Compression Fractures

Compression fractures are generally considered stable injuries; they exhibit minimal body height loss (<10%) and kyphosis (<25 degrees) ( Fig. 35A-4 ). By definition, compression fractures do not involve the posterior wall of the vertebral body. Compression fractures most commonly involve the superior and anterior endplate resulting in vertebral body wedging. Other patterns are the anterior body only, the pincer fracture where a fracture line divides the anterior and posterior vertebral body, and less commonly, an inferior endplate fracture. An important component of compression fractures is the maintenance of the posterior osseous ligamentous complex.

Comprehensive classification of type A spinal injuries. The three categories of type A fractures include impaction injuries (A1), of which wedge fractures are most commonly seen; split fractures (A2), of which the pincer fracture is the typical injury; and the burst fracture (A3).

(Redrawn by permission from Gertzbein SD: Classification of thoracic and lumbar fractures. In Gertzbein SD, editor: Fractures of the thoracic and lumbar spine, Baltimore, 1992, Williams & Wilkins.)

Burst Fractures

Burst fractures are characterized by fractures and loss of height of the anterior and posterior portions of the vertebral body. The hallmark of the burst fracture is the retropulsion of the posterior wall and canal compromise. This may lead to neurologic deficits. Centrifugal extrusions of the bone fragments are generally presented. The pedicles are expanded apart, which is best seen as widening of anteroposterior or coronal plane reconstructions. Like compression fractures, several patterns of body and posterior involvement have been described that might affect treatment decisions. Most commonly, the superior endplate is fractured, whereas a more unstable injury is when the fracture comminution extends to involve both superior and inferior endplates.

Magerl and colleagues proposed that burst fractures have an intact PLC. However, the authors of TLICS proposed that some burst fractures can have PLC injury, having an increasing risk of instability. Burst fractures can be associated with laminar and spinous process fractures.

Perhaps the greatest impact the TLICS system can have is in the evaluation and treatment of burst fractures. The TLICS system does not account for some classically described characteristics of burst fractures. Factors such as loss of vertebral body height, segmental kyphosis, and canal compromise, despite their widespread use, have no evidence to support their importance in managing patients without neurologic deficits. Studies have examined the impact of these classic radiographic measures on patient outcome and have shown no relationships with only neurologic function consistently predicting patient outcomes. As an example, kyphosis greater than 30 degrees and/or 50% of vertebral body height loss were indirect radiologic measures of PLC disruption, such as substantial canal compromise. Based on these historical analyses, Radcliff and coworkers studied the relation of loss of vertebral body height, kyphosis, and canal compromise observed on CT scan with the PLC status according to MRI findings. They reported that these factors did not correlate with PLC injury and the MRI should be used when there is clinical concern. However, there is lack of consistent evidence on the utility of MRI in the evaluation and management of spinal fractures. As such, despite the proven utility of the TLICS system, the controversy regarding the treatment of burst fractures remains, especially in the evaluation of the PLC status. Over time, with additional evidence and clinical utilization of the TLICS system, consistency in the treatment of stable burst fractures can be achieved with the betterment of patient treatment and outcomes.

Flexion-Distraction Injuries

Flexion-distraction injuries are a flexion injury of the spine, characterized by a compression injury to the anterior portion of the vertebral body and a transverse fracture through the posterior elements of the vertebra and the posterior portion of the vertebral body ( Fig. 35A-5 ).

Flexion-distraction injury at T11-T12 demonstrates small anterior compression injury but wide posterior splaying consistent with posterior distraction.

The mechanism of injury is rotation about a fulcrum located within the vertebral body, so that the middle and posterior columns fail in tension and the anterior column fails in compression. Its association with extreme forward flexion in automotive accidents results in the literature name of “seatbelt” fractures. The Chance fracture variant occurs when all three columns fail under tension often involving only bony structures ( Fig. 35A-6 ). Various patterns of flexion-distraction and Chance fractures have been described and are differentiated by combinations of bony, soft tissue, and facet articulation involvement.

Denis’ classification of flexion-distraction injuries. These may occur at one level through bone ( A ), at one level through the ligaments and disc ( B ), at two levels, with the middle column injured through bone ( C ), or at two levels with the middle column injured through ligament and disc ( D ).

Many abdominal injuries especially bowel perforation were described in association with flexion-distraction injuries and lead to a high level of suspicion in patients with this injury morphology.

Hyperextension Injuries

Hyperextension injuries can present with anterior column disruption through the disc or the vertebral body, secondary to severe spine hyperextension. These injuries are frequently described in patients with diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) and are considered unstable. They can have or not have PLC involvement, increasing the degree of instability. Sometimes it is possible to see a fracture line crossing the syndesmophytes of the ankylosed spine.

Fracture-Dislocation

Fracture-dislocations are the most severe spinal cord injuries and are commonly associated with neurologic deficits. These injuries have vertebral body displacement, complex fractures, and joint subluxation and rotation, in a multitude of patterns with displacement beyond the normal range ( Fig. 35A-7 ). Compression and burst fractures can be found in association with this complex group of injuries.

Denis’ classification of fracture-dislocation of the spine. A, Type A is a flexion-rotation injury, occurring either through bone or through the disc. There is a complete disruption of all three columns of the spine, usually with the anterior longitudinal ligament remaining the only intact structure. Commonly, this is stripped off the anterior portion of the vertebral body below. These injuries are usually associated with fractures of the superior facet of the more caudal vertebra. B, Type B is a shear injury. The type that produces anterior spondylolisthesis of the more cephalad vertebra usually fractures a facet, but the type that causes a posterior lithiasis of the more cephalad vertebra normally does not cause a fracture of the facet joint. C, Type C is a bilateral facet dislocation. This is a flexion-distraction injury but with disruption of the anterior column in addition to the posterior and middle columns. This disruption through the anterior column may occur through either the anterior intervertebral disc or the anterior vertebral body.

Anatomy of the Thoracolumbar Junction, Spinal Cord, and Cauda Equina

The thoracolumbar junction is typically defined as extending from T10 through L2 (inclusive). This region accounts for more than half of all spinal fractures because it is located at the junction of the mobile lumbar lordosis and the more rigid thoracic kyphosis. Burst fractures make up 10% to 20% of all fractures in this transitional region. The purpose of this chapter is to review pathophysiology, classification, and treatment of thoracolumbar burst fractures.

Unique to this region is also the transition from a spinal cord and the conus medullaris (upper motor neuron) to the cauda equina (lower motor neuron). The conus medullaris usually starts at T11 and ends around the L1 to L2 disc space. When it extends lower into the lumbar spine, it is often associated with a hypertrophic filum terminale and tethering of the spinal cord. In traumatic situations, the level of the injury and its localization with respect to the level of conus medullaris determines the degree of neurologic damage. As an example, a severe burst fracture at T12 might have elements of upper motor cord level injury (bowel and bladder dysfunction) and lower motor neuron pathology (lumbar radicular pain and weakness). The space available for the cord changes from its narrowest region in the midthoracic spine to an increased width in the lumbar region where the composition of the cauda equina made of peripheral nerves are more resilient to injuries.

Burst Fractures in Thoracolumbar Fracture Classifications

In 1943, Watson-Jones first described the comminuted wedge fracture, which would today be called a burst fracture, and highlighted the role of the integrity of the posterior ligamentous complex (PLC) in spinal stability. By the end of that same decade, Nicoll’s classification of thoracolumbar spine trauma further described the morphology of fractures based on a review of injuries sustained by coal miners. It defined stability using an anatomic classification based on four specific structures: the vertebral body; the disc; the intervertebral joints; and most important, the interspinous ligaments (ISLs). It was not until 1970 that Holdsworth. semantically distinguished “wedge compression fractures” from “compression burst fractures,” but in his classifications, both fracture types were stable.

By the 1980s, the term burst fracture was defined in Denis’ classification as one of the four main categories of thoracolumbar injuries. His classification divides the spine into three columns with an emphasis on the middle column, which comprises the posterior vertebral body, posterior disc, and posterior longitudinal ligament. Mechanical instability was defined when two of the three columns were disrupted; therefore, all burst fractures were considered unstable according to this scheme. Denis’ classification also defined neurologic instability when a neurologic deficit occurred in the setting of a spinal fracture.

The evolution in describing burst fractures is highlighted by the difficulty so many authors had in assessing its stability, which ultimately should guide treatment. Therefore, based on 100 computed tomography (CT) examinations of thoracolumbar injuries, McAfee and colleagues further classified them into six categories, including distinct categories for stable and unstable burst fractures. That classification emphasized the role of the PLC (including the facet joints) as a major factor in fracture stability.

McCormack and colleagues have described the load-sharing classification for burst fractures. It is theorized and proven practically that the vertebral bodies’ ability to share load depends on the degree of comminution. In this system, the degree of comminution, fracture fragment displacement, and deformity are each graded 0 to 3 points and summed. Higher scores indicate greater instability and a greater likelihood of failure of short segment fixation. The system has been shown to have good interobserver and intraobserver reliability. In an effort to guide management, the Spine Trauma Study Group developed the Thoracolumbar Injury Classification and Severity Score (TLICS; Table 35B-1 ), which considers burst fractures as an intermediate severity fracture pattern based on radiographic appearance. Surgical recommendations for burst fracture are then guided by both neurologic status and the integrity of the PLC as many classifications have suggested in the past for burst fracture. That classification has demonstrated good intrarater and interrater reliability and validity and will therefore be the basis for the treatment of thoracolumbar fractures in this chapter.

Radiologic Findings of the Burst Fractures

Radiographic findings of a burst fracture on an anterior-posterior (AP) radiograph or coronal CT reconstruction are an increase in the interpedicular distance compared with the level above or below and a decrease in vertebral height. On the lateral radiograph or sagittal CT scan, findings can include a decrease in vertebral height, lack of definition of the contour of the cortices of the vertebral body with retropulsion of the posterior cortex into the spinal canal, local kyphosis around the fractured vertebra, and an increase in the interspinous distance ( Fig. 35B-1, A ). An increase in the interspinous distance should increase the level of suspicion for disruption of the PLC. Comparing this interspinous distance between supine and upright images may identify a functionally incompetent PLC. CT scans are used to further detail the fracture pattern and assess instability (widening of the facet joint) and canal compromise at the level of injury ( Fig. 35B-1, B ).

Lateral ( A ) and anterior-posterior ( B ) plain radiograph views of the lumbar spine showing an L1 burst fracture (small arrow) with retropulsion of bone into the spinal canal (large arrow).

The Posterior Ligamentous Complex

As originally defined by Holdsworth, the PLC is generally defined by five components at the level involved: the supraspinous ligament (SSL) and ISL, the ligamentum flavum (LF), and the right and left facet capsules. Vacarro and colleagues. also added the thoracolumbar fascia as part of the PLC. Determination of PLC integrity, however, remains a topic of controversy despite its central role in management determination.

Physical examination may help in the assessment of the integrity of the PLC. Severity of pain, on palpation of the spinous processes, presence of hematoma, or identification of gaps between them are indicators of disruption of the PLC. Further simple logrolling and assessing pain response can help measure stability of the fracture.

Radiologic imaging has proven helpful but, unfortunately, not definitive in all cases. Vacarro and members for the Spine Trauma Study Group extracted 12 criteria considered important to evaluate PLC disruption on magnetic resonance imaging (MRI) from the published English literature since 1949. Those criteria were posterior edema on short tau inversion recovery (STIR) MRIs; disrupted PLC components (i.e., LF, ISL, or SSL) on MRI; focal kyphosis without vertebral body injury; interspinous spacing greater than that of the level above or below on an AP plain radiograph; palpable interspinous defect on examination; focal posterior tenderness on examination; diastasis of the facet joints on radiograph, MRI, or CT; avulsion fracture off the superior or inferior aspect of contiguous spinous processes; history of the injury mechanism; more than 50% compression of the anterior vertebral body on lateral plain radiographs without fracture of the posterior wall on CT scan; and vertebral translation ( Fig. 35B-2 ). Twenty-eight surgeons returned the survey, and more than half ranked “vertebral body translation” as the most important factor followed by increased interspinous spacing and diastasis of the facet. Although Denis and the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification rely mainly on bony morphology from radiographs and CT scans, the emphasis on the role of the PLC to spinal instability has led to the inclusion of MRI as part of spinal fracture evaluation. MRI was often considered a critical modality to evaluate PLC integrity. In that study, disrupted PLC components (i.e., LF, ISL, or SSL; “black stripe”) on T1-weighted sagittal MRI was the fourth most important factor in evaluating PLC disruption. However, MRI findings should be considered with caution. Vaccaro and colleagues have highlighted low-specificity values for detecting ISL and SSL injuries on MRI, suggesting a large proportion of false-positive injuries on MRI compared to preoperative surgical findings. Thus, despite the central role of PLC integrity in the evaluation and decision making for thoracolumbar spine injuries as suggested by the TLICS, there remain few strict criteria or clear definition in defining a PLC injury, and the exact prognosis associated with PLC injuries related to radiographic, neurologic, and patient-reported outcomes has yet to be defined.

Sagittal ( A ) and axial ( B ) T2-weighted magnetic resonance imaging views of the lumbar spine showing the L1 burst fracture (white arrow) with compression of the spinal cord at the same level with surrounding regions of increased signal intensity corresponding to the surrounding edema (black arrows). The degree of the canal narrowing can readily be seen on the axial image on the right .

Nonoperative Treatment

Indication

In a stable burst fracture (without significant PLC disruption) and absence of a neurologic deficit, nonoperative treatment is the treatment of choice. In a randomized controlled trial (RCT) of 47 consecutive patients with stable burst fractures without neurologic deficit, Wood and colleagues found no major long-term advantage when comparing operative treatment with nonoperative treatment based on radiographic criteria, Short Form 36 (SF-36), and Owestry questionnaires, but more frequent complications and greater cost were found in the operative group. Those findings were not reproduced in a later RCT with 34 patients; Siebenga and colleagues found that for stable burst fracture without neurologic deficit, short segment stabilization provided less kyphotic deformity, better functional outcomes, and higher return to original work than in the nonoperative group. They concluded that in addition to fracture stability and neurologic findings, treatment should also take into consideration the amount of deformity and patient preference with respect to complication risks ( Fig. 35B-3 ).

Lateral and anterior-posterior (AP) plain radiographs of the thoracolumbar spine of a patient with an L1 burst fracture, which was treated nonoperatively with a thoracolumbar orthosis. A, Lateral plain radiograph made with patient in a thoracolumbar orthosis at the time of discharge from the hospital, demonstrating a 22-degree kyphosis. B and C, AP and lateral views, respectively, of the same patient taken 36 months after the injury, demonstrating progression of the deformity to 28 degrees of local kyphosis.

(Figure reproduced with permission from Wood K, Buttermann G, Butterman G, et al: Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit. A prospective, randomized study, J Bone Joint Surg Am 85(5):773–781, 2003.)

Surgical Treatment of Burst Fractures

Surgical Indication

Surgical treatment of thoracolumbar burst fractures is indicated when there is evidence or risk of neurologic worsening or stability compromise. For this reason, the TLICS uses neurologic status and two factors influencing stability (injury morphology and PLC integrity) as components influencing surgical decision. The approach and surgical technique to use should take into consideration three main criteria:

• 1.
  

  The fracture pattern

  
  
• 2.
  

  The ability to decompress neural elements (based on fracture pattern and age of the fracture)

  
  
• 3.
  

  The presence of PLC lesions

Other indications for surgical treatment are when associated with multiple injuries or in those who cannot be managed with an orthosis such as very obese individuals.

Burst fractures can be treated with an anterior, posterior, or combined approach for decompression and instrumentation. Posterior spinal instrumentation at the thoracolumbar junction is well established and has its advantages, including familiarity of the posterior midline approach; the lack of pulmonary, visceral, and vascular structures; and the ability to relatively safely reexplore the surgical site if necessary. In most acute cases, decompression and stabilization can be achieved from a posterior approach with limited associated comorbidities ( Fig. 35B-4 ). Posterior instrumentation also permits stabilization of the posterior elements when the PLC is torn. Limitations of the posterior approach are that the decompression is indirect (usually achieved from reduction of bony fragments by tension of the posterior longitudinal ligament and ligamentotaxis) or, alternatively, by the need to mobilize the dural sac to achieve proper decompression. Further hardware failure and reoperations are common, especially when the vertebral bodies have more severe injury and comminution.

Sagittal ( A ) and axial ( B ) views of the T2-weighted magnetic resonance image of a 51-year-old woman who fell after completing a ski jump and sustained a severe burst fracture of L1 with disruption of both endplates, 20 degrees of local kyphosis, and 65% canal compromise caused by bony retropulsion. She was neurologically intact. Postoperative anterior-posterior ( C ) and lateral ( D ) radiographs show restoration of sagittal alignment with fixation and posterolateral fusion from T11 to L3.

In the past, fusion was routinely performed in conjunction with posterior instrumentation for burst fractures. Fusion-less fracture care has the advantage of minimizing stiffening of spinal segments while still providing stabilizing forces while the fracture heals. This can be performed using an open or minimally invasive technique. In most cases, hardware is removed 9 to 12 months later. Dai and colleagues reported the results of a randomized trial comparing fusion with no fusion after instrumentation for thoracolumbar burst fractures. At 5 to 7 years of follow-up, they found no difference in clinical and radiologic outcomes between the two groups. Tian and colleagues performed a meta-analysis of four studies comparing fusion with no fusion. The fusion-less group had shorter operative times, but no difference in clinical results or complications were present between groups. Radiologic results favored the fusion-less group that had less postoperative vertebral height loss. Complications and hardware failure were not different between groups. The topic is discussed further in Chapter 35E .

Anterior reconstruction with instrumentation can overcome some of the limitations of the posterior approach when direct visual decompression can be achieved, particularly in the case of subacute or chronic fracture in which the bony fragments can only be mobilized with difficulty. Also, the anterior approach allows application of a large distractive force to be applied, restoration of the mechanical integrity of the anterior column, removal of torn or damaged discs, direct decompression of the spinal canal, potential avoidance of iliac crest harvesting, and frequently fusion of fewer levels of the spine.

The combined anterior approach is often indicated for the more severe fractures with neurologic deficits. If a posterior fusion did not result in complete decompression then an anterior decompression should be considered. Similarly, if adequate stability was not achieved after posterior instrumentation and patients are at risk or are developing kyphosis, then anterior reconstruction should be considered. For highly unstable burst fractures treated initially anteriorly, posterior instrumentation should be considered.

In a neurologically intact patient with burst fractures, anterior or posterior approaches have proven to be equivalent for radiographic and patient-reported functional outcomes in a series by Wood and colleagues. Similar results were found in an RCT from Lin and colleagues for burst fractures with neurologic deficit in which radiologic and motor score improvement did not show any significant difference between the two approaches. However, different rates of complications were reported in the two RCTs. Wood and colleagues found that the anterior approach had fewer complications and reoperation; in their series, 17 complications were seen in their posterior group with hardware removal of painful instrumentation in nearly one-third of those patients. To the contrary, Lin and colleagues have suggested that posterior approach would lead to less blood loss, shorter operative times, and better pulmonary function postoperatively.

Currently, there is limited consensus about the effect of timing of surgery on neurologic recovery. Clinical judgment should be taken into consideration, and, in general, spinal care should be handled after the treatment of life- and limb-threatening injuries.

The Anterior Thoracolumbar Approach with Corpectomy and Instrumentation

Surgical Indication, Advantages, and Limitations.

The anterior thoracolumbar retroperitoneal approach is most commonly indicated for burst fractures between T10 and L3, which can also benefit from direct anterior decompression. Other indications include a large retropulsed fragment with marked canal compromise (>50%) and incomplete neurologic deficit and anterior comminution and kyphosis less than 30 degrees requiring additional anterior column support. After a posterior stabilization, an anterior approach should be considered when there is suboptimal neural recovery resulting from inadequate canal ( Fig. 35B-5 ).

Anterior-posterior (AP) ( A ) and lateral ( B ) plain radiographs of a 54-year-old woman who was involved in a roll-over motor vehicle accident with a sustained burst fracture at L1. Axial computed tomography (CT) reconstruction ( C ) shows the appearance of the burst fracture with bone retropulsion resulting in 55% canal occlusion. The bottom row shows the postoperative appearance of the injury: AP ( D ) and lateral ( E ) plain radiographs of the lumbar spine taken 2 years after the surgical stabilization show maintenance of correction. Axial CT reconstruction ( F ) at 2 years after surgery shows only modest 5% residual canal occlusion.

(Reproduced with permission from Wood KB, Bohn D, Mehbod A: Anterior versus posterior treatment of stable thoracolumbar burst fractures without neurologic deficit: a prospective, randomized study, J Spinal Disord Tech 18(suppl):S15–S23, 2005, Fig. 1, A-F.)

The main advantages of the anterior thoracolumbar approach are the possibility to directly visualize the fracture, directly decompress the spinal cord from the side of the pathology, and reconstruct the anterior column. This reconstruction is thought to allow a better correction of the kyphotic deformity than posterior approach. The main limitation of this approach is that it only addresses the ventral or compression side of the spine. Therefore, an additional posterior approach may be required for stabilization in cases in which the PLC and its tension band effect are lost.

For burst fractures of T10 and above, anterior decompression and fusion are performed using a transthoracic approach usually from the right side. A video-assisted transthoracic (VATS) approach may minimize pulmonary injury but is technically demanding and application of instrumentation is challenging.

Surgical Technique: Anterior

Positioning.

For fractures below T12, a left-sided approach with the patient positioned in a right lateral decubitus position is preferred to avoid retraction of the liver and damage to the frail vena cava. Patients are positioned in a lateral decubitus position ( Fig. 35B-6 ). After the patient is positioned, attention is given to check all pressure points, particularly the brachial plexus, under an axillary roll. The elbows and knees are protected with gel pads to protect the ulnar and common peroneal nerves, respectively. The patient might be positioned with the thorax and abdomen leaning slightly forward to allow abdominal contents to fall forward during the exposure. Some surgeons prefer straight lateral positioning to maintain orientation of the vertebral body during the instrumentation. To improve exposure, the fracture level can be placed over the table break and, depending on fracture stability and neurologic involvement, the table can be broken to raise the vertebra of concern into the operative field. At the time of fixation, it is necessary to level the table to avoid the introduction of scoliosis deformity.

A, Positioning of the patient for the anterolateral approach. The arrow points toward the head of the patient. The patient is positioned on the right side, and the left side is exposed and prepared for the approach. This allows the surgeon to avoid damaging the liver during the approach to the spine. Technique of anterior transthoracic corpectomy and fusion. B, The patient is placed in a straight decubitus position with the shoulders extended forward 90 degrees, neutral in terms of abduction and adduction, and with the elbows straight. Care is taken to protect the downside brachial plexus by using a pad just distal to the axilla. The dotted line over the rib represents the incision one level above that of the spinal fracture. C, If the incision is used to expose above the T6 rib, the posterior limb of the incision is extended cephalad halfway between the medial border of the scapula and the spinous processes. All of the intervening muscles down to the chest wall are divided and tagged for later repair. D, After the thoracic cavity has been entered, the self-retaining chest retractor is inserted. The parietal pleura is incised halfway between the anterior great vessels and the posterior neural foramina, and the segmental vessels are ligated at this same level. The vertebra to be excised as well as one vertebra above and one vertebra below are exposed. Extraperiosteal dissection provides the best plane. A malleable retractor is placed on the opposite side of the spine and connected to the self-retaining chest retractor with a clamp. This malleable retractor serves to protect the great vessels during the vertebral corpectomy. E, A scalpel and rongeur are used to remove the discs above and below the level of the vertebral fracture. F, An osteotome, chisel, or gouge is used to excise the vertebral body back to its posterior cortex. Special care is taken to originally position the patient exactly in the straight decubitus position. During the vertebral body resection, using these instruments, each of the cuts is made perpendicular to the floor. These instruments can be used as long as red cancellous bone is encountered. As soon as white cortical bone is encountered, these instruments should no longer be used. G, A high-speed burr can be used to perforate the posterior vertebral body cortex into the spinal canal. When the neural compression is significant, a diamond-tipped burr can be used to minimize the chances of dural or neural injury. H, Down-biting 90-degree Kerrison rongeurs are used to remove the bone on the most superficial portion of the vertebral body. I, Reverse-angle curettes are used to carefully impact the bone from the spinal canal on the far side of the vertebral body. J, The bone resection at the end of the decompression should extend from the pedicle on one side to the pedicle on the opposite side. It is easy to underestimate the extent of bone removal necessary to achieve this. At the end of the neural decompression, the dura should bulge anteriorly in a uniform fashion from the endplate of the vertebra above to the endplate of the vertebra below and from pedicle to pedicle. If the dura does not bulge out concentrically, the surgeon should check for residual neural compression. K, After the corpectomy and resection of the disc above and below the corpectomy. If there is any degree of osteoporosis present, the trough should be cut through the cancellous bone up to the next intact endplate at the superior end of the cephalad vertebra and the inferior aspect of the caudal vertebra. A ridge of bone should be preserved at the posterior aspect of these adjacent vertebrae to prevent migration of the bone graft into the spinal canal. L, At the end of the neural decompression and fusion, there should be adequate space between the bone graft and the dura and neural elements to minimize the chance of producing any iatrogenic neural compression. This illustration shows three strips of rib being used as bone graft, but a single large piece of iliac crest can also be used and may actually provide a stronger anterior strut. A transverse section at the vertebrae above ( M ) and below ( N ) the level of the corpectomy should reveal an adequate posterior rim of cortical bone to prevent migration of the bone graft into the spinal canal and an anterior cortical and cancellous rim of bone to prevent dislodgement of the bone graft.

For lower thoracic injuries, a transthoracic approach is used. Intubation is performed with a double-lumen tube that allows deflation of the right lung during surgery. The patient is positioned in the left lateral decubitus position with the right side up ( Fig. 35B-6, B ). Similar precautions to protect neurovascular structures are carried out as described earlier.

Landmark, Incision, and Approach.

The incision is based on the vertebra affected. Given the cephalocaudal direction of the ribs, the incision should be made on the rib one to two levels above the region of interest. For example, to treat a L1 burst fracture, the incision should be centered on the 11th or 12th rib. The incision follows the ribs on its whole length. After skin incision, the abdominal muscle layers are transected in line with the rib in the following order from posterior to anterior: latissimus dorsi and external oblique; serratus posterior inferior and internal oblique, transversus abdominis, sacrospinalis, and multifidus.

The rib is then dissected subperiosteally, and particular care is given to use an elevator circumferentially, particularly to avoid damage to the subcostal neurovascular bundle. The rib is cut anteriorly at the cartilaginous junction and posteriorly close to the rib head. A self-retaining retractor is then placed. When the 12th rib is excised, its tip is at the junction of the transversalis fascia, pleura, and diaphragm, which facilitates the identification of the retroperitoneal space and dissection of the pleura, which is reflected upward while the quadratus lumborum is retracted downward. Above the 12th rib, the pleural space is accessed through a small incision, which is extended in line with the incision while protecting the underlying structures.

When necessary, the diaphragm is detached from its insertion above the arcuate ligament, leaving 2 cm of the periphery to aid repair at closure. To facilitate closure, it is recommended to leave suture tags of different colors along the diaphragm incision.

In the retroperitoneal space, the peritoneum, retroperitoneal fat, and kidneys are reflected anteriorly to expose the quadratus lumborum and the psoas muscle overlying the vertebral bodies. A malleable retractor can be used to protect and maintain the viscera anteriorly. The psoas is dissected from anterior to posterior of the lateral aspect of the vertebral body until the base of the pedicle is palpated and the ventral neural foramen exposed. In the case of a transthoracic decompression, after the rib is removed, the pleura is opened, and the lateral aspect of the vertebral bodies is exposed. The right lung can then be deflated.

The fractured vertebral body is then localized based on the surrounding hematoma and the deformity and confirmed by an intraoperative radiograph ( Fig. 35B-6, C ). Upon confirmation of the adequate level, the fractured and adjacent levels are exposed by releasing the overlying pleura followed by isolation and ligation of the segmental arteries, which allows the great vessels to be mobilized and facilitates a safe approach to the contralateral side if needed.

Corpectomy and Decompression.

After adequate exposure is completed, discectomies are performed between the vertebra of interest and the adjacent levels ( Fig. 35B-6, D ). The corpectomy can be started using the pedicle as a guide for the posterior margin and the depth of the discectomy for the contralateral border. Using osteotomes or chisels, the middle and anterior vertebral body is resected about 1 cm anterior to the pedicle base ( Fig. 35B-6, E ). The bone from the corpectomy is kept for bone grafting. After an adequate corpectomy is achieved to the contralateral wall and pedicle, decompression of the dural space is performed. The posterior wall is first thinned using a high-speed diamond burr and curettes and Kerrison rongeurs then complete the decompression which should span between the disc spaces and from ipsilateral pedicles to contralateral pedicles ( Figs. 35B-6, F to H ).

Instrumentation and Fixation.

After the corpectomy, the overall alignment is checked and reduction maneuvers applied as needed with manipulation of the spine from external pressure or distraction within the corpectomy site applied with a laminar spreader or using an expandable cage mechanism. Alternatively, the instrumentation can be used as sites for distractors to regain lordosis and vertebral height ( Fig. 35B-7, A and B ). Tricorticate iliac crest, allograft femurs or humeri, titanium mesh cage, and expandable cages are possible options to provide anterior support or fusion. When using cages, vertebral corpectomy bone graft is placed in the cage while structural bone graft from rib resections can be used to bridge both endplates longitudinally. Superior and inferior endplates are prepared using a curette or a burr to promote bleeding and vascular supply to the graft, but attention should be taken not to compromise the mechanical support of the endplates, which can lead to graft impaction and kyphosis. Additional support with internal fixation can be provided with transvertebral screws and rods or plates ( Fig. 35B-7, C to F ). Screws are placed laterally toward the contralateral side with care to not injure the visceral and vascular structure. The endplates and vertebrae posterior walls are used as guides for screw orientation. Precise measurement of the screw length when the opposite cortex is breached with the ball-tip probe is essential. Upon placement of one or two screws in each of the adjacent vertebrae, one or two rods or a plate is placed and gentle compression can be applied to secure the anterior graft or cage in place.

Technique for anterior spinal instrumentation after corpectomy. A, After using a depth gauge directed on the exposed vertebral body, appropriately sized screw lengths are selected to engage the opposite cortex of the vertebral body. The bolts are placed parallel to the adjacent endplate to avoid intrusion into the disc space above and below the corpectomy site. B, Distraction is applied against the bolts, allowing easy insertion of the strut graft into the corpectomy site. C, Determination of proper length of plate via a template is important to avoid impingement of the superior or inferior disc space. Locking nuts are applied and provisionally tightened. D, Compressive forces are applied and locking nuts are tightened firmly. E and F, Finally, two anterior screws are placed, and the nuts are crimped down, preventing possible backing out or loosening.

(Redrawn with permission from Zdeblick TA: Z-Plate-ATL Anterior Fixation System: Surgical Technique. Sofamor Danek Group, Inc. All rights reserved.)

Closure and Postoperative Course.

Before closure, thorough hemostasis is ensured and, if possible, the pleura is repaired over the hardware. A chest tube is placed under direct visualization and the diaphragm os closed following the suture stitches left upon opening. The abdominal musculature is closed in multiple layers.

Postoperative clinical and radiographic monitoring of the chest guide the timing of the removal of the chest tube when there is no evidence of pneumothorax and when drainage has subsided. Postoperative ileus is common and a nasogastric tube is placed as needed.

Postoperatively, a thoracolumbar orthosis may be used up to 12 weeks. Its use is at the surgeon’s discretion depending on the level of instability, bone quality, the addition of posterior fixation, and patient compliance. Standing radiographs of the thoracolumbar spine are taken when the patient is able to stand to ensure construct integrity under physiologic loads. Ambulation is initiated postoperatively as early as possible, but physical therapy typically begins months after surgery when a successful fusion seems likely.

Complications from Anterior Thoracolumbar Approach.

Complications can be grouped into three cate­gories, surgical approach, decompression, and structural integrity.

Early complications related to the approach include pneumothorax, atelectasis, pneumonia, ileus, infection, nerve injury (particularly genitofemoral nerve and nerve root from the lumbar plexus), and visceral and vascular lesions. During decompression, particular care must be taken not to injure the dural sac. If a spinal fluid leak is noted from iatrogenic manipulation or secondary to the trauma, early repair should be attempted. If this fails, cerebrospinal fluid (CSF) drainage via a lumbar drain is recommended. In thoracic cases, the negative pleural pressure keeps CSF leaks from sealing; therefore, lumbar drainage should be considered.

Late complications include incisional hernia. Other late complications are related to disruption of the structural integrity of the construct from bone and bone–instrument failure or pseudarthrosis, which have both been described between 5% and 10%. The frequency of those complications has lessened over the years with the evolution of modern rigid spinal instrumentation, including addition of fixation to the corpectomy graft.

Nonoperative Treatment versus Operative Treatment for Thoracolumbar Fractures without Neurologic Deficit

In the thoracolumbar burst fractures without neurologic deficit, a meta-analysis from Gnanenthiran and colleagues retrieved four major trials for a total of 79 randomized patients (41 with operative treatment and 38 with nonoperative) with a mean follow-up time from 24 to 118 months. No differences in pain, Roland Morris Disability Questionnaires scores, or return to work rates were present between operative and nonoperative groups. At approximately 4 years, the operative group had an improvement in kyphosis from baseline by 1.8 degrees with a mean of 11 degrees, as opposed to a kyphosis of 16 degrees with a worsening of 3.3 degrees in the nonoperative group. Although the amount of correction was significantly different between the treatments, the final degree of kyphosis was not. Operative treatment was also associated with higher complication rates and costs. There was also no association found between kyphosis and pain. Return to work rate were 67% for the nonoperative group compared with 70% in the operative group, a statistically insignificant difference.

Comparison of Anterior and Posterior Approach

Wood and colleagues conducted a prospective randomized study comparing anterior versus posterior treatment of stable thoracolumbar burst fractures without neurologic deficit or loss of structural integrity of the PLC. Thirty-eight patients had a minimum 2-year follow-up, 18 had posterior spine fusion and 20 had an anterior approach. Although lengths of hospital stay and operating times were similar, blood loss was higher in the anterior group, but significantly more adverse events (instrumentation removal, wound dehiscence, instrumentation, or bone failure) were observed in the posterior group. Clinical results between the two groups were similar and demonstrated good pain reduction based on visual analog scale (VAS) scores, improvement in disability score (RMFDS) to 8.3 for posterior group and 8.9 for the anterior group, and ability to return to work after 6 months of 44% for the posterior group and 55% for the anterior group. The study concluded that anterior surgery might lower complications and prevent additional surgeries.

Lin and colleagues also conducted a prospective randomized study comparing anterior versus posterior treatment of thoracolumbar burst fractures but included patients with neurologic deficits and unstable fracture patterns. A total of 64 patients were recruited and equally distributed in comparable group for baseline characteristics. At a minimum of 2-year follow-up, all patients achieved adequate solid fusion and significant neurologic improvement independent from the approach used. In that study, it was found that the posterior approach was associated with less blood loss, complications, shorter operative time, and better postoperative pulmonary function. Although it is often believed that an anterior approach provides a better decompression from direct visualization, this study demonstrated that the posterior approach provided as good a decompression and neurologic improvement while having fewer perioperative complications.

Comparison of Posterior Instrumentation with and without Fusion

Fusion-less fracture care provides opportunity for stabilization and reduction without permanent stiffening of the spine. Dai and colleagues reported results of RCTs at 5 to 7 years of follow-up in 73 patients who had stable-type vertebral burst fractures. Patients were treated by short segment instrumentation with or without fusion. Operating time and blood loss were less in the fusion-less group. Clinical and radiologic results did not differ between groups. No differences in complications were present, although donor site pain was present in two-thirds of the fused patients.

In a meta-analysis of four studies including 220 patients, Tian and colleagues compared fusion to fusion-less instrumentation for thoracolumbar burst fractures. Similar to the results by Dai, no difference at follow-up was present between groups. Operating time and intraoperative blood loss were less in the fusion-less group. No differences were present in rates of hardware failure or surgical complications.

Fracture-Dislocations

Fracture-dislocations of the thoracolumbar spine result from high-energy injuries. Most commonly, the rostral vertebra is translated anteriorly on the caudal vertebra, but it is not unusual to see injury patterns that include retrolisthesis or lateral translation. Although they can be classified by direction of dislocation, this is arbitrary and practically makes little difference in regard to treatment. They are devastating spinal injuries that are frequently accompanied by a complete neurologic deficit. Fracture-dislocations of the spine inherently disrupt all three columns and are thus unstable and treated with surgery.

Flexion-Distraction Injuries

Two definitions of flexion-distraction injuries have been recently proposed and evaluated for reliability.

Definition A: Flexion-distraction injuries involve an axis of rotation anterior to the anterior longitudinal ligament as opposed to flexion-compression injuries that involve an axis of rotation within the vertebral body

Definition B: Flexion-distraction injuries are any injuries in which there is disruption of the posterior ligamentous complex (PLC) but no retropulsion of the vertebral body into the canal (i.e., there can be some vertebral compression as long as it is not associated with retropulsion, which would make it a flexion-compression injury).

In the study survey, 67% of the treating physicians agreed to definition B, and the remaining 33% agreed to definition A. In reality, these are similar injury patterns that both include disruption of the PLC. The more recent classification systems strongly suggest that these unstable injuries require immobilization or an open reduction, instrumentation, and fusion to restore alignment and prevent secondary neurologic injury. Here it is important to understand that the mechanism of injury will frequently guide the surgical planning. These definitions may be inadequate and truncated because these injuries have long been postulated to represent a continuum of a flexion and distraction moment where the PLC fails followed by the disruption of the facets, posterior longitudinal ligament, the disc, anterior longitudinal ligament, and finally displacement of the superior vertebral body on top of the other that often injures the spinal cord or cauda equina. Additionally, other forces can be part of the injury, including rotation, coronal angulation, extension, and compression, with the latter causing concurrent fracturing of the body.

Another pattern similar to flexion-distraction injuries is the eponymous Chance fracture. In this injury, an extreme distraction moment imparted to the thoracolumbar spine results in the fracture line extending from the posterior spinouts process through the pedicles, vertebral body, and anterior longitudinal ligament. The injury usually involves primarily bone, but varying amounts of posterior ligamentous and discoligamentous injury may be present.