AAOS Comprehensive Orthopaedic Review

Section 7 - Spine

Chapter 68. Spinal Trauma

I. Initial Evaluation and Management

A. Initial evaluation and management of patients with spinal injuries is begun in the field by paramedical personnel.

 

1. Treatment of potential spinal injury begins at the accident scene with proper immobilization using a rigid cervical collar, tape, and straps to secure the patient's neck, followed by transport on a firm spine board with lateral support devices.

 

2. In sports-related injuries, helmet and shoulder pads should be left in place until arrival at the hospital, where experienced personnel can perform simultaneous removal of both in a controlled fashion.

 

3. Initial evaluation of a patient with spinal trauma includes the primary survey, resuscitation, and the secondary survey.

 

B. Primary survey

 

1. The primary survey consists of evaluation of the airway, breathing, and circulation (the ABCs of basic trauma life support).

 

2. Protection of the spine and spinal cord is the most important management principle. Maintenance of oxygenation and hemodynamic stability are paramount in attenuating secondary injury to the damaged spinal cord.

 

3. Until proved otherwise, all trauma patients should be assumed to have a spinal injury, especially those with altered mental status or following blunt head trauma.

 

4. Certain histories, mechanisms of injury, and physical clues are associated with particular types of spinal injuries.

 

a. Motorcyclists have a higher incidence of thoracic spinal injuries.

 

b. Abdominal ecchymoses or abrasions from seat belts are associated with flexion-distraction injury of the thoracolumbar spine.

 

c. Every multiple-trauma patient should undergo visual and manual inspection of the back.

 

d. Patients with ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis require extra vigilance because these patients, especially those with ankylosing spondylitis, have an increased risk of fractures and can experience neurologic deterioration secondary to epidural hematoma. Even minor trauma that results in neck or back pain should warrant supplemental CT evaluation in this population.

 

i. Nondisplaced fractures commonly occur in this setting and carry a high rate of delayed or missed diagnosis.

 

ii. These fractures are typically unstable and can lead to spinal cord injury (SCI) if not stabilized appropriately.

 

5. Inadequate initial stabilization can contribute to further neurologic deterioration in a patient with an acute SCI and can significantly worsen eventual outcome. It has been estimated that 3% to 25% of SCIs occur after the initial traumatic episode, during early management or transport.

 

6. When securing an airway, manual in-line immobilization of the head and neck should be maintained whenever immobilization devices are removed.

 

C. Secondary survey

 

1. After the primary survey and resuscitation have been completed, a thorough evaluation of the patient is performed with attention directed to all organ systems.

 

2. In patients with suspected spinal trauma, a thorough neurologic assessment is performed.

 

a. Initial neurologic evaluation assesses only the patient's level of alertness and consciousness.

 

b. A thorough assessment of neurologic status and potential spinal injury is performed during the secondary survey.

 

3. A variety of clinical grading systems has been developed for assessing and reporting neurologic status in spinal cord injury patients.

 

a. The Frankel scale has been supplanted by the American Spinal Injury Association (ASIA) scale (

Figure 1).

 

[Figure 1. ASIA form for standard neurologic classification of SCI.]

b. The most recent version includes separate motor and sensory scores as well as a general impairment scale and incorporates the functional independence measure, a tool that assesses the functional effect of SCI. The motor score has been shown to correlate with potential for functional improvement during rehabilitation.

 

D. Cervical spine clearance

 

1. The optimal algorithm for cervical spine clearance in trauma patients remains controversial.

 

2. Prolonged immobilization in the multiply injured patient is known to be associated with numerous complications, including an increased risk of aspiration, limitation of respiratory function, development of ulcers in the occipital and submandibular areas, and possible increases in intracranial pressure.

 

3. Cervical spine radiographs are not indicated in trauma patients with low-risk mechanisms who are alert and awake and do not have neck pain or tenderness or a history of distracting injuries.

 

4. Cervical spine radiographs are required in trauma patients with neck pain, tenderness, neurologic deficit, altered mental status, or distracting injuries.

 

5. A cervical spine series consisting of AP, lateral, and odontoid views is recommended. Supplemental CT examination is recommended to provide more detail of inadequately visualized levels.

 

a. The most common reason for missing an injury appears to be inadequate visualization of the injured level, most frequently the occipitoatlantoaxial region or cervicothoracic junction.

 

b. Even with adequate plain radiographs, it has been estimated that 15% to 17% of injuries may be missed.

 

6. Following initial plain radiographs and possibly a CT scan, multiple options for determining safe collar removal in symptomatic patients have been proposed.

 

a. A three-view cervical spine series and CT scan has a negative predictive value >99%; in certain instances, this may be sufficient.

 

b. Even if no apparent osseous injury is present, instability can exist, from soft-tissue injury of ligaments, facet capsule, and disks.

 

c. MRI is very sensitive for acute soft-tissue injury and may be an option; however, the incidence of abnormalities on MRI has been shown to be 25% to 40%, suggesting that this modality may be oversensitive.

 

d. Flexion-extension radiographs are frequently obtained to rule out instability.

 

i. In alert and awake patients, active flexion-extension views are safe and no significant complications have been reported.

 

ii. The negative predictive value of plain radiographs in conjunction with flexion-extension views is >99%.

 

7. The most controversial issue is cervical spine clearance in the obtunded patient.

 

a. MRI has been used as an adjunctive test but is limited because of the lack of correlation between MRI findings and clinically significant injury.

 

b. Passive flexion-extension manipulation of the cervical spine under fluoroscopy has been advocated; however, a theoretical risk of iatrogenic SCI from an unrecognized disk herniation exists.

 

c. It has been suggested that many obtunded patients who are at low risk for significant cervical injury can be cleared on the basis of negative radiographs and CT.

 

d. High-risk criteria indicating the need for further evaluation include high-velocity (>35 mph) motor vehicle accidents, any fall from a height of more than 10 feet, closed head injuries, neurologic deficits referable to the cervical spine, and fractures of the pelvis or extremities.



II. Spinal Cord Injury

A. Background

 

1. The annual incidence of SCI is approximately 40 cases per 1 million people in the United States, or 11,000 new cases per year.

 

2. Motor vehicle accidents account for half of reported SCIs. Falls, acts of violence (primarily gunshot wounds), and recreational sport injuries are responsible for most of the remaining SCIs.

 

3. 55% of SCIs occur in the cervical spine. The remaining injuries are equally distributed throughout the thoracic, thoracolumbar, and lumbosacral spine.

 

4. Neurologically, most patients sustain incomplete tetraplegia (34.3%), followed by complete paraplegia (25.1%), complete tetraplegia (22.1%), and incomplete paraplegia (17.5%). Only 1% have complete neurologic recovery at the time of hospital discharge.

 

B. Field evaluation and initial management of SCIs—See Section I.

 

C. Emergency department evaluation

 

1. See Section I.

 

2. The respiratory pattern of the patient with SCI provides information regarding the level of the SCI and the need for ventilatory assistance.

 

a. SCI above C5 is more likely to require intubation.

 

b. Complete quadriplegia is more likely to require intubation than incomplete quadriplegia or paraplegia.

 

3. SCI patients are at risk for hemodynamic and neurogenic shock.

 

a. Neurogenic shock, defined as circulatory collapse resulting from neurologic injury, is caused by an interruption of the sympathetic output to the heart and peripheral vasculature.

 

b. This collapse gives rise to bradycardia (due to the unopposed parasympathetic input to the heart) and loss of vascular and muscle tone below the level of the SCI.

 

4. After initial survey and resuscitation have been completed, patients are examined for signs of obvious injuries to the head, torso, and abdomen.

 

5. A thorough neurologic assessment should be performed.

 

a. The neurologic examination should establish the level of SCI.

 

b. When motor function is absent, sacral sensation is tested to distinguish between complete and incomplete lesions.

 

c. Early neurologic findings may be confounded by spinal shock, defined as a transient acute neurologic syndrome of sensorimotor dysfunction.

 

i. Spinal shock is characterized by flaccid areflexic paralysis and anesthesia.

 

ii. The duration of spinal shock varies, but typically it resolves within 48 hours.

 

iii. The termination of spinal shock marks the onset of spasticity below the level of the SCI.

 

6. Recognition of patterns of neurologic deficits can help determine prognosis (

Figure 2).

a. Brown-Sequard syndrome, also known as spinal cord hemisection, occurs most frequently as a result of penetrating trauma.

 

i. The classic presentation of this syndrome involves ipsilateral paralysis and loss of posterior column function (position sense and

 

[Figure 2. A, Cross-sectional anatomy of the cervical spinal cord showing the ascending and descending tracts and their topographic organization. B, Brown-Sequard syndrome with hemisection of cord. C,Central cord syndrome with injuries to the central portion of the spinal cord affecting the arms more than the legs. D, Anterior cord syndrome with sparing of only the posterior columns of the spinal cord.E, Posterior cord syndrome affects only the posterior columns.]

   vibration) and contralateral loss of spinothalamic function (pain and temperature).

 

ii. This incomplete SCI syndrome carries the best prognosis for recovery of functional motor activity and sphincter control.

 

b. Central cord syndrome is the most common type of incomplete SCI and is usually caused by hyperextension forces applied to a spine in which stenosis is present.

 

i. It is characterized by weakness affecting the upper extremities more than the lower extremities, with deficits worse distally than proximally.

 

ii. Sensory deficits are variable but often include hyperpathia (severe burning dysesthetic pains in the distal upper extremities).

 

c. Anterior cord syndrome is characterized by paraplegia or quadriplegia and a dissociated sensory deficit below the level of the SCI.

 

i. The sensory deficit is caused by injury to the spinothalamic tracts, which mediate pain and temperature sensation, and by preservation of the posterior columns, which mediate two-point discrimination, position sense, and vibration.

 

ii. Anterior cord syndrome carries the worst prognosis of incomplete injuries, with only 10% to 20% of patients recovering functional motor control.

 

7. The ASIA International Standards for Neurologic and Functional Classification of Spinal Cord Injury have been recommended as the preferred neurologic examination tool. The initial ASIA Impairment Scale score is a reliable predictor of long-term outcome of patients with cervical and thoracic SCI.

 

D. Associated injuries

 

1. In 28% of patients, SCI is associated with extraspinal fractures.

 

2. SCI commonly occurs with closed head injuries.

 

3. Noncontiguous spinal fractures are common, ranging from 3% to 23.8%.

 

4. SCI in the cervical region may be associated with vertebral artery injury, particularly in blunt trauma (33%).

 

a. Most patients with unilateral vertebral artery occlusion remain asymptomatic because of the rich collateral blood flow, leading to an under-diagnosis of this entity.

 

b. Injuries commonly associated with vertebral artery injury include high cervical fractures, fractures extending into the transverse foramen, and unilateral and bilateral facet subluxations.

 

c. Magnetic resonance angiography is a noninvasive method of evaluation; however, the only patients for whom evaluation and treatment are currently recommended are those with cervical injuries associated with neurologic deficit attributable to basilar or vertebral artery perfusion. Treatment consists of stent application.

 

E. Initial radiographic assessment—See Section I. D.

 

F. Initial closed reduction

 

1. In conscious patients, early closed reduction of cervical spine fracture-dislocations is safe and effective.

 

a. Traction should cease if the patient's neurologic state worsens or if overdistraction is observed.

 

b. If the deformity has been successfully reduced, or if a determination has been made that closed reduction has failed, the patient is immobilized until definitive treatment.

 

2. The possible presence of a herniated disk fragment at the injury site raises concern that the fragment could cause compression on the spinal cord during reduction of the deformity.

 

a. It is estimated that such a disk fragment occurs in one third to one half of patients. The possible presence of such a fragment has led to controversy concerning the necessity of performing routine MRI in patients with facet dislocations before undertaking closed reduction.

 

b. It is generally accepted that closed reduction can be undertaken before performing MRI to detect a disk herniation in an awake patient who is able to communicate a worsening neurologic deficit.

 

G. Medical management

 

1. Respiratory, cardiac, and hemodynamic monitoring is necessary for SCI patients. Hypotension (systolic blood pressure <90 mm Hg) should be avoided and a mean arterial blood pressure of 85 to 90 mm Hg should be maintained for the first 7 days after acute injury.

 

2. To avoid deep venous thrombosis and pulmonary embolism, in the absence of coagulopathy or hemorrhage, prophylactic use of low-molecular-weight heparin, a rotating bed, and pneumatic compression stockings or combination therapy are recommended.

 

3. Aggressive pulmonary protocols are important tools for preventing other pulmonary complications.

 

4. Infections including pneumonia, urinary tract infections, and skin decubitus ulcers are common in SCI patients and should be treated promptly.

 

H. Pathophysiology and pharmacotherapy

 

1. Injury to the nervous system consists of primary and secondary processes.

 

a. The mechanical forces that affect the spinal column during the traumatic event are imparted to neural tissue, resulting in the primary injury to the spinal cord.

 

b. The injury resulting from the primary event is generally understood to be irreversible.

 

c. Tissue adjacent to the primary injury is not damaged at the time of the trauma but is vulnerable to secondary pathophysiologic processes that may propagate injury.

 

d. Secondary processes include alterations in microvascular perfusion, elaboration of free radicals, lipid peroxidation, necrosis and apoptosis of the cell, and ionic imbalance.

 

2. Current treatment protocols attempt to attenuate these secondary pathophysiologic events.

 

a. Methylprednisolone is indicated for patients with acute, nonpenetrating SCIs who are admitted for treatment within 8 hours of injury, according to the third National Acute Spinal Cord Injury Study (NASCIS III) protocol.

 

i. For patients presenting less than 3 hours after injury, a 30-mg/kg bolus of methylprednisolone is administered, followed by 5.4 mg/kg/h for 23 hours.

 

ii. For patients presenting from 3 to 8 hours after injury, the 30-mg/kg bolus is followed by 5.4 mg/kg/h for the next 47 hours.

 

b. The effective neuroprotective mechanisms of methylprednisolone include inhibition of lipid peroxidation and inflammatory cytokines, modulation of inflammatory cells, improved vascular perfusion, and prevention of calcium channel influx and accumulation.

 

c. NASCIS II and III have made the use of methylprednisolone the standard treatment in clinical practice for patients with SCI, but criticism has recently been directed at the interpretation and conclusions of these studies.

 

i. In NASCIS II, the primary outcome analysis of motor and sensory recovery in all randomized patients was in fact negative. Only after a post hoc analysis was an arguably small yet statistically significant benefit found in patients in whom treatment was started within 8 hours of injury.

 

ii. Similarly, the primary outcome measures in NASCIS III were negative, but post hoc analysis determined that 48 hours of methylprednisolone treatment benefited patients in whom treatment was initiated 3 to 8 hours after injury.

 

d. Systemic administration of monosialotetrahexosylganglioside (GM-1) has been shown to be neuroprotective in a variety of experimental models of the central nervous system.

 

i. A large-scale, multicenter randomized trial did not find that the use of GM-1 yielded better neurologic outcomes.

 

ii. Patients treated with GM-1 did appear to have a more rapid rate of recovery.



III. Cervical Fractures

A. Occipital condyle fractures

 

1. Background and diagnosis

 

a. The awareness of occipital condyle fractures has increased because of greater use of CT evaluation of spine trauma. Sensitivity on plain radiographs for diagnosis is as low as 3%.

 

b. Occipital condyle fractures are associated with an 11% mortality rate from associated injuries and should be considered a marker for potentially lethal trauma.

 

c. Associated cervical spine injury at an additional level occurs in 31% of patients.

 

d. Delayed cranial nerve palsies may develop and typically affect cranial nerves IX, X, and XI.

 

2. Classification

 

a. Type 1 fractures (representing 3% of occipital condyle fractures) are comminuted fractures resulting from axial load.

 

b. Type 2 fractures (22%) involve extension of a basilar skull fracture into the condyle.

 

c. Type 3 fractures (75%) are avulsion fractures and should raise clinical suspicion for an underlying occipitocervical dissociation.

 

3. Treatment

 

a. Occipitocervical dissociation must be ruled out, particularly in patients with type 3 fractures.

 

b. Cervical orthosis

 

B. Occipitocervical dissociation

 

1. Background and diagnosis

 

a. Traumatic occipitocervical dissociation is most often lethal.

 

b. Diagnosis on plain radiographs is challenging because of poor osseous visualization in this area. Common measurements include the Powers ratio and the Harris basion-axial interval-basion-dental interval.

 

i. Powers ratio—Divides the distance from the basion to the posterior arch by the distance from the anterior arch to the opisthion. A ratio >1 suggests possible anterior dislocation.

 

ii. The Harris basion-axial interval-basion-dental interval method is considered to be the most sensitive radiographic measurement. It measures two parameters: the distance from the basion to a line drawn tangentially to the posterior border of C2 (>12 mm

 

[

Figure 3. Illustrations of common atlas fracture patterns. A, Posterior arch fracture. B, Lateral mass fracture. C, Classic burst (Jefferson) fracture. D, Unilateral anterior arch fracture. E, Transverse process fracture. F, Anterior arch avulsion fracture.]

   or <4 mm is abnormal), and the distance from the basion to the odontoid (>12 mm is abnormal).

 

iii. Sensitivity of plain radiographs is approximately 57%, of CT is 84%, and of MRI is 86%. CT and/or MRI is recommended for patients with suspected occipitocervical dissociation.

 

2. Classification

 

a. Type 1 (anterior)

 

b. Type 2 (longitudinal)

 

c. Type 3 (posterior)

 

3. Treatment

 

a. Use of traction should be avoided. It is associated with a 10% rate of neurologic deterioration.

 

b. In patients with survivable injuries, an occipitocervical fusion is recommended.

 

C. Atlas (C1) fractures

 

1. Background and diagnosis

 

a. Atlas fractures constitute 7% of cervical spine fractures.

 

b. Classic Jefferson (burst) fractures are bilateral fractures of the anterior and posterior arches of C1 resulting from axial load (Figure 3).

 

c. Long-term stability depends on the mechanism and healing of the transverse ligament.

 

d. Based on cadaveric data, lateral mass displacement >7 mm (8.1 mm with radiographic magnification) suggests transverse ligament disruption.

 

e. MRI has increased sensitivity in detecting ligamentous disruption.

 

i. Type 1 injuries are midsubstance ruptures of the transverse ligament.

 

ii. Type 2 injuries involve an avulsion fracture of the ligament.

 

2. Treatment

 

a. Isolated anterior and posterior arch fractures, lateral mass fractures, and transverse process fractures of the atlas can be treated nonsurgically, with 6 to 12 weeks of external immobilization.

 

b. Burst fractures involving both the anterior and posterior arches with an intact transverse ligament (<7 mm of combined lateral overhang of lateral masses) are considered stable injuries and can also be treated with external immobilization with a halo.

 

c. Combined lateral mass displacement >7 mm suggests injury to the transverse ligament and an unstable injury.

 

[

Figure 4. Anderson-d'Alonzo classification of odontoid fractures. Type 1 fractures involve the tip of the dens. Type II fractures occur at the base of the dens, at the junction of the dens and the central body of the axis. Type III fractures extend into the body of the dens.]

i. Bed rest with traction to reduce the lateral displacement can be performed.

 

ii. Conversion to a halo vest at 6 weeks is considered if the reduction can be maintained.

 

iii. Surgical options may be considered: Use of C1 lateral mass screws has become widely accepted and allows direct fracture union without sacrificing motion. Occipitocervical fusion is a reasonable option but sacrifices significant motion.

 

D. Axis (C2) fractures

 

1. Background and diagnosis

 

a. Odontoid fractures are the most common type of axis fracture.

 

b. They account for 10% to 15% of all cervical spine fractures.

 

2. Anderson-d'Alonzo classification (Figure 4)

 

a. Type 1 fractures are avulsion fractures of the tip of the odontoid.

 

b. Type 2 fractures occur through the waist of the odontoid process.

 

c. Type 3 fractures extend into the C2 vertebral body.

 

3. Treatment

 

a. Type 1 fractures—These fractures are stable and can be treated with a cervical orthosis once the possibility of an occipitocervical dissociation has been eliminated.

 

b. Type 2 fractures—For these fractures, treatment is largely dependent on fracture characteristics and patient population.

 

i. In elderly patients, halo vest immobilization is poorly tolerated and has poor healing rates. These patients should be considered for early C1-C2 fusion. In patients unable to tolerate surgery, external orthosis may allow fibrous union and adequate stability for routine activities of daily living.

 

ii. In younger, healthy patients, fracture characteristics dictate treatment.

 

(a) Nondisplaced fractures—These fractures should be treated with halo vest immobilization for 6 to 12 weeks. Risk factors for nonunion include fracture comminution, delay in diagnosis, and patient age >50 years. Early surgical treatment may be considered for patients with these risk factors.

 

(b) Fractures in which reduction cannot be achieved or maintained—Surgical treatment should be considered. Anterior odontoid screw placement using the lag technique is an option for minimally comminuted type 2 fractures. For best results, the fracture should be diagnosed early, reduction must be achieved, and patient habitus should allow appropriate screw placement. Otherwise, surgical treatment involves posterior C1-C2 stabilization with varying wiring or screw constructs. More rigid screw constructs may avoid the need for postoperative halo vest immobilization.

 

c. Type 3 fractures—These injuries are typically stable and should be treated with a cervical orthosis for 6 to 12 weeks.

 

E. Traumatic spondylolisthesis of the axis

 

1. Background and diagnosis

 

a. This injury is characterized by bilateral fractures of the pars interarticularis (hangman's fracture).

 

b. The mechanism results from a combination of hyperextension, compression, and rebound flexion.

 

2. Levine and Edwards classification (

Figure 5)

 

a. Type I fractures result from axial compression and hyperextension and demonstrate <3 mm of displacement and no angulation.

 

b. Type II fractures result from hyperextension and axial load followed by rebound flexion and demonstrate translation >3 mm as well as angulation.

 

c. Type IIa fractures are characterized by angulation without significant translation and result from a flexion-distraction injury. Recognition

 

[Figure 5. Illustrations of types of traumatic spondylolisthesis of the axis using the Levine and Edwards modification of the Effendi classification system. A, Type I. B, Type II. C, Type IIA. D, Type III.]

   of type IIa fractures can be difficult but is critical because application of traction can further displace the fracture and should be avoided.

 

d. Type III fractures are type I fractures associated with injury to the C2-3 facet joints, most commonly bilateral facet dislocations. These fractures result from flexion-distraction followed by hyperextension.

 

3. Treatment

 

a. Most patients can be treated successfully with external immobilization in a halo vest or cervical orthosis for 6 to 12 weeks. Up to 5 mm of displacement can occur without disruption of the posterior ligaments or the C2-3 disk.

 

b. Surgical indications include type II fractures with severe angulation, type III fractures with disruption of the C2-3 disk and/or facet dislocation, or inability to achieve or maintain fracture reduction. Surgical options include C2-C3 interbody fusion, posterior C1-C3 fusion, or bilateral C2 pars interarticularis screws.

 

F. Fractures and dislocations of the subaxial spine (C3 through C7)

 

1. Classification

 

a. The most commonly used classification system for subaxial spine trauma is the Allen-Ferguson system (

Figure 6).

 

b. Six distinct classes are described, based on mechanism of injury, with each class subdivided into stages of progressive severity.

 

i. The three most commonly observed categories are compressive flexion, distractive flexion, and compression extension.

 

ii. Less common is vertical compression.

 

iii. The least common categories are distractive extension and lateral flexion.

 

2. Treatment of common injury patterns

 

a. Axial load injuries include compression fractures, burst fractures, and teardrop fractures.

 

i. Compression fractures are caused by axial loading in flexion with failure of the anterior half of the body without disruption of the posterior body cortex and minimal risk of neurologic injury. Most of these injuries are treated with external immobilization for 6 to 12 weeks. Fusion to prevent kyphosis may be considered if angulation exceeds 11° or if there is >25% loss of vertebral body height.

 

ii. Cervical burst fractures are caused by severe compressive load. These fractures are commonly associated with complete and incomplete SCIs from retropulsion of fracture fragments into the spinal canal. Treatment of cervical burst fractures is dictated by neurologic status. Patients with neurologic deficit are best treated by anterior decompression and reconstruction with strut grafts and plating. If significant posterior injury is present, supplemental posterior fusion and instrumentation is necessary.

 

iii. Teardrop fractures should be distinguished from the relatively benign teardrop avulsion, which represents a relatively minor extension injury with a small fleck of bone off the anterior end plate by the annular attachment and may be treated in a cervical orthosis for 6 weeks. The teardrop fracture is a flexion axial load injury characterized by a fracture of the anteroinferior portion of a vertebra as it is driven caudally and into flexion, causing retropulsion of the remaining vertebral body into the spinal canal. Treatment of teardrop fractures is similar to cervical burst fractures.

 

[Figure 6. Allen-Ferguson classification of subaxial cervical fractures. A, Compressive flexion injury. Stage 1, blunting and rounding off of anterosuperior vertebral margin; stage 2, loss of anterior height of the vertebral body and beaklike appearance anteroinferiorly; stage 3, fracture line from the anterior surface of the vertebral body extending obliquely through the subchondral plate with fracture of the beak; stage 4, <3 mm of displacement of the posteroinferior vertebral margin into the spinal canal; and stage 5, >3 mm of displacement of the posterior part of the body. B, Vertical compression injury. Stage 1, fracture of either the superior or inferior end plate causing a central cupping of the end plate; stage 2, fracture of both end plates; and stage 3, fragmentation and displacement of the vertebral body. C,Distractive flexion injury. Stage 1, facet subluxation in flexion and widening of the interspinous distance; stage 2, unilateral facet dislocation; stage 3, bilateral facet dislocation with <50% anterior vertebral body translation; and stage 4, bilateral facet dislocation with 100% anterior translation of the vertebral body. D, Compressive extension injury. Stage 1, unilateral vertebral arch fracture (1A, articular process; 1B, pedicle fracture; 1C, lamina fracture); stage 2, bilaminar fractures; stage 3, bilateral fractures of the vertebral arches and partial anterior vertebral body displacement; stage 4, further anterior vertebral body displacement; and stage 5, 100% translation of the anterior vertebral body. E, Distractive extension injury. Stage 1, failure of the anterior ligamentous complex with possible widening of the disk space and teardrop fracture and stage 2, posterior displacement of the upper vertebral body. F, Lateral flexion injury. Stage 1, asymmetric compression fracture of the vertebral body with associated ipsilateral vertebral arch fracture; and stage 2, displacement of ipsilateral arch fracture.]

   

 

b. Facet fracture-dislocations

 

i. The general consensus is that, regardless of neurologic deficit, the aware, alert patient can safely undergo closed reduction with progressive traction. Patients should be closely monitored with serial neurologic examinations. Development of new or worsening neurologic deficits is an indication to cease closed reduction.

 

ii. MRI is warranted in patients who have failed closed reduction and in obtunded patients. Patients who have undergone successful awake reduction should also undergo an MRI to verify that no disk material or hematoma remains. If significant disk herniation is present, anterior decompression should be performed before definitive posterior reduction and/or stabilization.

 

iii. Once reduced, the fracture-dislocation is stabilized.

 

(a) Unilateral facet dislocations—These dislocations can be stable in the reduced position and may autofuse with a period of immobilization (12 weeks), but they should be followed closely.

 

(b) Bilateral facet dislocations—Surgical stabilization is standard treatment. Posterior procedures have been preferred because they best treat biomechanically and anatomically the injured structure. The anterior approach has been shown to achieve adequate clinical stability with newer plating systems. Currently, posterior and anterior approaches are viable alternatives.



IV. Thoracolumbar Fractures

A. Background

 

1. Injuries to the thoracolumbar spine are usually the result of significant blunt trauma.

 

2. Fractures in the thoracolumbar spine (T11 through L2) are most common and represent more than 50% of all thoracic and lumbar fractures.

 

3. The increased incidence of fractures of the thoracolumbar junction is the result of its location at the biomechanical transition zone between the rigid thoracic rib cage and the more flexible lumbar spine.

 

4. Once a thoracolumbar spine injury fracture has been detected, the remaining spine should be imaged to rule out noncontiguous spinal injury, which may be as high as 12%.

 

[

Figure 7. The three columns of the lumbar spine.]

B. Classification

 

1. Many classification systems for thoracolumbar injuries have been proposed, but no universally accepted system currently exists.

 

2. The Denis and AO classification systems are commonly used.

 

a. Denis classification system—This system divides the spine into three columns (Figure 7) and classifies injuries into minor and major categories on the basis of radiographic and CT imaging. Minor injuries include fractures of the transverse and spinous processes, lamina, and pars interarticularis. Major injuries include compression fractures, burst fractures, flexion-distraction injuries, and fracture-dislocations.

 

i. Compression injuries are defined as fractures of the anterior column with an intact middle column. The posterior column may be disrupted in tension, depending on the degree of loss of anterior vertebral height (>50%).

 

ii. Burst fractures occur as a result of an axial load to the anterior and middle column, leading to divergent spread of the pedicles and retropulsion of bone into the spinal canal.

 

iii. Flexion-distraction injury is the classic "seat belt injury," with failure of the middle and posterior columns and preservation or compressive failure of the anterior column, depending on the location of the axis of rotation. Abdominal visceral injuries are commonly associated with flexion distraction injuries in the thoracolumbar spine, occurring in 50% of these patients.

 

iv. Fracture-dislocations involve failure of all three columns following compression, tension, rotation, or shear forces. They are associated with the greatest incidence of neurologic deficit and are unstable.

 

b. AO classification—This is a comprehensive classification system that divides thoracolumbar spinal fractures into three general groups.

 

i. Type A fractures (compression injuries)

 

ii. Type B fractures (distraction injuries)

 

iii. Type C fractures (torsional injuries)

 

iv. Fractures are further subdivided based on fracture morphology, bony versus ligamentous failure, and the direction of displacement.

 

C. Treatment

 

1. The treatment of most patients with thoracolumbar fractures is nonsurgical.

 

a. Patients who are neurologically intact; who have <25° kyphosis, <50% loss of vertebral height, and <50% canal compromise; and who have an intact posterior ligamentous complex are the best candidates for nonsurgical treatment.

 

b. These patients may be treated with a hyperextension thoracolumbar orthosis or casting for 3 months.

 

2. Surgical treatment is indicated for unstable fractures and/or patients with neurologic deficits.

 

a. For patients with incomplete neurologic deficits and ongoing spinal cord compression from retropulsed fragments, anterior decompression and stabilization is typically required.

 

i. Adjunctive posterior stabilization may be necessary in injuries with posterior column involvement.

 

ii. Early stabilization of patients with neurologic injuries allows for early rehabilitation and improved outcomes.

 

b. Patients with unstable burst fractures that include failure of the posterior ligamentous complex, fracture-dislocations, and/or fractures with significant rotational displacement should undergo initial posterior stabilization. If canal clearance from reduction and ligamentotaxis is not adequate, staged anterior decompression and reconstruction is warranted.



V. Lumbosacral Fractures

A. Lower lumbar fractures

 

1. Fractures of the lower lumbar spine (L3 through L5) are less common than thoracolumbar fractures.

 

a. The lower lumbar spine is lordotic in the sagittal plane, placing the weight-bearing axis through the middle and posterior columns, making this area more instrinsically stable.

 

b. The facets are aligned along the sagittal plane, which can tolerate greater flexion-extension moments before failure.

 

c. The lumbosacral junction is situated deep in the pelvis and can withstand large forces transmitted across it.

 

2. This region has a greater ability to tolerate flexion moments, so anterior column failure (compression fracture) should raise the suspicion of posterior ligamentous injury, especially if >50% loss of vertebral height is seen.

 

3. Burst fractures are more common than compression fractures because the load-bearing axis is more posterior.

 

a. Most injuries occur with the spine in neutral position, resulting in axial loading of the anterior and middle columns.

 

b. Varying amounts of retropulsion may be encountered; however, the incidence of significant and permanent neurologic deficit is much lower than in the upper spine because the spinal cord ends above this level and the cauda equina and nerve roots are more tolerant of compression.

 

4. Flexion-distraction injuries account for fewer than 10% of lumbar spine fractures.

 

a. These fractures are most common from L2 through L4 because at L5 the pelvic and iliolumbar ligaments impart stability.

 

b. A large flexion moment causes flexion of the upper lumbar segments, whereas the lower segments are stabilized, resulting in posterior element failure in tension.

 

5. Treatment

 

a. Most patients with lower lumbar fractures can be treated nonsurgically, with a short course of bed rest followed by immobilization in a thoracolumbosacral orthosis for 12 weeks.

 

b. A single-leg spica attachment may be necessary for fractures of L4 and L5 to control the lumbosacral junction.

 

c. Patients who have cauda equina syndrome or significant neurologic deficit with severe canal compromise should be considered for surgical decompression and stabilization.

 

i. Decompression can typically be performed through a posterior approach via a laminectomy and restoration of sagittal balance.

 

ii. Fixation extends one level above and below the injury.

 

B. Sacral spine fractures

 

1. Sacral fractures are usually the result of high-energy trauma and rarely occur in isolation; additional pelvic and spine injuries should be investigated.

 

2. Fractures of the sacrum may be vertical (most common), transverse, or oblique.

 

3. The Denis classification divides the sacrum into three zones.

 

a. Zone 1 extends from the sacral ala to the lateral border of the neural foramen.

 

b. Zone 2 represents the neuroforamen.

 

c. Zone 3 involves the middle sacrum and canal.

 

4. Sacral fractures are often associated with root deficits because the sacral roots are tethered and restricted along bony tunnels, limiting their mobility.

 

5. The direction of the fracture line and the zone of fracture determine the likelihood of neurologic injury.

 

a. Zone 1 fractures are the most common sacral fractures, are vertical or oblique, and result in neurologic deficits in 6% of patients.

 

b. Zone 2 fractures represent 36% of sacral fractures, are vertical or oblique, and result in neurologic deficit in 30% of patients. Because these deficits are unilateral, the patient will have normal bowel and bladder function.

 

c. Zone 3 fractures are least common, are horizontal or vertical, and carry a 60% chance of neurologic deficit with involvement of bilateral sacral roots, resulting in bowel, bladder, and sexual dysfunction.

 

6. Treatment

 

a. Appropriate treatment depends on the location and pattern of the fracture, the presence of impaction, the integrity of the L5-S1 facet, associated pelvic fractures, and neurologic deficit.

 

b. Any vertical sacral fracture that is impacted and without vertical shift or limb-length discrepancy can be treated with a trial of nonsurgical care because the impaction provides some stability to the fracture and pelvic ring.

 

c. Treatment of zone 1 displaced fractures should address the anterior pelvic ring, followed by percutaneous iliosacral screw fixation.

 

d. Treatment of zone 2 displaced fractures is similar to zone 1 injuries; however, to avoid further injury to the sacral root, iliosacral screws should not be placed in compression.

 

i. If compression persists after stabilization, posterior decompression is warranted.

 

ii. In highly unstable injuries with significant comminution or displacement, or in injuries with L5-S1 joint disruption, spinopelvic fixation should be considered.

 

e. Zone 3 injuries commonly involve open-book pelvic fracture patterns with diastasis anteriorly and gapping of the sacral fracture posteriorly.

 

i. Initial treatment should address the anterior pelvic ring disruption followed by posterior screw fixation if necessary.

 

ii. Indications for spinopelvic fixation include presence of vertical shear or disruption of the L5-S1 facets.



Bibliography

Allen BL Jr, Ferguson RL, Lehman TR, O'Brien RP: A mechanistic classification of closed, indirect fractures and dislocations of the lower cervical spine. Spine 1982;7:1-27.

Bohlman HH: Acute fractures and dislocations of the cervical spine: An analysis of three hundred hospitalized patients and review of the literature. J Bone Joint Surg Am 1979;61:1119-1142.

Bracken MB, Shepard MJ, Holford TR, et al: Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury: Results of the third national acute spinal cord injury study. JAMA 1997;277:1597-1604.

Denis F: Instability as defined by the three-column spine concept in acute spinal trauma. Clin Orthop Relat Res 1984;189: 65-76.

Denis F, Davis S, Comfort T: Sacral fractures: An important problem: Retrospective analysis of 236 cases. Clin Orthop Relat Res 1988;227:67-81.

Ghanayem AJ, Zdeblick TA: Anterior instrumentation in the management of thoracolumbar burst fractures. Clin Orthop Relat Res 1997;335:89-100.

Guidelines for management of acute cervical spinal injuries. Neurosurgery 2002;50(suppl 3):S1.

Johnson MG, Fisher CG, Boyd M, Pitzen T, Oxland TR, Dvorak MF: The radiographic failure of single segment anterior cervical plate fixation in traumatic cervical flexion distraction injuries. Spine2004;29:2815-2820.

Koivikko MP, Kiuru MJ, Koshinen SK, Myllynen P, Santavirta S, Kivisaari L: Factors associated with nonunion in conservatively-treated type-II fractures of the odontoid process. J Bone Joint Surg Br2004;86:1146-1151.

Mirza SK, Mirza AJ, Chapman JR, Anderson PA: Classifications of thoracic and lumbar fractures: Rationale and supporting data. J Am Acad Orthop Surg 2002;10:364-377.

Noojin F, Malkani A, Haikal L, Lundquist C, Voor M: Cross-sectional geometry of the sacral ala for safe insertion of iliosacral screws: A computed tomography mode. J Orthop Trauma 2000;14:31-35.

Sekhon LH, Fehlings MG: Epidemiology, demographics, and pathophysiology of acute spinal cord injury. Spine 2001;26 (suppl 24):S2-S12.

Vaccaro AR, Falatyn SP, Flanders AE, Balderston RA, Northrup BE, Cotler JM: Magnetic resonance evaluation of the intervertebral disc, spinal ligaments, and spinal cord before and after closed traction reduction of cervical spine dislocations. Spine 1998;23:789-794.

Vaccaro AR, Kim DH, Brodke DS, et al: Diagnosis and management of sacral spine fractures. Instr Course Lect 2004;53: 375-385.

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Top Testing Facts

1. Patients with ankylosing spondylitis have increased risk of spinal fractures with minor trauma and can experience neurologic deterioration secondary to epidural hematoma.

 

2. Noncontiguous spine injuries can occur in up to 24% of patients and are common in the presence of head injury, upper cervical injury, and cervicothoracic injury.

 

3. Brown-Sequard syndrome has the best prognosis for ambulation, central cord syndrome has a variable recovery, and anterior cord syndrome has the worst prognosis.

 

4. In patients with SCI, hypotension (systolic blood pressure <90 mm Hg) should be avoided and mean arterial blood pressure at 85 to 90 mm Hg should be maintained to prevent secondary SCI.

 

5. According to the third national acute spinal cord injury study (NASCIS III), if the time from injury to treatment is less than 3 hours, the protocol is a 30-mg/kg bolus of methylprednisolone followed by 5.4 mg/kg/h for 23 hours. If the time from injury is between 3 and 8 hours, the infusion is continued at 5.4 mg/kg/h for an additional 23 hours (48 hours total).

 

6. In C1 fractures, if both lateral masses are significantly displaced and >7 mm of combined lateral overhang is present, it is likely that the transverse ligament is disrupted.

 

7. An intact posterior ligamentous complex should be considered a prerequisite for nonsurgical care of a burst fracture.

 

8. Type 2A hangman's fractures (traumatic spondylolisthesis) exhibit flexion with little translation and can overdistract with minimal force; traction should be avoided when this fracture pattern is recognized.

 

9. Abdominal visceral injuries are commonly (50%) associated with flexion-distraction injuries in the thoracolumbar spine.

 

10. Most lower lumbar spine fractures can be treated nonsurgically with excellent results.