You are in: eMedicine Specialties > Orthopedic Surgery > SPINE Lumbar Spine Fractures and DislocationsArticle Last Updated: Jul 19, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Federico C Vinas, MD, Consulting Neurosurgeon, Department of Neurological Surgery, Halifax Medical Center Federico C Vinas is a member of the following medical societies: American Association of Neurological Surgeons, American College of Surgeons, American Medical Association, Congress of Neurological Surgeons, Florida Medical Association, and North American Spine Society Editors: Lee H Riley III, MD, Chief, Division of Orthopedic Spine Surgery, Assistant Professor, Departments of Orthopedic Surgery and Neurosurgery, Johns Hopkins University; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; William O Shaffer, BS, MD, Professor, Vice-Chairman and Residency Program Director, Department of Orthopedic Surgery, University of Kentucky at Lexington; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Mary Ann E Keenan, MD, Professor, Vice Chair for Graduate Medical Education, Department of Orthopedic Surgery, University of Pennsylvania School of Medicine; Chief of Neuro-Orthopedics Program, Department of Orthopedic Surgery, Hospital of the University of Pennsylvania Author and Editor Disclosure Synonyms and related keywords: spinal fractures, acute spinal injuries, lumbar vertebral fractures, thoracolumbar injuries, lumbar injuries, paraplegia, tetraplegia, spinal cord injury, broken back INTRODUCTIONSection 2 of 12
  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. This article reviews the diagnosis and management of acute lumbar vertebral fractures. History of the ProcedureThe Egyptians were the first to describe the diagnosis and to recommend a treatment for the spine and spinal injuries (2500 BCE to 1900 BCE). Hippocrates (400 BCE) described the clinical consequences of a thoracic fracture and recommended a method of reducing the gibbus often associated with these injuries. He designed a racklike traction device (scamnum) to reduce the bony abnormalities of thoracolumbar spine fractures. The patient was extended in the prone position with leather straps at the hips and shoulders while a reducing force was manually placed over the site of the kyphosis. This device was introduced as an alternative to "succussion," which consisted of tying the patient upside down to a ladderlike device that was suddenly dropped, extending the patient's spine in an attempt to reduce the spinal deformity. In the seventh century, Paulus of Aegina employed an external fixation device made of thin sheets of wood to secure the reduction. Paulus of Aegina was the first clinician to suggest that laminar fragments pressing on the spinal cord were a source of pain; he advocated laminectomy to debride the fracture site. Whether this operation was ever actually performed during his career is uncertain. Duhamel first demonstrated osteogenesis in 1739 when he showed that new bone surrounded silver wires implanted within the periosteum. During the 19th century, Heine, Fluorens, and Ollier demonstrated the osteogenic capacity of periosteum. Clinical bone transplantation began with the transfer of a free autograft by Walther in 1820 and a free allograft by Macewen in 1878. In the early years of the 20th century, Albee popularized bone grafting in spinal surgery. He published his experiences with 3000 bone graft operations. Bauer investigated the preservation and storage of canine allografts in 1910, and in the 1940s, the storage of autogeneic and allogeneic human bone was reported. After World War II, scientists at the Navy Tissue Bank in Bethesda, Maryland, investigated the preservation, sterilization, and distribution of cadaveric allografts and revealed that the freezing of bone reduces its immunogenicity. 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 anatomical 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 2-column theory of spinal column stability. This classification had a major impact on the understanding of thoracolumbar injuries. In the 1980s, Denis proposed the 3-column theory of spinal instability, which remains widely accepted because of its simplicity and the anatomical 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 rate 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 using these methods countered the perception that these patients' 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. ProblemAccidents are the fourth leading cause of death in the United States after heart disease, cancer, and stroke, annually accounting 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. The thoracolumbar spine and lumbar spine are the most common sites for fractures due to the high mobility of the lumbar spine compared to the more rigid thoracic spine. 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 due to the lack of accurate reporting. 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, 4,200 of them die before reaching the hospital, nearly 5,000 patients develop paraplegia, and an additional 1,500 patients 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. 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 4 of 5 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. FrequencySee Problem. The international rate of spinal fractures is difficult to determine due to 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. In an analysis of patients with osteoporosis in Oviedo, Spain, the prevalence of vertebral fractures varied between 17.4 and 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. 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. EtiologyThe National Spinal Cord Injury Registry, established by Ducker and Perot, reported that 40% of spinal injuries were caused by motor vehicle accidents, 20% by falls, and 40% by gunshot wounds, sporting accidents, industrial accidents, and agricultural accidents combined. 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 1966-1972 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 the south Florida region, gunshot wounds caused 34% of the injuries, and motor vehicle accidents caused only 28%. The remainder of the injuries were attributable to falls (19%), sports- and water-related injuries (8%), and other causes including industrial accidents (12%). Spinous process fractures may occur as a result of direct trauma to the posterior spine, while violent muscular contraction or direct trauma can cause fractures of the transverse processes. Direct trauma also can cause a fracture of an articular process. PathophysiologyThe forces responsible for spinal fractures are compression, flexion, extension, rotation, shear, or distraction forces or a combination of these mechanisms. 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. 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. 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. ClinicalPatients 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, 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 5° of impairment, as follows:
In addition, a detailed neurologic evaluation should include evaluation of sensory level, posterior column function, normal and abnormal reflexes, and examination of rectal tone and perianal sensation. The cutaneous abdominal reflex, bulbocavernosus reflex, anal 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. INDICATIONSSection 3 of 12
Surgical intervention is often necessary 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 depending on the level and degree of injury. 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 timing of decompressive surgery on the rate of neurologic recovery also has remained unclear. 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. Although some evidence suggests that neurologic recovery may be improved with early decompressive surgery (within 48 h after injury), the ideal timing of surgical decompression remains controversial. A variety of operative techniques are used in the treatment of spinal trauma. The surgical approach used is determined by the level of injury, characteristics of the fracture, and location of the neural compression. Modern surgical techniques allow for effective decompression of the neural structures, usually using microsurgical approaches. In patients with unstable fractures, the use of segmental instrumental fixation is often necessary in conjunction with a fusion of the spine, either by an anterior or posterior surgical approach to the spine. This allows for the 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. RELEVANT ANATOMYSection 4 of 12
The lumbar spine consists of a mobile segment of 5 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 compared to 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 2 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. Biomechanics of the lumbosacral spine The lumbar spine is a complex 3-dimensional structure, 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 primarily are 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. CONTRAINDICATIONSSection 5 of 12
Surgery is contraindicated in moribund patients in very poor medical condition. WORKUPSection 6 of 12
Lab Studies
Imaging Studies
Other Tests
TREATMENTSection 7 of 12
Medical therapyInitial 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. 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. 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. Head injuries and extremity fractures commonly accompany vertebral fractures. Abdominal or urological trauma can occur with lumbar fractures, particularly with seatbelt-type injuries. The possible presence of concurrent direct injuries to adjacent intracavitary soft tissue structures, such as 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 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 methylprednisolone (Solu-Medrol) at 30 mg/kg in a bolus, followed by infusion at 5.4 mg/kg/h for 23 hours. The results of a recent 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. For unstable fractures or when neural compression is present, a decompressive procedure with a fusion, usually with instrumentation, becomes necessary. Goals of stabilization are to minimize 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. A 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. 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 middle columns are disrupted. 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. 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. In patients with burst fractures and significant posterior column disruption, anterior and posterior fusion (360°) is indicated. In patients with fracture-dislocation injuries, all 3 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 therapyThe decision to perform surgery in the acute setting is determined 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 relationship between the timing of surgical decompression and 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 associated injuries. Preoperative detailsThe surgical procedure usually is performed under general anesthesia with the patient in a prone, lateral, or knee-elbow position. After the patient is under general anesthesia and the endotracheal tube is 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 under general anesthesia with the patient in the prone position over gel rolls that extend from the shoulders to the lower pelvis, or using a Wilson frame. 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 somatosensorial evoked potential and electromyography 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. Intraoperative detailsSurgical decompression The preferred posterior skin incision is midline. 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 exposing 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. Posterior intertransverse fusion The spine is exposed through a posterior midline incision and subperiosteal muscle dissection. The incision length must be adequate to fully expose the transverse processes. The dissection is carried out laterally over the facet joint to completely expose the transverse processes at the levels to be fused. All soft tissue is meticulously removed from the grafting area, including the transverse process, lateral aspect of the superior facet joints, and pars interarticularis. The bone graft can be harvested 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. Following 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. Posterior interbody fusion Lumbar interbody fusion remains a popular method of arthrodesis because it allows access to the anterior weightbearing spinal column through a standard posterior laminectomy. 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 that 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 heminectomies 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. Anterior corpectomy and fusion 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. Following 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-L5 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 need to be suture ligated in order to reflect 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 using a cross table lateral radiograph. Once the correct level has been exposed, the superior and inferior disks are removed using a long knife, rongeurs, curets, and osteotomes. The vertebral corpectomy is performed using a high-speed drill, curettes, osteotomes and rongeurs with special care when 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. 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. Reported fusion rates and clinical success with anterior interbody techniques are widely variable. Differences probably are related to surgical technique, source of donor bone, patient selection, and method by which determination of fusion was evaluated. Internal fixation and direct current electrical stimulation probably enhance fusion rates. Posterior internal fixation with pedicle screws Internal fixation as an adjunct to spinal fusion has become increasingly popular in recent years. 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 for early patient mobilization, and provides 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. 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. 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. 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 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 2-dimensional scan of the spine performed with an isocentric C arm. Kyphoplasty Compression fractures with an intact posterior cortical wall can be treated by means of a kyphoplasty. It consists of the transpedicular placement of a balloon through a bone biopsy needle and canula into the compressed vertebral body under fluoroscopic guidance. The balloon is then inflated under controlled pressure, resulting in expansion of the vertebral body and creation of a cavity. The cavity created is then filled with bone cement. This procedure results in elevation of the endplate and stabilization the fracture fragments, with a consequent reduction of pain. A posterior cortical defect in a burst fracture is considered a contraindication for kyphoplasty. Postoperative detailsSignificant 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. 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 Complications). 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 combined are used to prevent DVT. If the patient is immobilized from multiple injuries, heparin should be started after the second postoperative day, even in patients who are 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. Follow-upThe fusion is evaluated with plain radiographs, including flexion and extension views, at 6 weeks, 3 months, and 6 months postoperatively. If in doubt, a CT scan is performed. COMPLICATIONSSection 8 of 12
Patients with spinal cord injuries are prone to multiple complications, including decubitus ulcers, pulmonary problems, and urinary sepsis. Occasionally, patients develop delayed progressive neurologic deterioration months to years after sustaining spinal trauma due to instability and progressive spinal deformation. Intraoperative complications 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 leaks. Failure of the fusion 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 Infections can occur following spine surgery, especially following 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 coccus and adjusting according to culture results. All attempts should be made to keep the instrumentation and graft in place until the fusion is solid. Thromboembolic disease 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 following a spinal fracture. Mortality rates 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, 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, options include thrombectomy or a cava vein filter. Stress ulcers 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 prophylaxis measures, such as H2 blockers, sucralfate, and proton pump inhibitors, has reduced the incidence of severe bleeding from stress ulcers. Adynamic ileus and Ogilvie syndrome Ogilvie syndrome, also known as pseudoobstruction 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 conditions 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. Genitourinary complications Urinary complications continue to be significant sources of morbidity following 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. OUTCOME AND PROGNOSISSection 9 of 12
The outcome and prognosis of patients with lumbosacral fractures depends on patients' neurologic condition. Patients with no neurologic deficits or partial deficits generally have a good prognosis, whereas patients with complete injuries remain paraplegic. Other factors, including 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 h of injury) include earlier patient mobilization and probably fewer septic complications related to pneumonia. FUTURE AND CONTROVERSIESSection 10 of 12
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 currently support the fact 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 performed using BMP-2 have demonstrated the same rate of fusion reported in studies performed using autologous iliac crest bone graft, avoiding the morbidity of harvesting iliac crest bone. However, its high cost limits its widespread use. Newer studies are currently 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. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
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