete spinal cord injuries is more controversial. We aggressively treat complete lesions with posterior stabilization to facilitate transfer to the spinal cord rehabilitative center unless significant anterior column damage exists.

Mirza and associates offer specific treatments for spinal fractures based on the classification of McAfee and colleagues and the presence or absence of a neurological injury. The specific recommendations are based on the authors’ collective experience and represent more traditional, principally orthopedic approaches to the treatment of spinal fractures. The recommendations have not been scientifically validated (Table 318-2).^81,82

TABLE 318-2 Treatment Guidelines as Identified by Mirza and Associates

HTLSO, hip thoracolumbosacral orthosis; TLSO, thoracolumbosacral orthosis.

Modified from Mirza SK, Mirza AJ, Chapman JR, et al. Classification of thoracic and lumbar fractures: rationale and supporting data. J Am Acad Orthop Surg. 2002;10:364.

Surgical Management of Thoracic Injuries

Surgical Approaches for Thoracic Fractures

The surgical options for thoracic spine fractures requiring operative stabilization fall into four basic categories: anterior/anterolateral transthoracic procedures, short-segment posterior fixation, long-segment posterior fixation, and combined anterior/posterior (the so-called 360-degree) approaches (Fig. 318-12).

FIGURE 318-12 The four basic instrumentation techniques for thoracic spinal trauma. A, Anterior-only approach with corpectomy, a strut graft, and a lateral screw-plate construct for a burst fracture. B, Short-segment posterior spinal fixation for a burst fracture without posterior ligamentous disruption. C, Long-segment posterior spinal fixation in a 23-year-old woman who sustained a lower thoracic fracture-dislocation and an American Spinal Injury Association (ASIA) type C incomplete spinal cord injury. D, Combined anterior-posterior instrumentation in a 22-year-old man who sustained T7 and T8 burst fractures and an ASIA type A complete spinal cord injury in a motocross accident.

Several groups have attempted to put forth a basic set of recommendations for selection of the surgical approach to thoracic spinal trauma. None are rooted in level I evidence, nor does any represent consensus in the field. The choice of surgical approach is ultimately contingent on fracture morphology, patient habitus, comorbid conditions, concomitant injuries, and surgeon preference.

Aggressive decompression of the neural elements in patients with ASIA type A complete spinal cord injuries has been advocated to optimize the potential for neurological recovery, facilitate reconstruction of the vertebral column, and restore flow of cerebrospinal fluid (CSF) to prevent syringomyelia.

The surgical technique for anterior and posterior instrumentation of the thoracic spine is described in other chapters (see Chapter 294, Chapter 303, and Chapter 304). In the following section we discuss the technique of anterior transthoracic decompression of the thoracic spinal cord. In a later section we discuss selection of treatment options for specific types of thoracic spine fractures.

Anterior Transthoracic Decompression

Anterior transthoracic decompression is used to treat fractures of the thoracic spine that impinge on the anterior canal and spinal cord. We use this approach for patients who are neurologically intact and have an incomplete spinal cord lesion or a fixed kyphotic deformity from previous spinal injury. In the thoracic area, this procedure (when combined with anterior grafting) may be the only treatment rendered, but the decrease in strength of the reconstructed anterior spinal column after anterior strut grafting may require posterior fusion and fixation for adequate stabilization of the spinal column. A concurrent injury to the posterior ligamentous or bony structures, or both, increases the likelihood that posterior stabilization will be necessary. Furthermore, no adequate anterior fixation devices are available for circumferential constructs above T5.

Transthoracic decompression was first described for the treatment of tuberculosis of the spine in 1956 by Hodgson and Stock, who stated that “the region from C.6 to D.4 is reached without undue difficulty” through resection of a third rib.⁸⁸ Hodgson and Stock also advised performing rib resection above the level of the lesion with T4-12 lesions because “it is much easier to work downwards than upwards on the spine” and the rib was available for reconstructive fusion. Although Chou and Selijeskog described transthoracic osteotomy for a variety of lesions,⁸⁹ Eismont and associates credit Paul and colleagues with the first report of using this technique for decompression and fusion of a traumatic injury to the thoracic spine.^36,90 Bohlman and coauthors published the long-term results and details of the surgical techniques.^64,91 In one review of acute injuries to the upper thoracic spine, eight patients were treated by transthoracic decompression and fusion for residual neural compression after spinal column and cord injuries. All eight patients had reached a plateau in their neurological recovery before the anterior decompression. After transthoracic decompression and fusion, five patients achieved independent ambulation, two recovered ambulatory status with assistive devices, and one gained increased motor function without restoration of ambulatory status. In all patients the anterior strut graft fused without instrumentation, but no data were given regarding initial or final angulation at the decompression site.⁹¹

Transthoracic decompression may cause destabilizing effects. Gurr and coworkers demonstrated experimentally that spinal strength is markedly reduced in axial, flexion, or rotational loading after a corpectomy when compared with an intact spine.⁹² The addition of an anterior iliac graft still allowed 3 times the displacement with axial loading, whereas torsional stiffness was less than a third that of an intact spine. Our experience with a variable-length titanium cage has been positive, especially when combined with a rod-screw or screw-plate anterior fixation system (TSLP, AO Synthes, Davos, Switzerland) (Fig. 318-13).

FIGURE 318-13 Lateral intraoperative fluoroscopic radiograph showing a titanium cage packed with salvaged vertebral body and rib that is used to fill a defect in the anterior spinal column after corpectomy for spinal cord decompression, in addition to lateral screw-plate instrumentation.

Surgical Technique

For a lesion in the upper thoracic area, at T10 or above, a double-lumen endotracheal tube allows collapse of the ipsilateral lung to enhance exposure. The spine can be exposed with the patient in either the left or the right lateral decubitus position. The left lateral decubitus position is used most often for the uppermost region of the thoracic spine, whereas the right lateral decubitus position is used for the middle and lower thoracic regions. Either side can be used if necessary to obtain adequate exposure of the lesion.

An axillary roll is placed to prevent stretch palsy of the lower brachial plexus, and the superior portion of the arm is held in a neutral position with an arm support, with the arm being held in forward flexion of no greater than 90 degrees at the shoulder to minimize the risk for upper brachial plexopathy. Wide adhesive tape can be used to secure the position of the patient and should be placed at the level of the greater trochanter and across the shoulder. The tape should be securely affixed to the table. Some surgeons prefer to place a beanbag under the patient, but we are inclined not to do so because not using this device provides additional posterior exposure. This is an advantage in the rare event that simultaneous anterior decompression and posterior stabilization are necessary.⁹³ Care should be taken to prepare an adequate amount of skin: from the midline anteriorly to beyond the midline posteriorly and from just inferior to the axilla down to the iliac crest.

The skin incision is made over the rib one to two vertebral levels superior to the level of the lesion when dealing with lesions from T6 to T10. At the most superior thoracic levels, the skin incision should extend inferior to the tip of the scapula and halfway between the medial border of the scapula and the midline spinous processes (Fig. 318-14A and B). The incision should be extended to the subcutaneous tissues down to the deep fascia and muscles, which are divided in line with the skin incision. The rib to be resected is then stripped subperiosteally and divided with a rib cutter. The inner rib bed is divided to expose the chest cavity.

FIGURE 318-14 Demonstration of anterior transthoracic corpectomy and fusion. A, The patient is placed in the lateral decubitus position with the shoulder extended forward 90 degrees, the elbows straight, and no abduction or adduction. An axillary roll is used as shown. The incision (dotted line) is made over the rib two levels above the vertebral body fracture. B, For exposure above the sixth rib, the posterior extent of the incision is carried cephalad halfway between the medial border of the scapula and the spinous processes. All the intervening muscles are divided and tagged down to the chest wall. C, After entering the thoracic cavity, a self-retaining chest retractor is inserted. The incision is made halfway between the anterior great vessels and the posterior neural foramina, and the segmental intercostal vessels are ligated serially. The vertebra to be excised plus the superior and inferior adjacent bodies are then exposed by extraperiosteal dissection. A malleable retractor is placed on the opposite side of the spine and connected to the chest retractor with a clamp. The malleable retractor protects the great vessels during the corpectomy. A scalpel and rongeurs are used to remove the disks above and below the level of the vertebral fracture. D, An osteotome or chisel is used to excise the vertebral body to the level of the posterior cortex. Each cut with these instruments is made perpendicular to the floor, as long as cancellous bone is encountered. As soon as white cortical bone is encountered, these instruments should no longer be used. E, A high-speed bur can then be used to perforate the posterior cortex into the spinal canal. If the neural compression is significant, a diamond-tipped bur can be used to minimize the chance of dural or neural injury. F, Ninety-degree down-biting Kerrison rongeurs are used to remove bone from the most superficial portion of the vertebral body. G, Reverse-angle curets are used to carefully remove bone projecting into the spinal canal. H, A transverse section of the vertebra shows the extent of the decompression, which is often underestimated intraoperatively. The resection should extend from one pedicle to the other. After completion of decompression, the dura should bulge anteriorly in a uniform fashion both from end plate to end plate and from pedicle to pedicle. If the dura does not bulge out, the surgeon should check for residual neural compression. There is an advantage to leaving more of the anterior vertebral body and associated anterior longitudinal ligaments intact. I, After the corpectomy and diskectomies above and below the level of injury have been performed, a trough is made into the vertebral bodies above and below the corpectomy. If there is any osteoporosis, the trough should be cut through the cancellous bone up to the next intact end plate at the upper end of a cephalad vertebra and the lower end of a caudad vertebra. A ridge of bone should be preserved at the posterior aspect of the adjacent vertebrae to prevent the bone graft from migrating into the spinal canal. J, At the end of decompression and fusion, there should be adequate space between the bone graft and the dura and neural tissue to prevent iatrogenic neural compression. Three rib segments are used as the bone graft in this illustration, but a single large piece of iliac crest can be used and may provide stronger anterior support.

(From Eismont FJ, Garfin SR, Abitol J. Thoracic and upper lumbar spine injuries. In: Browner BD, Jupiter JB, Levine AM, et al, eds. Skeletal Trauma. Vol 1. Philadelphia: WB Saunders; 1993:727-803. Reprinted by permission.)

When exposing the uppermost levels in the thoracic region, care should be taken to not injure the long thoracic nerve, which runs in the midaxillary line from the axilla to the serratus anterior. It is preferable to detach the muscle from the anterior chest wall to avoid cutting the long thoracic nerve. After mobilization of the scapula by dividing the dorsal scapular muscles, rhomboids, and trapezius, the third rib is more easily visualized and a greater area is visualized with the thoracotomy.

Once the ribs have been counted from inside the thoracic cavity and the level of the rib verified, a self-retaining retractor is then inserted over moist laparotomy sponges. With deflation and packing of the lung, the spine can be visually or tactually identified. The bony column is covered with a thin layer of parietal pleura. The proximal portion of the resected rib can be followed to the vertebral column where it inserts into the cephalic portion of the vertebral body of the same level. With such localization, the disk space or spaces can be identified and a spinal needle placed. A cross-table portable radiograph verifies the level.

The parietal pleura is then divided between the rib insertions on the vertebral body and the great vessels until one level superior and one level inferior to the injury levels are exposed. The segmental vessels are then identified in the middle of the vertebral body and are clamped, divided, and tied. Extraperiosteal dissection of the soft tissues overlying the vertebral body can be performed with dissectors or periosteal elevators. The dissection can be carried across the anterior midline of the vertebral body and a malleable retractor placed to protect the great vessels and the esophagus (Fig. 318-14C).

The proximal portion of the rib inserting at the level of decompression has to be removed to expose the pedicle and neural foramen. The disk spaces immediately superior and inferior to the vertebrectomy site should be evacuated with a scalpel and rongeurs. A small periosteal elevator is useful for detaching the cartilaginous end plate, which can aid in disk removal. An osteotome is then used to remove a portion of the vertebral body while taking care to leave the anterior-most portion of the vertebral body attached to the anterior longitudinal ligament, unlike the removal shown in Figure 318-14H. The dura can be exposed by using a power bur, rongeurs, curets, and osteotomes once the dura is identified at the neural foramina by partial resection of the pedicle (Fig. 318-14D-G). The dissection should be extended across the full width of the canal until the pedicle on the distal side is identified. Measurements of vertebral body width from the preoperative imaging studies are valuable. One should explore the superior disk space to verify that any bone fragments attached to the anulus have been removed from the canal. If there is any question of residual bone fragments having penetrated the posterior longitudinal ligament, the ligament must be divided or a window cut made to allow exploration of the epidural space.

The vertebrectomy site should be grafted to reconstruct the spinal column. Iliac crest can be harvested, but we use tibial allograft struts or titanium cages packed with salvaged fragments of the resected vertebral bodies and the resected rib from the thoracotomy site. If a tibial strut is used, the superior and inferior vertebral bodies are notched to lock the graft in place. More recently, a titanium cage (see Fig. 318-12D) packed with salvaged vertebral body and rib has been used to fill the defect in the anterior spinal column. The cage can be expanded to engage the adjacent vertebral bodies and reduce the kyphotic deformity. The space between the strut and the anterior longitudinal ligament is packed with salvaged autologous bone. A rib strut may also be used to fill the defect if there is minimal instability. There should be a space between the strut graft and the dura covering the neural elements; the graft should be locked into the superior and inferior vertebral bodies to prevent posterior migration into the spinal canal (see Fig. 318-14I and J).

Hemostasis should be achieved before closure and after the malleable retractor is removed. An attempt to close the parietal pleura should be made and a chest tube placed. A pleural catheter is also placed in the chest tube or through a separate percutaneous stab wound and is used for the delivery of local anesthetic to assist in postoperative pain control. Pericostal sutures are placed and tied after approximation of the ribs. The overlying tissues are closed in layers. Posterior stabilization and fusion should be performed if necessary to ensure stability of the spinal column. A TLSO brace may be used at the surgeon’s discretion.

Treatment of Specific Injuries

Correct treatment of thoracic spine fractures depends on accurate diagnosis. Accurate diagnosis is dependent on data garnered from the physical and neurological examinations, appropriate diagnostic studies, and proper imaging studies. Table 318-2 lists the specific recommendations of one group for thoracic spine fractures. A more detailed discussion of factors influencing the selection of specific treatment interventions is provided here.

Compression Fractures

Compression fractures are the most common thoracic spine injury (Fig. 318-15A). The mechanism is an axial load, which when applied to the kyphotic thoracic vertebral bodies leads to an anterior flexion vector and a resulting wedge compression deformity of the anterior vertebral body. In the Denis classification, a compression fracture is an isolated anterior column injury that was considered stable because the middle column was spared. These injuries are almost never associated with spinal cord injury. However, it was soon recognized that loss of anterior body height of 50% or greater or a kyphotic deformity of 30 degrees or greater may indicate concomitant posterior ligamentous failure and be associated with an increased risk for long-term deformity.^37,91 The compression fracture morphology persists in TLICS, where direct MRI assessment of the integrity of the posterior ligamentous complex replaces such indirect bony clues to ligamentous incompetence. A history of thoracic laminectomy must be weighed into the interpretation of thoracic compression injuries inasmuch as previous removal of posterior column bony elements may render a seemingly benign compression deformity unstable.

FIGURE 318-15 Four types of thoracic spine fractures as delineated by Denis. A, Sagittal T2-weighted magnetic resonance image depicting T7 compression. Note the high signal within the vertebral body, loss of height of the anterior column, and focal kyphosis at the fracture level. B, Sagittal computed tomographic (CT) reconstruction of a T10 burst fracture. Note the splaying of the spinous processes. These findings are static radiographic signs of a three-column injury and therefore spinal column instability. C, Sagittal CT reconstruction of a Chance fracture, a fracture through the pedicle in the axial plane. D, Fracture-dislocation injury at T10-11 with comminution and displacement of the vertebral bodies.

By definition, a compression fracture has a disrupted anterior and an intact middle column; the posterior column, however, may be intact or disrupted. Treatment of these injuries depends on the status of the posterior ligamentous structures, as well as on the integrity of the bony elements. As discussed earlier, the status of the anterior column can suggest the integrity of the posterior elements: compression of greater than 40% of the anterior vertebral wall or a kyphotic deformity of greater than 25 degrees is often associated with ligamentous incompetency of the posterior elements. If the kyphosis is less than 25 degrees and the anterior body compression is less than 40%, the injury can be treated nonoperatively, either without a brace or in a TLSO with minor restriction of activity.

After 3 to 4 months (with or without an orthosis), lateral upright flexion/extension films should be obtained with the patient out of the brace. If there is no excess motion and no progression of the deformity, the patient can be weaned from the orthosis if in place and start physical therapy to strengthen the muscles atrophied from disuse. The process of weaning may require several weeks. If abnormal motion, progression of the deformity, or continued pain is noted, the patient may be a candidate for surgical stabilization.

When the anterior column is compressed more than 40% or the kyphosis exceeds 25 degrees, surgical management is indicated.^65,66 Consideration should be given to the force of the injury and the age of the patient in borderline cases. An elderly patient with osteoporosis who suffered a low-velocity injury would not necessarily undergo surgery, whereas a young patient involved in a high-velocity injury would be considered for surgery because of the possibility of posterior ligamentous injury.

If there is a possibility of posterior ligamentous disruption with a severe compression fracture, our instrumentation system of choice is a posterior segmental fixation system. This frequently permits reduction of the flexion deformity. Although anterior decompression is not usually necessary with these injuries, destruction of the anterior column from an underlying disorder, such as severe osteoporosis or a high-velocity injury, may necessitate an anterior approach to reconstruct, graft, and possibly fix the anterior spinal column, alone or in combination with a posterior approach.

Complications

The availability of effective spinal instrumentation has allowed the stabilization of most spinal column injuries, but not without risk of complications. Although many intraoperative complications can be avoided with careful planning, tailoring of the surgical approach to the individual patient, and intraoperative monitoring, these procedures are not free of risk. Certain complications—including death, deep venous thrombosis, and pulmonary embolism—are not unique to surgical treatment and are therefore not discussed here.

Neurological deterioration during or after surgery is a very serious complication that accompanies approximately 1% of operations for treatment of a spine injury.^114–116 Overdistraction, inadvertent introduction of instrumentation into the spinal canal, overcompression, or loss of reduction can all lead to neurological deterioration. Overdistraction has been associated with Harrington distraction rod constructs but is less of a concern with posterior segmental fixation systems that do not depend on the competence of ligamentous tissues. Compression can cause herniation of a disk or bone fragment into the spinal canal, with resultant compression of the spinal cord. This injury can be minimized by using this type of construct only when the posterior vertebral body is intact and after anterior decompression and fusion/fixation, ventral decompression and intraoperative somatosensory monitoring, and the use of intraoperative ultrasound. Hooks can compromise the spinal canal, and the close proximity of the spinal cord to the laminae does not leave much space for hooks. The use of pedicle screws, when properly placed, and pedicle and transverse process hooks can reduce but not entirely obviate this complication.

We use intraoperative somatosensory monitoring during all surgical procedures in patients with sufficient neurological function to support the monitoring. Although somatosensory monitoring may not detect local compromise in motor function, we have found it useful. Monitoring of the motor tracts is now possible and is used when available. Removal of instrumentation must be considered if the evoked potentials deteriorate or the patient cannot move muscles distal to the instrumented spinal segments on a wake-up test. The patient must be observed in the postoperative period for neurological deterioration. Loss of reduction, hematoma, spinal cord edema, or disk herniation may develop postoperatively and adversely affect the neurological examination of the patient. The deterioration in neurological function should be evaluated expeditiously with plain films and MRI or with CT and myelography.

Dural lacerations with associated CSF leakage may be the result of the initial injury or a complication of the surgical treatment. Identification of the tear may require removal of additional bone for direct visualization. Primary repair should be attempted, and a dural graft of fascia or allograft should be sutured in place if necessary. Commercial fibrin glue preparations (BioGlue, CyroLife, Kennesaw, GA) are used. A lumbar drain should be considered to reduce intradural fluid pressure and to permit sealing of the dural repair. We no longer subject patients with CSF leaks to postoperative bed rest.

Infections can occur after spinal surgery, especially after a long surgical procedure with complicated instrumentation placement. Superficial infections should be opened and débrided. The wound may be packed open or closed over drainage tubes. Antibiotics should be used. Deep infections should also be treated with aggressive irrigation and débridement. We attempt to keep the instrumentation and bone graft in place. Drainage tubes are left deep to the fascia for 7 to 10 days. If the infection persists, a second procedure can be attempted, but occasionally the infection persists. The instrumentation and graft are normally left in place until the fusion is solid, but the instrumentation may need to be removed later to eradicate the infection.