1. • 1. THORACOLUMBAR SPINE Injuries

         

        EPIDEMIOLOGY

     2. Neurologic injury complicates 15% to 20% of fractures at the thoracolumbar level.

     3. Sixty-five percent of thoracolumbar fractures occur as a result of motor vehicle trauma or fall from a height, with the remainder caused by athletic participation and assault.

     4. Most isolated thoracic and lumbar spine fractures are related to osteoporosis and involve minimal or no trauma.

     5. Osteoporosis accounts for approximately 750,000 vertebral fractures annually in the United States and far outnumbers the 15,000 trauma-related thoracic and lumbar spine fractures.

     6. Thoracolumbar trauma occurs most frequently in male patients between 30 and 39 years of age.

     7. Ninety percent of vertebral fractures occur in the thoracolumbar spine.

     8. Neurologic injury occurs in approximately 20% of thoracic and lumbar fractures.

     9. Sixty percent of thoracolumbar fractures occur between T11 and L2 vertebral levels.

        ANATOMY

        See Chapter 8 for a general definition of terms.

     10. The thoracolumbar spine consists of 12 thoracic vertebrae and 5 lumbar vertebrae.

     11. The thoracic level is kyphotic, and the lumbar region is lordotic. The thoracolumbar region, as a transition zone, is especially prone to injury.

     12. The thoracic spine is much stiffer than the lumbar spine in flexion–extension and lateral bending, reflecting the restraining effect of the rib cage as well as the thinner intervertebral discs of the thoracic spine.

     13. Rotation is greater in the thoracic spine, achieving a maximum at T8–T9. The reason is the orientation of the lumbar facets, which limit the rotation arc to approximately 10 degrees for the lumbar spine versus 75 degrees for the thoracic spine.

     14. The conus medullaris ends at the L1–L2 level. The cauda equina, which comprises the motor and sensory roots of the lumbosacral myelomeres (Fig. 10.1), lies caudal to the conus.

          

          

          

     15. The corticospinal tracts demonstrate polarity, with cervical fibers distributed centrally and sacral fibers peripherally.

     16. The ratio of the spinal canal dimensions to the spinal cord dimensions is smallest in the T2–T10 region, which makes this area prone to neurologic injury after trauma.

     17. Neurologic deficits secondary to skeletal injury from the 1st through the 10th thoracic levels are frequently complete deficits, primarily related to spinal cord injury with varying levels of root injury. The proportion of root injury increases with more caudal injuries, with skeletal injuries caudal to L1 causing exclusively root (lower motor neuron) injury.

     18. The region between T2 and T10 is a circulatory watershed area, deriving its proximal blood supply from antegrade vessels in the upper thoracic spine and distally from retrograde flow from

         the purported artery of Adamkiewicz, which can be variably located between T9 and L2.

     19. Most thoracic and lumbar injuries occur within the region between T10 and L2, commonly referred to as the thoracolumbar junction. This increased susceptibility can be explained by a variety of factors. The thoracolumbar junction is a transition zone between the relatively stiff thoracic spine and the more mobile lumbar spine.

         MECHANISM OF INJURY

     20. These generally represent high-energy injuries, typically from motor vehicle accident or falls from a height.

     21. They may represent a combination of flexion, extension, compression, distraction, torsion, and shear.

         CLINICAL EVALUATION

         1. Patient assessment: This involves airway, breathing, circulation, disability, and exposure (ABCDE). Please see also Chapter 9.

         2. Initiate resuscitation: Address life-threatening injuries. Maintain spine immobilization. Watch for neurogenic shock (hypotension and bradycardia).

         3. Evaluate the level of consciousness and neurologic impairment: Glasgow Coma Scale

         4. Assess head, neck, chest, abdominal, pelvic, and extremity injury.

         5. Ascertain the history: Assess the mechanism of injury, witnessed head trauma, movement of extremities/level of consciousness immediately following trauma, etc.

         6. Physical examination

            • Back pain and tenderness

            • Lacerations, abrasions, and contusions on back

            • Abdominal and/or chest ecchymosis from seat belt injury (also suggestive of liver, spleen, or other abdominal injury)

         7. Neurologic examination

            • Cranial nerves

            • Complete motor and sensory examination (Figs. 10.2 and 10.3)

               

               

               

               

               

            • Upper and lower extremity reflexes‌

            • Rectal examination: perianal sensation, rectal tone (Fig. 10.4)

               

               

               

            • Bulbocavernosus reflex (Fig. 10.5)

          

          

          

2. In the alert and cooperative patient, the thoracic and lumbar spine can be “cleared” with the absence of pain or tenderness or distraction mechanism of injury and a normal neurologic examination. Otherwise, imaging is required.

RADIOGRAPHIC EVALUATION

1. Anteroposterior (AP) and lateral views of the thoracic and lumbar spine are obtained.

2. Abnormal widening of the interpedicular distance signifies lateral displacement of vertebral body fragments, typical of burst fractures.

3. Vertebral body height loss can be measured by comparing the height of the injured level with adjacent uninjured vertebrae.

4. Quantification of sagittal plane alignment can be performed using the Cobb method.

5. Chest and abdominal radiographs obtained during the initial trauma survey are not adequate for assessing vertebral column injury.

6. Computed tomography (CT) and/or magnetic resonance imaging (MRI) of the injured area may be obtained to characterize the fracture further, to assess for canal compromise, and to evaluate the degree of neural compression.

7. CT scans provide finer detail of the bony involvement in thoracolumbar injuries, and MRI can be used to evaluate for soft tissue injury to the cord, intervertebral discs, or for posterior ligamentous disruption.

   CLASSIFICATION

   Orthopaedic Trauma Association Classification of Thoracic and Lumbar Spine Injuries

   See Fracture and Dislocation Classification Compendium at http://www.ota.org/compendium/compendium.html.

   McAfee et al.

   Classification is based on the failure mode of the middle osteoligamentous complex (posterior longitudinal ligament, posterior half of vertebral body, and posterior annulus fibrosus).

8. Axial compression

9. Axial distraction

10. Translation within the transverse plane

This led to the following six injury patterns in this classification:

1. Wedge–compression fracture

2. Stable burst fracture

3. Unstable burst fracture

4. Chance fracture

5. Flexion-distraction injury

6. Translational injuries

   McCormack et al.

   • This is a “load-sharing classification.”

   • A point value is assigned to the degree of vertebral body comminution, fracture fragment apposition, and kyphosis. Based on their primary outcome of hardware failure, McCormack et al. concluded that injuries with scores >6 points would be better treated with the addition of anterior column reconstruction to posterior stabilization. A recent study demonstrated very high interobserver and intraobserver reliability of this classification system.

     Thoracolumbar Injury Classification System

   • This is an injury scoring system to categorize lumbar burst fractures by morphology, posterior ligamentous complex disruption, and neurologic involvement rather than by anatomy or injury mechanism (Vaccaro et al., 2005a).

   • Thoracolumbar Injury Classification System (TICS) is designed to grade and predict acute spine stability, risk of future deformity, and progressive neurologic compromise.

   • It facilitates treatment recommendations for surgical or nonoperative management. This system has demonstrated good inter- and intraobserver reliability (Harrop et al., 2006).

   • The most important determinants of stability are neurologic deficit as in incomplete spinal cord injury and involvement of all three columns of the spine.

     Denis

     Minor Spinal Injuries

     Articular process fractures (1%) Transverse process fractures (14%) Spinous process fractures (2%) Pars interarticularis fractures (1%)

     Major Spinal Injuries

     Compression fractures (48%)

     Burst fractures (14%)

     Fracture-dislocations (16%) Seat belt–type injuries (5%)

   • Compression fractures

     • These can be anterior (89%) or lateral (11%).

     • They are rarely associated with neurologic compromise.

     • They are generally stable injuries, although they are considered unstable if associated with loss of >50% vertebral body height, angulation >20 to 30 degrees, or multiple adjacent compression fractures.

     • The middle column remains intact; it may act as a hinge with a posterior column distraction injury (seen with compression in 40% to 50%).

     • Four subtypes are described based on endplate involvement (Fig. 10.6):

       Type A: Fracture of both endplates (16%) Type B: Fracture of superior endplate (62%) Type C: Fracture of inferior endplate (6%) Type D: Both endplates intact (15%)

        

        

        

     • Treatment includes an extension orthosis (Jewett brace or thoracolumbar spinal orthosis) with early ambulation for most fractures, which are stable. Reduction of the wedge kyphosis under conscious sedation and application of an extension body cast (Böhler) remains an option. Unstable fractures (>50% height loss or 20 to 30 degrees of kyphosis in nonosteoporotic bone strongly suggests the possibility of posterior ligament complex disruption, which places the patient at risk of increasing kyphotic deformity or neurologic deficit) may require hyperextension casting or open reduction and internal fixation. Posterior ligamentous injury may be inferred by observing widening of the interspinous distance. MRI is sensitive to presence of posterior interspinous ligament and soft tissue injury. Upper thoracic fractures are not amenable to casting or bracing and require surgical management to prevent significant kyphosis.

   • Burst fractures

     • No direct relationship exists between the percentage of canal compromise and the degree of neurologic injury.

     • The mechanism is compression failure of the anterior and middle columns under an axial load.

     • An association exists between lumbar burst fractures, longitudinal laminar fractures, and neurologic injury.

     • These injuries result in loss of posterior vertebral body height and splaying of pedicles on

       radiographic evaluation.

     • Five types are recognized (Fig. 10.7):

       Type A: Fracture of both endplates (24%) Type B: Fracture of superior endplate (49%) Type C: Fracture of inferior endplate (7%) Type D: Burst rotation (15%)

       Type E: Burst lateral flexion (5%)

        

        

        

     • Treatment may consist of hyperextension casting or bracing if no neurologic compromise exists and the fracture pattern is stable (see compression fractures).

     • Early stabilization is advocated to restore sagittal and coronal plane alignment in cases with:

       • Neurologic deficits

       • Loss of vertebral body height >50%

       • Angulation >20 to 30 degrees

       • Canal compromise of >50%

       • Scoliosis >10 degrees

     • Anterior, posterior, and combined approaches have been used.

     • Posterior surgery relies on indirect decompression via ligamentotaxis and avoids the morbidity of anterior exposure in patients who have concomitant pulmonary or abdominal injuries; it also has shorter operative times and decreased blood loss. Anterior approaches allow for direct decompression. Posterior instrumentation alone cannot directly reconstitute anterior column support and is therefore somewhat weaker in compression than anterior instrumentation. This has led to a higher incidence of progressive kyphosis and instrumentation failure when treating highly comminuted fractures.

     • Instrumentation should provide distraction and extension moments.

     • Harrington rods distract posteriorly, which tends to produce kyphosis, and are thus contraindicated for use in the lower lumbar spine.

     • Laminectomies should not be done without instrument stabilization.

   • Flexion–distraction injuries (Chance fractures, seat belt–type injuries) (Fig. 10.8)

      

      

      

   • Patients are usually neurologically intact.

   • Up to 50% may have associated abdominal injuries.

   • Flexion–distraction injury results in compression failure of the anterior column and tension failure of the posterior and middle columns.

   • Injuries rarely occur through bone alone and are most commonly the result of osseous and

     ligamentous failure.

   • One may see increased interspinous distance on the AP and lateral views.

   • Four types are recognized:

     Type A: One-level bony injury (47%)

     Type B: One-level ligamentous injury (11%)

     Type C: Two-level injury through bony middle column (26%)

     Type D: Two-level injury through ligamentous middle column (16%)

   • Treatment consists of hyperextension casting for type A injuries.

   • For injuries with compromise of the middle and posterior columns with ligamentous disruption (types B, C, and D), posterior spinal fusion with compression should be performed.

   • The primary goal of surgery for flexion–distraction injuries is not to reverse neurologic deficit

     but to restore alignment and stability to enable early patient mobilization and to prevent secondary displacement.

   • Unless a herniated disc is noted on a preoperative MRI and warrants anterior discectomy, posterior reduction and compressive stabilization of the involved segment are usually adequate.

• Fracture-dislocations

  • All three columns fail under compression, tension, rotation, or shear, with translational deformity.

  • Three types, with different mechanisms (Denis), are known as follows:

    Type A: Flexion–rotation: posterior and middle column fail in tension and rotation; anterior column fails in compression and rotation; 75% with neurologic deficits, 52% of these being complete lesions (Fig. 10.9)

    Type B: Shear: shear failure of all three columns, most commonly in the posteroanterior direction; all cases with complete neurologic deficit (Fig. 10.10)

    Type C: Flexion–distraction: tension failure of posterior and middle columns, with anterior tear of annulus fibrosus and stripping of the anterior longitudinal ligament; 75% with neurologic deficits (all incomplete) (Fig. 10.11)

     

     

     

     

     

     

     

     

     

  • Generally, these are highly unstable injuries that require surgical stabilization.‌‌

  • Posterior surgery is usually most useful for achieving reduction and stability in these injuries.

  • The characteristic deformity of fracture-dislocations is translational malalignment of the involved vertebrae. Realigning the spine is often difficult and is best performed by direct manipulation of the vertebra with bone clamps or elevators. Gradual distraction may be needed to reduce dislocations with no associated fracture.

  • Patients whose fractures are stabilized within 3 days of injury have a lower incidence of

    pneumonia and a shorter hospital stay than those with fractures stabilized more than 3 days after injury.

  • Patients without neurologic deficit do not typically need urgent surgery. Surgery can be performed when the patient has been adequately stabilized medically. A similar approach should be employed in patients that have complete neurologic injuries when there is little chance for significant recovery.