Each year, more than 150,000 persons in North America sustain fractures of the vertebral column. Injuries to the thoracolumbar and lumbar spine constitute most of these fractures. The immediate neurologic damage that accompanies the bony destruction results in nearly 5000 cases of paraplegia per year. The mechanisms and severity of injuries reflect a mechanized and risk-taking culture.
Since Mixter and Barr first described an operative procedure for the management of lumbar disk disease, the goals of spinal surgery have been decompression of the neural elements and preservation of normal anatomy and biomechanics. Numerous investigators have attempted to define stability and to recommend treatment based on the presumed injury mechanism.
In the 1930s, Watson Jones considered spinal fractures to be pure flexion fractures and treated them with hyperextension casts. In 1949, Nicoll reported on 166 thoracolumbar fractures in coal miners and classified these injuries as anterior wedge fractures, lateral wedge fractures, fracture dislocations, and neural arch fractures. In 1949, Nicoll attempted to define stable versus unstable fractures using an anatomic classification. In his view, the major determinant of stability was the integrity of the interspinous ligament.
Later, Holdsworth introduced the first modern classification, which was based on the two-column theory of spinal column stability. This classification had a major impact on the understanding of thoracolumbar injuries.
In the 1980s, Denis proposed the three-column theory of spinal instability, which remains widely accepted because of its simplicity and the anatomic description. This proposal was based on the meticulous analysis of 412 thoracolumbar spinal injuries.
In Great Britain, Ludwig Guttman pioneered current concepts of spinal cord rehabilitation in the 1940s. Before this time, the mortality for patients with spinal cord injury was 80-90% within the first year. Most patients developed pressure sores or urinary sepsis that led to death. Guttman obtained reduction of spine fractures using traction and postural reduction, revolutionized nursing techniques, and introduced a comprehensive program of rehabilitation. The dramatic reductions in mortality and morbidity obtained with these methods countered the perception that these cases were hopeless and caused surgical stabilization of the traumatized spine to be considered logical and practical.
Initial attempts at spinal instrumentation used wire and screw fixation for spinal fractures and were first reported in the late 1800s. However, these materials were not suitable for internal fixation. Metals were subject to electrolysis when placed in tissue. In 1930, Vitallium, an alloy of chromium, molybdenum, tungsten, and cobalt, was introduced for internal fixation.
However, significant advances in spinal instrumentation did not occur until after World War II, when Rogers described the interspinous wiring technique. Also in the 1940s, Harrington introduced the distraction rod fixation system, which, although introduced for the treatment of scoliosis, was found to be useful to reduce and stabilize spine fractures. In 1945, Cloward introduced the technique of posterior lumbar interbody fusion. In the 1970s in Mexico, Luque introduced the sublaminar wiring technique, which was combined with the use of rods.
The 1980s produced a proliferation of spinal instrumentation systems. Roy-Camille in France developed modern pedicle screws. Cotrel and Dubousset in France developed a system consisting of rods, multiple hooks, and screws. This system rapidly replaced the Harrington distraction rod and the Luque rod constructs in the treatment of thoracic spine injuries. Since then, multiple systems have become available for instrumental fixation of the spine based on the system introduced by Cotrel and Dubousset.
This article reviews the diagnosis and management of acute lumbar vertebral fractures. (For more information, see Lumbar Compression Fracture and Lumbar Spine Trauma Imaging.)
The lumbar spine consists of a mobile segment of five vertebrae, which are located between the relatively immobile segments of the thoracic and sacral segments. The thoracic spine is stabilized by the attached rib cage and intercostal musculature, whereas the sacral segments are fused, providing a stable articulation with the ilium.
The lumbar vertebrae are particularly large and heavy as compared with the cervical and thoracic vertebrae. The bodies are wider and have shorter and heavier pedicles, and the transverse processes project somewhat more laterally and ventrally than other spinal segments. The laminae are shorter vertically than are the bodies and are bridged by strong ligaments. The spinous processes are broader and stronger than are those in the thoracic and cervical spine.
The intervertebral disks consist of two components, the annulus fibrosus and the nucleus pulposus. The annulus is a dense fibrous ring located at the periphery of the disk that has strong attachments to the vertebrae and serves to confine the nucleus pulposus.
Because the lumbar spine must transmit all of the compressive, bending, and rotational forces generated between the upper and lower body, it is surrounded by powerful musculature and ligaments.
The lumbar spine is a complex three-dimensional structure that is capable of flexion, extension, lateral bending, and rotation. The total range of motion is the result of a summation of the limited movements that occur between the individual vertebrae. Strong muscles and ligaments are crucial in supporting the bony structures and in the initiation and control of movements.
During flexion, the intervertebral disk is compressed anteriorly, and the spinal canal is widened. Some sliding movement of the articular process occurs in the zygapophyseal joint. This movement is limited by the posterior ligamentous complex and the dorsal muscles.
Extension of the lumbar spine is more limited, producing posterior compression of the disk and narrowing of the spinal canal, along with sliding motion of the zygapophyseal joint. The anterior longitudinal ligament, ventral muscles, lamina, and spinous processes limit the extension of the lumbar spine.
Lateral bending involves lateral compression of the intervertebral disk on the concave side and sliding separation of the zygapophyseal joint on the convex side. An overriding of the zygapophyseal joint occurs in the concave side. The intertransverse ligaments limit the lateral bending of the spine.
Rotation of the lumbar spine involves compression of the annulus fibrosus fibers. It is limited by the geometry of the facet joints and the iliolumbar ligaments.
The motion of the lumbar spine cannot be considered without considering the synchronous movements of the cervical and thoracic spine. The entire spinal column moves as a whole in all planes of motion. Each region of the spine has its own characteristic curvature. These curves allow an upright posture while maintaining the center of gravity over the pelvis and lower limbs. Most rotation is accomplished by the cervical spine; flexion and lateral bending are primarily cervical and lumbar functions.
The intervertebral disks are thick and strong. The annulus fibrosus receives most forces transmitted from one vertebral body to another, and it is designed to resist tension and shearing forces. The nucleus pulposus is best designed to resist compression forces. It receives primarily vertical forces from the vertebral bodies and redistributes them in a radial fashion to the horizontal plane. This structure allows the intervertebral disks to dissipate the axial loading.
The forces responsible for spinal fractures are as follows:
The most common acute fractures are compression fractures or vertebral endplate fractures caused by sudden axial loading, transverse process avulsion by the origin of the psoas muscle, spinous process avulsions, and acute fracture of the pars interarticularis from hyperextension.
Vertebral body compression is more common in patients with decreased bone density.[1, 2] In adolescents, it is relatively common to find endplate fractures or apophyseal avulsion fractures. All of these injuries generally are stable and heal with immobilization and nonsurgical management.[3, 4]
Spinous process fractures may occur as a result of direct trauma to the posterior spine or as a result of forcible flexion and rotation. These injuries usually are not associated with neurologic deficits. Violent muscular contraction or direct trauma can cause fractures of the transverse processes. For example, a football helmet blow to the back can cause fractures of either the spinous or transverse process. Despite their relatively innocuous appearance, these fractures can cause significant bleeding into the retroperitoneal space, resulting in acute anemia or ileus.
Acute traumatic spondylolisthesis usually is associated with major trauma and usually is caused by extreme hyperextension. Although patients with a new fracture of the pars interarticularis may have a slip present at the time of the injury, a slip can occur months to years later as the disk degenerates under shear loads that it cannot sustain.[5]
The National Spinal Cord Injury Registry, established by Ducker and Perot, reported that 40% of spinal injuries were caused by motor vehicle accidents,[6, 7] 20% by falls, and 40% by gunshot wounds,[8] sporting accidents,[9] industrial accidents, and agricultural accidents combined. Such injuries can also be the result of child abuse.[10]
The spectrum of injury severity related to motor vehicle accidents ranges from minor soft tissue contusions to paraplegia and death. Numerous variables relating to the type and severity of the crash, the type of vehicle, and the use of safety restraints have an impact on the frequency and severity of the spinal injury.
An analysis of patients admitted to Rancho Los Amigos Spinal Cord Injury Center from 1966 to 1972 showed that gunshot wounds were second only to motor vehicle accidents as a cause of traumatic paraplegia. In a series of patients with spinal injuries in south Florida, gunshot wounds caused 34% of the injuries, and motor vehicle accidents caused only 28%; the remaining injuries were attributable to falls (19%), sports- and water-related injuries (8%), and other causes including industrial accidents (12%). For a study of 49 cases in South Africa, see Le Roux and Dunn.[8]
After autopsies on more than 5000 service members killed in Iraq and Afghanistan, Schoenfeld et al found than 38.5 had sustained at least one spinal injury. This is a higher percentage than was previously thought.[11]
Spinous process fractures may occur as a result of direct trauma to the posterior spine, and violent muscular contraction or direct trauma can cause fractures of the transverse processes.[12] Direct trauma also can cause a fracture of an articular process.
Accidents are the fourth leading cause of death in the United States, after heart disease, cancer, and stroke. Annually, accidents account for about 50 deaths per 100,000 population. Of these deaths, approximately 3% are the direct result of spinal fractures with spinal cord injury from trauma. More than 150,000 persons in North America sustain fractures of the vertebral column each year, and 11,000 of these patients sustain spinal cord injuries.[13]
The thoracolumbar spine and lumbar spine are the most common sites for fractures because of the high mobility of the lumbar spine compared to the more rigid thoracic spine.[14] Injury to the cord or cauda equina occurs in approximately 10-38% of adult thoracolumbar fractures and in as many as 50-60% of fracture dislocations. The rate of bony injury without neurologic consequence is undoubtedly higher. However, statistics are unreliable because of the lack of accurate reporting.[15]
A high percentage of lumbosacral fractures occur in individuals younger than 30 years. Nearly 60% of patients have serious disabling deficits. Each year, approximately 12,000 persons sustain spinal cord injuries secondary to spinal fractures, 4200 of them die before reaching the hospital, nearly 5000 patients develop paraplegia, and an additional 1500 die during the initial hospitalization.
In a study performed among navy aviators, the overall incidence of thoracolumbar fracture was 12.8 cases per 100,000 aviators per year. Helicopter crashes and parachuting accidents accounted for 73% of fractures, and neurologic injury occurred in 10% of aviators.
The international rate of spinal fractures is difficult to determine because of differences in data collection and reporting among countries. In developed countries, traffic accidents seem to be the most common causes of spinal fractures and spinal cord injuries, whereas in less developed countries, the most common causes seem to be falls.
Osteoporosis is a known risk factor for the development of spinal compression fractures.[16, 17] In an analysis of patients with osteoporosis in Oviedo, Spain, the prevalence of vertebral fractures ranged from 17.4% to 24.6%. Fractures were more common in women than in men, and a relatively high frequency of vertebral fractures was seen in men aged 50-65 years.[1, 2, 18] The trabecular bone score (TBS) may prove useful as a complementary tool for assessing fracture risk in the setting of osteoporosis.[19, 20]
In a study of 402 women living in Beijing, China, the prevalence of vertebral fractures was 5% in a group aged 50-59 years and 37% among women aged 80 years or older.[21] See also the Fracture Index WITH Known Bone Mineral Density (BMD) calculator.
The outcome and prognosis of patients with lumbosacral fractures depends on their neurologic condition. Patients with no neurologic deficits or partial deficits generally have a good prognosis, whereas those with complete injuries remain paraplegic. Other factors (eg, age, comorbid conditions, associated injuries, and general medical complications) also have an impact on outcome.
Although little consensus exists regarding the optimal timing of spine fracture fixation following blunt trauma, potential advantages of early fixation (within 72 hours of injury) include earlier patient mobilization and, probably, fewer septic complications related to pneumonia.
Patients who survive their original spinal cord injury have high residual morbidity. Studies of long-term survival among patients who sustain spinal cord injuries revealed that about 80% patients with spinal injuries live 10 or more years after injury, compared with a normal 10-year life expectancy of 97%. Survival rates are much lower for patients with complete lesions than for patients with incomplete cord injuries. For a study of the direct medical costs of spine fractures, see van der Roer et al.[22]
Patients with lumbosacral fractures present with severe pain, deformity, and neurologic deficits related to compression of neural structures.
Fractures of the thoracolumbar junction can produce a mixture of cord and root syndromes caused by lesions of the conus medullaris and lumbar nerve roots. Complete damage of the conus medullaris is manifested as no motor function or sensation below L1. Patients with complete damage to the sacral portion of the cord have loss of control of bowel and bladder function and sacral motor paralysis of the lower extremities with preservation of some movement of the hips and knees and preserved knee jerks and sensation in the lumbar dermatomes.
Lower lumbar fractures may cause solitary or multiple root deficits. However, massive disk herniations, fracture-dislocations, and burst fractures in the lumbar region can cause a cauda equina syndrome with variable paraparesis, asymmetrical saddle anesthesia, radiating pain, and sphincter disturbances.
The physical examination of a patient with an acute lumbosacral fracture usually is limited by severe pain. In the spinal examination, inspect the overlying skin for abrasions or contusions. Pay attention to general deviations from the normal spine curves. Muscle spasm from pain frequently flattens the spine, whereas spinal fractures may cause a kyphotic or scoliotic deformity. In addition, palpate the spine for areas of tenderness or fractured or displaced spinous processes.
Multiple traumatic injuries,[23] spinal shock, or sedation can make the initial neurologic examination difficult. Document any neurologic deficit according to the American Spinal Injury Association (ASIA) Motor Index. In all conscious patients, perform a motor examination. Muscle strength and weakness are graded from a strength of 5/5, considered normal, to a strength of 0/5, considered paralysis, as follows:
The ASIA introduced the ASIA impairment scale, which consists of five degrees of impairment, as follows:
In addition, a detailed neurologic evaluation should include the following:
The cutaneous abdominal reflex, the ocavernosus reflex, the wink, and the presence of the Babinski sign also should be noted and documented. The Beevor sign consists of a cephalic movement of the umbilicus when the patient is asked to elevate his or her head in the supine position. The presence of this sign denotes paralysis of the lower abdominal muscles. Always include a rectal examination to check for rectal tone and voluntary sphincter function.
Repeat the neurologic examination and document the findings at regular intervals to monitor for improvement or deterioration in the patient's neurologic status over time.
Spinal shock can last 24-48 hours, suppressing all reflex activity below the level of the lesion. The return of reflex activity (bulbocavernosus and anal reflexes) in the absence of any return of sensation or motor function generally is a poor prognostic indicator. Some return of motor or sensory function below the level of the lesion indicates the possibility of some return of useful neurologic function.
In 2013, the AOSpine Spinal Cord Injury and Trauma Knowledge Forum developed a simple classification of thoracolumbar spine injuries that included three primary types of fractures and nine subtypes.[24] The three main types are as follows:
Type A injuries are subclassified as follows:
Type B injuries are subclassified as follows:
In addition, the following six neurologic grades are specified and should be considered in a complete assessment:
The evaluation of a patient with an acute lumbar spine fracture should include routine laboratory tests, such as the following:
Spinal fractures often are associated with open fractures of the limbs, with significant blood loss and acute anemia. Additional spinal fractures at noncontiguous levels can occur, often in high-energy injuries.[25] These must be excluded. A careful medical history should be documented, and a careful physical examination, including a thorough neurologic examination, should be performed.
The combination of plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) allows bony and ligamentous injuries to be defined. Analysis of the radiologic studies should be based on biomechanical concepts. The information obtained from these studies allows classification of the injuries and identification of unstable injuries, and it aids in selection of the proper instrumentation to adequately stabilize the bony elements.[26]
The most important initial radiographic examination is a complete spinal radiograph series that includes anteroposterior (AP), lateral, and oblique views. Upright, weightbearing, or flexion and extension radiographs may be useful in determining instability from ligamentous injuries in some cases. (See the image below.)
View Image | A 42-year-old man fell from a tree. He arrived at the hospital with a complete paraplegia. Plain radiographs reveal a fracture of L2 with L2-L3 sublux.... |
Analysis of plain radiographs should proceed in an organized sequence, beginning with the alignment on both AP and lateral radiographs, with identification of the margins of the vertebral bodies, the spinolaminar line, articular facet joints, the interspinous distance, and the position of the transverse processes. Oblique radiographs are useful in examining for pars interarticularis fractures and facet subluxation.
In patients with severe multiple traumatic injuries, the preliminary radiology studies performed in the trauma room are essential for the management of patients with traumatic injury to the spine. They will have an impact on the need for further testing and type of immediate management.
Abnormalities of alignment include disruption of the anterior or posterior vertebral body lines, disruption of the spinolaminar line, dislocated facets, and rotation of spinous processes. Kyphotic angulation often is associated with misalignment and bony fractures. Disruption of the posterior margin of the vertebral body line and widening of the interpediculate distance are important signs of vertebral disruption. Narrowing of a disk space usually accompanies a flexion injury and is seen at the level above the fractured vertebra. Widening of the facet joint or complete baring of the facets indicates a severe posterior ligamentous injury. These findings usually are associated with widening of the interspinous distance.
After the analysis of routine spinal radiographs, CT is performed on areas of suspected bony injury. CT best defines complex fractures and involvement of the posterior elements. The scan should include one full vertebra above and one full vertebra below the level of the fracture, with a thinkness of 3-5 mm. Both bone and soft-tissue windows should be imaged and coronal and sagittal reconstructions obtained. (See the images below.)
View Image | CT scan of a 42-year-old man who fell from a tree. He arrived at the hospital with a complete paraplegia (same patient as in Image above). Note the la.... |
View Image | CT scan showing a burst of the L2 vertebral body. |
Fractures oriented in a horizontal plane, such as Chance fractures and fracture-compression, may not be well visualized with axial CT. Coronal reconstructions facilitate the evaluation of complex spinal fractures. Tridimensional reconstructions can be used to better define the extent of canal compromise and posterior element fractures.[12]
MRI allows better visualization of the spinal cord and ligamentous structures.[27] On T2-weighted images, high signal intensity indicates spinal cord injury and edema. Ligament disruptions can sometimes be demonstrated with MRI. The anterior and posterior longitudinal ligaments are best seen on T1- and T2-weighted images, respectively. Identifying disrupted ligaments frequently is easier than identifying intact ligaments.
One disadvantage of MRI is the need for special nonmagnetic mechanical ventilators and other life-support monitors. Some patients who are hemodynamically unstable may not be candidates for MRI. In addition, patients with multiple traumatic injuries frequently pelvic fractures stabilized with external fixators, which may produce significant metallic artifacts. MRI is contraindicated in patients with implanted pacemakers, dorsal column spinal cord stimulators, vagal nerve stimulators, or other metallic mechanical implants.
Needle electrode muscle evaluation studies and nerve conduction studies are complementary techniques, usually performed together. Because results usually are negative if the studies are performed during the acute period, it is important to perform these studies during the subacute phase (1 or 2 weeks following the injury).
Electromyography (EMG) can show evidence of denervation in the lower-extremity muscles or abnormalities in the sphincter muscles. Examination of the paraspinal muscles makes it possible to distinguish lesions on the spinal cord or cauda equina from lesions in the lumbar or sacral plexus.
Nerve conduction studies are an essential part of the evaluation of suspected radiculopathy. For example, demonstration of a superficial peroneal sensory response in the face of L5 symptoms or a sural sensory response in the face of S1 symptoms is useful in localizing the lesions to proximal levels. Motor nerve conduction study results can be normal in most patients with lumbosacral radiculopathies, and peroneal motor conduction velocity may be mildly slowed.
Patients with spinal fractures can develop urinary retention.
Methods of objectively testing the behavior of the lower urinary tract during filling, storage, and micturition include uroflowmetry, cystometry, sphincteric EMG, and combined studies. The appropriate use of urodynamic testing provides valuable information for the evaluation and subsequent treatment of neurourologic dysfunction.
Somatosensory evoked potentials and nerve action potentials may be employed both to illustrate preoperative dysfunction and to confirm postoperative improvement.
The decision whether to perform surgery in the acute setting is made by the surgeon, depending on the stability of the fracture, the radiologic evidence of spinal cord or cauda equina compression, the patient's neurologic examination, and the overall status of the patient. In general, decompressive surgery is not indicated for patients with complete deficit lasting more than 48 hours and is advocated for patients with partial cord or cauda equina injuries.
The relation between the timing of surgical decompression and the neurologic outcome has been widely debated. Some evidence in the literature suggests that acute surgical therapy decreases the length of hospitalization and related costs, facilitating rehabilitation in many patients with spine injury.
Numerous factors must be considered in the selection of the surgical approach, including the degree of bone destruction, associated ligamentous injury, presence and degree of neurologic deficit, age and medical condition of the patient, and other associated injuries.
With regard to potential future therapeutic developments, the use of growth factors for the induction of spinal fusions is an attractive approach. Some studies have shown that viral vectors can be used to implant osteoinductive growth factor genes directly into the paraspinal muscles or into cells that can be subsequently implanted next to the spine. These osteoinductive factors enhance the activation and differentiation of pluripotent stem cells to produce mature bone.
Numerous studies support the view that morphogenic bone proteins (ie, bone morphogenetic protein type 2 [BMP-2] and other polypeptides, such as transforming growth factor beta), acidic and basic fibroblast growth factors, insulinlike growth factors, and platelet-derived growth factors are effective in promoting bone formation and fusion. Studies using BMP-2 have demonstrated the same rate of fusion reported in studies using autologous iliac crest bone graft, avoiding the morbidity of harvesting iliac crest bone.[2] However, the high cost of this therapy limits its widespread use.
Studies are being performed on a variety of proteins with a range of physiologic activities in the growth and development of numerous organ systems, including the heart, liver, skeleton, tendons, ligaments, and skin. Their use in humans is currently under investigation.
Initial management of lumbar spine injury begins in the field. Any patient in whom a spinal injury is suspected should be placed on a board in a neutral supine position and immobilized in a neck collar for expeditious transportation to a trauma center.[28]
In the emergency department, all patients should be treated as though they have a spinal injury until spinal injury can be ruled out. The Advanced Trauma Life Support (ATLS) guidelines of the American College of Surgeons should be followed. Stabilization of the patient's airway and hemodynamic status should precede any treatment in order to secure an adequate oxygenation and tissue perfusion. A Foley catheter should be inserted. In patients with neurologic deficit, immediate peritoneal lavage often is advocated to rule out intra-abdominal injuries.[29, 30]
Once the patient has been resuscitated, plain films of the cervical, thoracic, and lumbosacral spine should be obtained.
When possible, a detailed history should be obtained to ascertain the mechanism of injury and the relative force sustained.
Individuals who sustain falls often have hyperflexion injuries at the thoracolumbar region in association with pelvic and lower-extremity fractures.
Persons who wore seat belts during motor vehicle accidents often have distraction injuries or associated cervical spine injuries. In these patients, the vertebrae frequently are compressed or dislocated in the horizontal plane. Crawford et al[31] studied the surgical management of pediatric patients with seat-belt fracture-dislocations of the spine.
Head injuries and extremity fractures commonly accompany vertebral fractures. Abdominal or urologic trauma can occur with lumbar fractures, particularly with motor vehicle–type injuries.[7, 32] The possible presence of concurrent direct injuries to adjacent intracavitary soft-tissue structures (eg, renal, spleen, or liver lacerations) must be considered.
In general, the more caudal the vertebral injury, the greater the biomechanical forces sustained and the greater the propensity for injuries to the pelvis and sacrum.
As early as possible and within 8 hours following injury, all patients with spinal cord injuries should receive intravenous (IV) methylprednisolone at 30 mg/kg in a bolus, followed by infusion at a rate of 5.4 mg/kg/hr for 23 hours. The results of a prospective trial demonstrated significantly better motor function and sensation at 6 months and 1 year in patients treated with this regimen compared with those given placebo.
The major goal of treatment in patients with disruption of the vertebral column who are neurologically intact is the prevention of neurologic deterioration. If a fracture is stable without nerve compression, surgical treatment may not be required. When a fracture is unstable or when neural compression is present, a decompressive procedure with a fusion, usually with instrumentation, becomes necessary. Stabilization is aimed at minimizing pain and subsequent spinal deformity.
Compression fractures have a disrupted anterior and intact middle column. Treatment of these injuries depends on the status of the posterior ligamentous structures, as well as on the integrity of the bony elements. Compression of more than 40% of the anterior vertebral wall or a kyphotic deformity of more than 25° is often associated with posterior ligamentous injury. If the kyphotic angulation is less than 25° and the anterior body compression is less than 40% of the vertebral height, the injury can be treated nonoperatively.
The patient is placed in a thoracolumbar orthosis (TLSO) with restriction of activities.[33] After 3-4 months in the orthosis, flexion extension radiographs should be obtained.
If no motion is present and the deformity has not progressed, the patient can be weaned from the TLSO over several weeks and can start physical therapy for muscle strengthening. If abnormal motion is present, the deformity has progressed, or severe pain persists, surgical stabilization may be required. If the anterior column is compressed more than 40% or the kyphosis exceeds 25°, surgical stabilization is indicated.
In burst fractures, both the anterior and the middle column are disrupted[34, 35] ; the posterior column may or may not be affected. In burst fractures, it is important to analyze the percentage of canal compromise, the degree of angulation, and the neurologic status of the patient.[36] If the canal compromise is less than 40%, the patient may require a TLSO brace worn for at least 3 months. Standing lateral radiographs should be obtained on a regular basis to document any interval increase in spinal deformity.
If the canal compromise is more than 40%, the kyphotic deformity is more than 25°, or the patient develops neurologic changes (eg, changes in motor function or bladder control, new sensory deficits), surgical intervention may be required. Burst fractures can be reduced and stabilized from an anterior or a posterior approach.[37, 38] In patients with burst fractures and significant posterior column disruption, anterior and posterior fusion (360°) is indicated.[39, 40]
In patients with fracture-dislocation injuries, all three columns of the spine are disrupted. This type of injury carries a high incidence of spinal cord injury. In general, most fracture-dislocation injuries require surgical treatment. If a patient with a fracture-dislocation has normal neurologic examination findings, the spine must be stabilized to prevent a spinal cord, cauda equina, or nerve root injury.
When the patient has an incomplete spinal cord injury from a fracture-dislocation, the spinal canal should be decompressed and the spine stabilized to prevent neurologic deterioration. Stabilization of the spine in patients with a complete neurologic deficit from a fracture-dislocation may prevent progressive kyphotic deformation, allowing early mobilization and rehabilitation, thereby minimizing the hospital length of stay.
Surgical intervention is often necessary for patients with unstable fractures or those with neurologic deficits related to compression of the neural structures by bony elements or hematomas, partial cord injuries, or cauda equina injuries. In patients with fractures and associated spinal cord injury, the efficacy of decompressive surgery varies according on the level and degree of injury.[41, 42]
In general, if a patient has a complete neurologic deficit (paraplegia or tetraplegia) and the neurologic examination findings do not improve within 48 hours, decompressive surgery is not indicated, because it will not produce an improvement in neurologic function.
Patients with cauda equina or incomplete cord lesions, however, have been shown to benefit from decompressive surgery even after long delays. Some studies have failed to demonstrate a correlation between the degree of canal compromise at the thoracolumbar junction and neurologic deficits. In contrast with patients with spinal cord injuries at the cervical and thoracic spine, patients with nerve root compression at the lumbosacral region often achieve better outcomes following surgical decompression.
The effect of the timing of decompressive surgery on the rate of neurologic recovery also has remained unclear.[43, 44] Improved neurologic function has been reported with early and late decompression. Most studies have reported on the neurologic recovery associated with late anterior decompression and have not directly analyzed the significance of the timing of surgery. Several studies showed that early spine fixation (≤48 hours) reduced morbidity and resource utilization.[45]
There appears to be a trend toward early surgical intervention in patients with spinal instability or neurologic deficits resulting from compression of the neural structures.
Various operative techniques are used in the treatment of spinal trauma. The surgical approach used is determined by the following factors:
Modern surgical techniques allow effective decompression of the neural structures via microsurgical approaches. In patients with unstable fractures, the use of segmental instrumental fixation is often necessary in conjunction with a fusion of the spine, via either an anterior or posterior surgical approach. This allows reduction and stabilization of the injured segments.
Regardless of the type of instrumentation and surgical approach, a fusion in conjunction with the segmental fixation is of paramount importance because any type of instrumentation will fail if the spine is not supported by a solid bony fusion.
Surgery is contraindicated in moribund patients in very poor medical condition.
Clinical practice guidelines regarding the management of burst fractures were published by the Congress of Neurological Surgeons in 2018 (see Guidelines).[46]
The surgical procedure usually is performed with the patient under general anesthesia in a prone, lateral, or knee-elbow position. Once general anesthesia has been induced and the endotracheal tube secured, the patient's eyes should be well lubricated and taped shut. For a posterior approach, the author's preference is to perform the procedure with the patient under general anesthesia in the prone position over gel rolls that extend from the shoulders to the lower pelvis; alternatively, a Wilson frame may be used.
The use of a radiolucent Wilson frame on a Jackson table is recommended because it maintains the spine in lordosis and avoids increased intra-abdominal pressure. Increase in intra-abdominal pressure increases venous pressure to the epidural veins, resulting in increased epidural bleeding.
The use of intraoperative spinal cord monitoring of the somatosensory evoked potential (SSEP) and electromyography (EMG) is recommended to minimize the risk of further neurologic deficits.
The authors prefer the use of the operative microscope, which allows increased illumination and visibility.
The preferred posterior skin incision is a midline one. The length of the incision should permit complete visualization of the entire hemilamina rostral and caudad to the appropriate interlaminar space or spaces, as well as the entire facet complex.
The lumbodorsal fascia is incised with the electric knife just lateral to the spinous process and supraspinous ligament. Atraumatic dissection of the muscles off the spinous processes, laminae, and transverse processes is accomplished with a periosteal elevator and electric knife. After exposure of the appropriate interlaminar area, a self-retaining retractor is used to retract the musculofascial layers. Posterior element fractures usually are visualized at this time.
If compression of neural structures has been determined preoperatively, adequate bilateral exposure and decompression of ligaments and bone are then performed with a high-speed drill, rongeurs, and Kerrison punches and carried both rostrad and caudad well beyond the area of neurocompressive pathology. All residual ligamentum flavum is gently microdissected from the dura and nerve root sheath and excised with either a 2- or 3-mm thin-footplate Kerrison rongeur.
Once adequate dorsolateral decompression and exposure of the dural sac and involved nerve root have been accomplished, a generous foraminotomy is accomplished with the thin-plate Kerrison rongeur.
The spine is exposed through a posterior midline incision and subperiosteal muscle dissection. The incision length must be sufficient to enable full exposure of the transverse processes. The dissection is carried out laterally over the facet joint to expose the transverse processes completely at the levels to be fused. All soft tissue is meticulously removed from the grafting area, including the transverse process, the lateral aspect of the superior facet joints, and the pars interarticularis.
The bone graft can be harvested either through the previously made midline incision or through the separately placed lateral incision. The superior and outer margins of the iliac crest are exposed subperiosteally. Multiple corticocancellous strips are harvested.
After adequate bone harvest, the donor bed is copiously irrigated with antibiotic solution and waxed to reduce blood loss. This wound is closed in layers. Decortication of the graft bed usually is performed with a high-speed drill. The harvested bone then is placed onto the recipient bone bed and packed into the facet joints. The wound is copiously irrigated and closed with an absorbable suture.
The intertransverse process region provides ample surface area for graft contact, which results in a high rate of fusion. Exposure of this region requires substantial paraspinal muscle dissection, which can be bloody and time-consuming. This technique does not decrease immediate motion, correct deformity, or maintain spinal alignment and generally is used in conjunction with pedicle screw placement.
Lumbar interbody fusion remains a popular method of arthrodesis because it allows access to the anterior weightbearing spinal column through a standard posterior laminectomy.[47] This technique seems most ideally suited for cases of mechanical instability that require concomitant spinal canal or disk space entry for decompression. Patient position and initial spinal exposure are similar to those described for intertransverse process fusion. The dissection need only be carried out to the lateral aspect of the facet joints.
A standard bilateral laminectomy or bilateral hemilaminectomies are performed. Removal of the medial two thirds of the facet joints adequately exposes the disk space for graft placement. Epidural veins are cauterized and divided. A wide opening is made into the annulus, and the disk is removed. Sharp osteotomes and ring curets are used to remove the cartilaginous endplates. Bone grafts or implants filled with bone graft are impacted into the disk space and levered medially until 60-80% of the central disk space volume has been filled.
The use of this technique in the paramedial space is known as posterior lateral interbody fusion, whereas a more lateral approach is known as transpedicular interbody fusion.[48, 49]
A study by Baumann et al found that demineralized bone matrix was an acceptable alternative to autologous bone graft in posterolateral fusion performed to treat acute traumatic vertebral body fractures of the thoracolumbar spine.[50]
Various approaches to the anterior lumbar and lumbosacral spine have been described. Proper exposure of the anterior lumbar spine requires a detailed knowledge of the neurovascular soft tissue surrounding the anterior spine.
After incision of the abdominal wall musculature, the peritoneal sac is bluntly freed from its attachment to the transversalis fascia until the spine and psoas muscle are identified. The ureter usually remains attached to the posterior peritoneum and is elevated away from the spine during the dissection. It must be identified and protected before any sharp dissection is performed.
The aorta overlies the anterior aspect of the spine and bifurcates into common iliac arteries at about the L4-5 disk space. The inferior vena cava is dorsolateral to the aorta on the right side, and the left common iliac vein crosses the midline behind the iliac arteries and may partially overlie the L5-S1 disk space. Segmental arteries and veins run transversely at the midvertebral body level to enter the aorta and vena cava, respectively. These vessels must be suture-ligated to permit reflection of the great vessels for exposure of the spine.
The lumbar sympathetic chain descends just medial to the psoas muscle and can be identified easily.
Once adequate exposure has been achieved, self-retaining retractors are used. Injury to the great vessels is a common complication of surgery. Therefore, these vessels must be adequately protected during this dissection.
Localization of the vertebral fracture is performed with a cross-table lateral radiograph. Once the correct level has been exposed, the superior and inferior disks are removed by using a long knife, rongeurs, curets, and osteotomes. The vertebral corpectomy is performed by using a high-speed drill, curettes, osteotomes, and rongeurs, with special care taken in approaching the spinal canal.
Once adequate decompression has been achieved, the cartilaginous endplates are removed down to bleeding subchondral bone. Spinal fixation is placed in the adjacent vertebral bodies, and gentle distraction of the corpectomy is achieved with a distractor.
Various donor bone sources are available. The authors prefer to use humerus, femur, or a tibial strut allograft. This can be combined with local autogenous bone from the corpectomy. Autogenous anterior iliac crest bone graft can also be used (see the image below).
View Image | A 37-year-old man who underwent an anterior approach for an unstable L1 burst fracture. A corpectomy was performed, with a vertebral reconstruction wi.... |
The bone graft is carefully shaped to maximize bone contact area and is impacted into the space provided by the corpectomy. The distraction then is removed, further securing the bone graft. A titanium plate or rods are placed on the bolts, securing the graft in position. The retractors are removed, and the wound is then closed in layers.[47]
Reported fusion rates and clinical success with anterior interbody techniques are widely variable. Differences probably are related to surgical technique, the source of donor bone, patient selection, and the method by which determination of fusion was evaluated. Internal fixation and direct current electrical stimulation probably enhance fusion rates.[51]
In a study that included 89 patients who underwent operative intervention for traumatic lumbar burst fractures, Pham et al found a posterior-only approach to transpedicular corpectomy and instrumented fusion to be a viable treatment option that allowed reconstruction of the anterior column while avoiding many of the risks and complications associated with an anterior or a combined anterior-posterior approach.[52]
Internal fixation as an adjunct to spinal fusion has become increasingly popular. Titanium rods are longitudinally anchored to the spine by hooks or transpedicular screws. Powerful forces can be applied to the spine through these implants to correct deformity.
Implants provide immediate rigid spinal immobilization, which allows early patient mobilization and affords a more optimal environment for bone graft incorporation. Numerous clinical and experimental studies demonstrate higher fusion rates in patients with rigid internal fixation than in controls without instrumentation. (See the image below.)
View Image | Postoperative lateral radiograph; although the patient was paraplegic, in order to prevent severe kyphotic deformity of the spine and to allow a rapid.... |
Although various implants are available, pedicle fixation systems are the most commonly used implant type in the lumbosacral spine. The large size of the lumbar pedicles minimizes the number of instrumented motion segments required to achieve adequate stabilization. The technique of pedicle fixation requires a thorough knowledge of the pedicle anatomy.[53]
Several techniques are available for screw placement, but the authors prefer an entry point into the pedicle at the intersection of the middle of the transverse process, the facet joint, and the pars.[54] Once a screw trajectory has been achieved within a pedicle finder, palpation of the cortical margins of the screw tract with a ball tip finder minimizes the penetration of the screw into the spinal canal. A tap is then used to create the threads for the screws.
Finally, the screws can be placed under continuous fluoroscopic guidance. A depth of 50-75% of the anteroposterior (AP) vertebral body diameter is usually recommended for lumbar fixation, while bicortical screw purchase is recommended for sacral fixation. The position of the screws is then assessed electrophysiologically with a nerve stimulator and radiologically with an AP, lateral, and two-dimensional scan of the spine performed with an isocentric C-arm.
Fenestrated pedicle screws may be augmented by the use of polymethylmethacrylate (PMMA) cement in patietns with osteoporotic thoracolumbar fractures.[55]
Compression fractures with an intact posterior cortical wall can be treated by means of a kyphoplasty, ,which involves transpedicular placement of a balloon through a bone biopsy needle and cannula into the compressed vertebral body under fluoroscopic guidance. The balloon is inflated under controlled pressure, resulting in expansion of the vertebral body and creation of a cavity. The cavity is then filled with bone cement. This results in elevation of the endplate and stabilization of the fracture fragments, with a consequent reduction of pain.[56, 57, 58] (See the images below.)
View Image | Patients with compression fractures not compromising the spinal canal can be treated by means of kyphoplasty. Use of a percutaneous balloon allows for.... |
View Image | Patients with an acute compression fracture treated with kyphoplasty. AP and lateral views demonstrate a good expansion of the compressed vertebral bo.... |
View Image | A 47-year-old man was involved in a motor vehicle accident. He arrived at the hospital with paraplegia but preserved sensation in both lower extremiti.... |
A posterior cortical defect in a burst fracture is considered a contraindication for kyphoplasty.
For a comparison of vertebroplasty and kyphoplasty, see Hiwatashi et al[59] and Karlsson et al.[60]
Significant postoperative discomfort limits activity for several days in most patients. A morphine patient-controlled analgesia pump usually is employed during the first 36-48 hours. A molded lumbar or thoracolumbar orthosis is often worn for 3 months.
One study evaluated the effects of two different doses of perioperative pregabalin administration in patients undergoing spinal fusion surgery.[61] The study found that pregabalin 150 mg, but not 75 mg, administered prior to and 12 hours after surgery significantly reduced the use of postoperative opioid consumption for 48 hours without significant side effects.
During the postoperative period, patients with fractures that have resulted in neurologic deficits are prone to multiple complications, including skin decubitus, pulmonary problems, and urinary sepsis (see below).
Nursing care should include frequent repositioning, vigorous pulmonary toilet, and deep venous thrombosis (DVT) prophylaxis.
Intermittent pneumatic compression stockings are indicated for all patients with spinal injuries. If the patient is neurologically intact, pulsatile stockings alone suffice. However, if the patient has neurologic compromise, pulsatile stockings and low-dose subcutaneous heparin are used in combination to prevent DVT. If the patient is immobilized from multiple injuries, heparin should be started after postoperative day 2, even if he or she is neurologically intact.
Intermittent catheterization should be performed in patients with spinal cord injuries and urinary retention. A bowel regimen consisting of stool softeners and suppositories always should be instituted in these patients.
Patients with spinal cord injuries are prone to multiple complications, including decubitus ulcers, pulmonary problems, urinary sepsis, and new fractures.[62] Occasionally, patients develop delayed progressive neurologic deterioration months to years after sustaining spinal trauma as a result of instability and progressive spinal deformation.
Neurologic deterioration can occur from neural traction, compression, or interruption of the vascular supply to the neural elements. The overall risk of neurologic injury from posterior instrumentation is 1-3%. In addition, postoperative neurologic deterioration may occur from graft dislodgment, displacement of the hardware, or hematomas.
Intraoperative injury to major vessels and viscera may occur during vertebral exposure and reconstruction. Dural tears, which may be the result of bone fragments or may occur during the surgical approach, can result in cerebrospinal fluid (CSF) leaks.
Pseudarthrosis is a cause of chronic pain as result of the malunion of the fusion. It may lead to progressive deformity, neural compromise, and pain. Failure of the instrumentation, such as dislodgment or breakage, is usually related to pseudarthrosis.
Infections can occur after spine surgery, especially after a long surgical procedure for a complicated instrumentation placement. Superficial infections should be opened and debrided. The wound may be packed open or closed using retention sutures. Appropriate antibiotics should be employed, starting with coverage against gram-positive cocci and adjusting in accordance with culture results. All attempts should be made to keep the instrumentation and graft in place until the fusion is solid.
DVT is a significant potential complication in patients with spinal fractures. Thromboembolism has been reported to occur in as many as 70% of patients with complete motor paralysis. Pulmonary embolism (PE) significantly affects the probability of survival after a spinal fracture. Mortality figures for patients with PE have not decreased significantly in the last 30 years, emphasizing the need for more effective preventive measures.
Recommendations for prophylaxis are varied and usually include subcutaneous or low-molecular-weight heparin (LMWH), sequential compression stockings, and elastic hose placed on the lower extremities. Patients who develop DVT should be treated aggressively with anticoagulation. If the risk for systemic anticoagulation is prohibitive, thrombectomy or placement of a vena caval filter is an option.
The stress resulting from a traumatic injury, a complicated surgery, and mechanical ventilation can predispose a patient to gastric ulcers. However, the widespread use of prophylactic agents, such as H2-receptor blockers, sucralfate, and proton pump inhibitors (PPIs), has reduced the incidence of severe bleeding from stress ulcers.
Ogilvie syndrome, also known as pseudo-obstruction of the colon, is characterized by massive abdominal distention with a cecal diameter of more than 9 cm. Nausea, vomiting, diarrhea, and severe abdominal distention are common symptoms.
Preventive measures for both Ogilvie syndrome and adynamic ileus include minimizing bed rest, returning to ambulation as early as possible, and limiting the use of narcotics. Early recognition and treatment of these conditions are essential to reduce morbidity and mortality. Initial treatment includes cessation of oral intake, nasogastric suction, insertion of rectal tubes, and cessation of narcotics.
Urinary complications continue to be significant sources of morbidity after spinal injuries. In patients with spinal cord injuries, distention of the bladder can lead to autonomic dysreflexia, impairment of bladder sensation, detrusor hyperreflexia, and sphincter dyssynergia, which can lead to renal damage from hydronephrosis or vesicourethral reflux. These complications are decreased with indwelling Foley catheters. In patients with spinal cord injury, the most frequent source of morbidity is sepsis related to urinary tract infections.
The fusion is evaluated by means of plain radiography, including flexion and extension views, at 6 weeks, 3 months, and 6 months postoperatively. If there is any doubt, computed tomography (CT) is performed.
In October 2018, the Congress of Neurological Surgeons (CNS), with the Section on Disorders of the Spine and Peripheral Nerves in collaboration with the Section on Neurotrauma and Critical Care, issued clinical practice guidelines regarding (1) the role of fusion in instrumented fixation in the treatment of patients with thoracolumbar burst fractures and (2) the role of percutaneous instrumentation in the treatment of these patients.[46] Recommendations were as follows:
A 37-year-old man who underwent an anterior approach for an unstable L1 burst fracture. A corpectomy was performed, with a vertebral reconstruction with Harms cages and a screw to stabilize the cage. The patient subsequently underwent a posterior arthrodesis with iliac crest bone graft and transpedicular screw placement.
A 47-year-old man was involved in a motor vehicle accident. He arrived at the hospital with paraplegia but preserved sensation in both lower extremities. He was immediately taken to surgery for an open reduction of the fracture, decompression of the cauda equina, and arthrodesis of the spine. He regained motor function following the surgery.
A 37-year-old man who underwent an anterior approach for an unstable L1 burst fracture. A corpectomy was performed, with a vertebral reconstruction with Harms cages and a screw to stabilize the cage. The patient subsequently underwent a posterior arthrodesis with iliac crest bone graft and transpedicular screw placement.
A 47-year-old man was involved in a motor vehicle accident. He arrived at the hospital with paraplegia but preserved sensation in both lower extremities. He was immediately taken to surgery for an open reduction of the fracture, decompression of the cauda equina, and arthrodesis of the spine. He regained motor function following the surgery.