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Thoracolumbar Spine

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Ovid: Handbook of Fractures

Authors: Koval, Kenneth J.; Zuckerman, Joseph D.
Title: Handbook of Fractures, 3rd Edition
> Table of Contents > II – Axial Skeleton Fractures > 10 – Thoracolumbar Spine

10
Thoracolumbar Spine
EPIDEMIOLOGY
  • Neurologic injury complicates 15% to 20% of fracture at the thoracolumbar level.
  • 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.
  • Recent data have indicated that
    motorcycle accidents are associated with a greater chance of severe and
    multiple level spinal column injuries than other types of vehicular
    trauma.
ANATOMY
See Chapter 8 for a general definition of terms.
  • The thoracolumbar spine consists of 12 thoracic vertebrae and 5 lumbar vertebrae.
  • The thoracic level is kyphotic, the
    lumbar region lordotic. The thoracolumbar region, as a transition zone,
    is especially prone to injury.
  • 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.
  • 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.
  • The conus medullaris is found at the
    L1-L2 level. Caudal to this is the cauda equina, which comprises the
    motor and sensory roots of the lumbosacral myelomeres (Fig. 10.1).
  • The corticospinal tracts demonstrate polarity, with cervical fibers distributed centrally and sacral fibers peripherally.
  • 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.
  • Neurologic deficits secondary to skeletal
    injury from the first through the tenth 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
    entirely root injury.
  • 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 artery of Adamkiewicz, which can be variably
    located between T9 to L2.
  • Most thoracic and lumbar injuries occur
    within the region between T11 and L1, commonly referred to as the
    thoracolumbar junction. This increased susceptibility can be explained
    by a variety of factors. The thoracolumbar junction is a transition

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    zone between the relatively stiff thoracic spine and the more mobile lumbar spine.

Figure 10.1. The relationship between myelomeres (spinal cord segments) and the vertebral bodies.

(From Benson DR, Keenen TL. Evaluation and treatment of trauma to the vertebral column. Instr Course Lect 1990;39:577.)

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MECHANISM OF INJURY
  • These generally represent high-energy injuries, typically from motor vehicle accident or falls from a height.
  • They may represent a combination of flexion, extension, compression, distraction, torsion, and shear.
CLINICAL EVALUATION
  • Patient assessment: This involves airway, breathing, circulation, disability, and exposure (ABCDE).
  • Initiate resuscitation: Address
    life-threatening injuries. Maintain spine immobilization. Watch for
    neurogenic shock (hypotension and bradycardia).
  • Evaluate the level of consciousness and neurologic impairment: Glasgow Coma Scale.
  • Assess head, neck, chest, abdominal, pelvic, extremity injury.
  • Ascertain the history: mechanism of
    injury, witnessed head trauma, movement of extremities/level of
    consciousness immediately following trauma, etc.
  • 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)
  • Neurologic examination
    • Cranial nerves
    • Complete motor and sensory examination (Figs. 10.2 and 10.3)
    • Upper and lower extremity reflexes
      Figure
      10.2. A screening examination of the lower extremities assesses the
      motor function of the lumbar and first sacral nerve roots: hip
      adductors, L1-L2; knee extension, L3-L4; knee flexion, L5-S1; great toe
      extension, L5; and great toe flexion, S1.

      (From Benson DR, Keenen TL. Evaluation and treatment of trauma to the vertebral column. Instr Course Lect 1990;39:583.)
    • Rectal examination: perianal sensation, rectal tone (Fig. 10.4)
      Figure
      10.3. A pain and temperature dermatome chart. These sensory modalities
      are mediated by the lateral spinothalamic tract. Note that C4 includes
      the upper chest just superior to T2. The rest of the cervical and T1
      roots are located in the upper extremities. There is overlap in the
      territories subserved by each sensory root and variation among
      individuals.

      (From Benson DR, Keenen TL. Evaluation and treatment of trauma to the vertebral column. Instr Course Lect 1990;39:584.)
    • Bulbocavernosus reflex (Fig. 10.5)
  • 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
  • Anteroposterior (AP) and lateral views of the thoracic and lumbar spine are obtained.
  • Abnormal widening of the interpedicular
    distance signifies lateral displacement of vertebral body fragments,
    typical of burst fractures.
  • Vertebral body height loss can be measured by comparing the height of the injured level with adjacent uninjured vertebrae.
    Figure 10.4. Sacral sparing may include the triad of perianal sensation, rectal tone, and great toe flexion.

    (From Benson DR, Keenen TL. Evaluation and treatment of trauma to the vertebral column. Instr Course Lect 1990;39:580.)
    Figure
    10.5. The bulbocavernosus reflex arc is mediated by the conus
    medullaris and the lower three sacral roots. Stimulation of the glans
    penis, glans clitoris, or gentle traction on a Foley catheter to
    stimulate the bladder will evoke contraction of the rectal sphincter.

    (From Benson DR, Keenen TL. Evaluation and treatment of trauma to the vertebral column. Instr Course Lect 1990;39:578.)

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  • Quantification of sagittal plane alignment can be performed using the Cobb method.
  • Chest and abdominal radiographs obtained
    during the initial trauma survey are not adequate for assessing
    vertebral column injury.
  • Computed tomography (CT) and/or magnetic
    resonance imaging 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.
  • 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
OTA Classification of Thoracic and Lumbar Spine Injuries
See Fracture and Dislocation Compendium at http://www.ota.org/compendium/index.htm.
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)
  • Axial compression
  • Axial distraction
  • Translation within the transverse plane
This led to the following six injury patterns in this classification:
  • Wedge-compression fracture.
  • Stable burst fracture.
  • Unstable burst fracture.
  • Chance fracture.
  • Flexion-distraction injury.
  • 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 greater than 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.
Denis
Minor Spinal Injuries
  • Articular process fractures (1%)
  • Transverse process fractures (14%)
  • Spinous process fractures (2%)
  • Pars interarticularis fractures (1%)

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Major Spinal Injuries
Figure 10.6. Compression fractures.

(From Browner BD, Jupiter JD, Levine MA, eds. Skeletal Trauma. Philadelphia: WB Saunders, 1992:746.)
  • 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. Unstable fractures (>50%
      height loss or 20 to 30 degrees of kyphosis in nonosteoporotic

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      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. Upper thoracic fractures are not
      amenable to casting or bracing and require surgical management to
      prevent significant kyphosis.

      Figure
      10.7. (A–E) Denis classification of burst fractures. Type A involves
      fractures of both endplates, type B involves fractures of the superior
      endplate, and type C involves fractures of the inferior endplate. Type
      D is a combination of a type A fracture with rotation. Type E fractures
      exhibit lateral translation.

      (From Bucholz RW, Heckman JD, Court-Brown C, et al., eds. Rockwood and Green’s Fractures in Adults, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2006.)
  • 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 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 the superior endplate (49%)
      Type C: Fracture of inferior endplate (7%)
      Type D: Burst rotation (15%)
      Type E: Burst lateral flexion (5%)

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    • Treatment may consist of hyperextension casting if no neurologic compromise exists and the fracture pattern is stable (see compression fractures, earlier).
    • 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 lead to a higher incidence of progressive
      kyphosis and instrumentation failure when treating highly comminuted
      fractures.
    • Instrumentation should provide distraction and extension moments.
    • Harrington rods tend 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).
    • 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. (Fig. 10.8).
    • 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,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.

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    • 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.
      Figure
      10.8. Flexion-distraction injuries. The bony Chance fracture (A) is
      often associated with lap seat-belt use. This fracture was originally
      described by Bohler years before Chance. A flexiondistraction injury
      can occur entirely through soft tissue (B).

      (From Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 5th ed. Baltimore: Lippincott Williams & Wilkins, 2002.)
  • 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)
      Figure 10.9. A flexion-rotation type of fracture-dislocation.

      (From Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 5th ed. Baltimore: Lippincott Williams & Wilkins, 2002.)
      Figure
      10.10. A posteroanterior (A) shear-type fracture-dislocation. An
      anteroposterior (B) shear-type fracture-dislocation. This nomenclature
      is based on the direction of the shear force that would produce the
      injury when applied to the superior vertebra.

      (From Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 5th ed. Baltimore: Lippincott Williams & Wilkins, 2002.)

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    • 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

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      should be employed in patients that have complete neurologic injuries when there is little chance for significant recovery.

      Figure 10.11. A flexiondistraction type of dislocation.

      (From Bucholz RW, Heckman JD, eds. Rockwood and Green’s Fractures in Adults, 5th ed. Baltimore: Lippincott Williams & Wilkins, 2002.)
SPINAL STABILITY
A spinal injury is considered unstable if normal
physiologic loads cause further neurologic damage, chronic pain, and
unacceptable deformity.
White and Panjabi
Defined scoring criteria have been developed for the assessment of clinical instability of spine fractures (Tables 10.1 and 10.2).
Table 10.1. Thoracic and thoracolumbar spine stability scale
Element Point Value
Anterior elements unable to function 2
Posterior elements unable to function 2
Disruptions of costovertebral articulations 1
Radiographic criteria 4
Sagittal displacement >2.5 mm (2 pts)  
Relative sagittal plane angulation >5 degrees (2 pts)  
Spinal cord or cauda equina damage 2
Dangerous loading anticipated 1
Instability: total of ≥5 points.
From White A, Punjabi M. Clinical Biomechanics of the Spine. Philadelphia: JB Lippincott, 1990:335.
Table 10.2. Lumbar spine stability scale
Element Point Value
Anterior elements unable to function 2
Posterior elements unable to function 2
Radiographic criteria 4
Flexion/extension x-rays  
Sagittal plane translation >4.5 mm or 15% (2 pts)
Sagittal plane rotation (2 pts)
>15 degrees at L1-2, L2-3, and L3-4
>20 degrees at L4-5
>25 degrees at L5-S1
OR
Resting x-rays
Sagittal plane displacement >4.5 mm or 15% (2 pts)
Relative sagittal plane angulation >22 degrees (2 pts)
Spinal cord or cauda equina damage 2
Cauda equina damage 3
Dangerous loading anticipated 1
Instability: total of ≥5 points.
From White A, Punjabi M. Clinical Biomechanics of the Spine. Philadelphia: JB Lippincott, 1990:335.
Denis
The three-column model of spinal stability (Fig. 10.12 and Table 10.3) is as follows:
Table 10.3. Basic types of spinal fractures and columns involved in each
Type of Fracture Column Involvement
Anterior Middle Posterior
Compression Compression None None or distraction (in severe fractures)
Burst Compression Compression None or distraction
Seat belt None or compression Distraction Distraction
Fracture-dislocation Compression and/or anterior rotation, shear Distraction and/or rotation, shear Distraction and/or rotation, shear
From Denis F. The three-column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine 1983;8:817–831.
  • Anterior column: anterior longitudinal ligament, anterior half of the vertebral body, and anterior annulus
  • Middle column: posterior half of vertebral body, posterior annulus, and posterior longitudinal ligament
  • Posterior column: posterior neural arches
    (pedicles, facets, and laminae, and posterior ligamentous complex
    (supraspinous ligament, interspinous ligament, ligamentum flavum, and
    facet capsules)
  • Instability exists with disruption of any two of the three columns
  • Thoracolumbar stability usually follows the middle column: if it is intact, then the injury is usually stable.
Three degrees of instability are recognized:
  • First degree (mechanical instability): potential for late kyphosis
    • Severe compression fractures
    • Seat belt–type injuries

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  • Second degree (neurologic instability): potential for late neurologic injury
    • Burst fractures without neurologic deficit
  • Third degree (mechanical and neurologic instability)
    • Fracture-dislocations
    • Severe burst fractures with neurologic deficit
McAfee
This author noted that burst fractures can be unstable,
with early progression of neurologic deficits and spinal deformity as
well as late onset of neurologic deficits and mechanical back pain.
  • Factors indicative of instability in burst fractures:
    • >50% canal compromise
    • >15 to 25 degrees of kyphosis
    • >40% loss of anterior body height
GUNSHOT WOUNDS
  • In general, fractures associated with
    low-velocity gunshot wounds are stable fractures. This is the case with
    most handgun injuries. They are associated with a low infection rate
    and can

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    be
    prophylactically treated with 48 hours of a broad-spectrum antibiotic.
    Transintestinal gunshot wounds require special attention. In these
    cases, the bullet passes through the colon, intestine, or stomach
    before passing through the spine. These injuries carry a significantly
    higher rate of infection. Broad-spectrum antibiotics should be
    continued for 7 to 14 days. High-energy wounds, as caused by a rifle or
    military assault weapon, require open debridement and stabilization.

    Figure
    10.12. The three columns of the spine, as proposed by Francis Denis.
    The anterior column (A) consists of the anterior longitudinal ligament,
    anterior part of the vertebral body, and the anterior portion of the
    annulus fibrosis. The middle column (B) consists of the posterior
    longitudinal ligament, posterior part of the vertebral body, and
    posterior portion of the annulus. The posterior column (C) consists of
    the bony and ligamentous posterior elements.

    (Modified from Denis F. The three-column spine and its significance in the classification of acute thoracolumbar spine injuries. Spine 1983;8:817–831.)
  • Neural injury is often secondary to a
    blast effect in which the energy of the bullet is absorbed and
    transmitted to the soft tissues. Because of this unique mechanism,
    decompression is rarely indicated. One exception is when a bullet
    fragment is found in the spinal canal between the level of T12 and L5
    in the presence of a neurologic deficit. Rarely, delayed bullet
    extraction may be indicated for lead toxicity or late neurologic
    deficits owing to migration of a bullet fragment. Steroids after
    gunshot wounds to the spine are not recommended, because they have
    demonstrated no neurologic benefit and appear to be associated with a
    higher rate of nonspinal complications.

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PROGNOSIS AND NEUROLOGIC RECOVERY
Bradford and McBride
  • These authors modified the Frankel
    grading system of neurologic injury for thoracolumbar injuries,
    dividing Frankel D types (impaired but functional motor function) based
    on degree of motor function as well as bowel and bladder function:

    Type A: Complete motor and sensory loss
    Type B: Preserved sensation, no voluntary motor
    Type C: Preserved motor, nonfunctional
    Type D1: Low-functional motor (3+/5+) and/or bowel or bladder paralysis
    Type D2: Midfunctional motor (3+ to 4+/5+) and/or neurogenic bowel or bladder dysfunction
    Type D3: High-functional motor (4+/5+) and normal voluntary bowel or bladder function
    Type E: Complete motor and sensory function normal
  • In patients with thoracolumbar spine
    fractures and incomplete neurologic injuries, greater neurologic
    improvement (including return of sphincter control) was found in
    patients treated by anterior spinal decompression versus posterior or
    lateral spinal decompression.
Dall and Stauffer
  • They prospectively examined neurologic
    injury and recovery patterns for T12-L1 burst fractures with partial
    paralysis and >30% initial canal compromise.

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  • Conclusions
    • Severity of neurologic injury did not correlate with fracture pattern or amount of CT measured canal compromise.
    • Neurologic recovery did not correlate with the treatment method or amount of canal decompression.
    • Neurologic recovery did correlate with the initial fracture pattern (four types):

      Type I: <15 degrees of kyphosis; maximal canal compromise at level of ligamentum flavum
      Type II: <15 degrees of kyphosis; maximal compromise at the bony posterior arch
      Type III: >15 degrees of kyphosis; maximal compromise at the bony arch
      Type IV: >15 degrees of kyphosis; maximal compromise at the level of the ligamentum flavum
  • Type I or Type II: Significant neurologic
    recovery occurred in >90%, regardless of the severity of the initial
    paralysis or treatment method.
  • Type III: Significant neurologic recovery occurred in <50%.
  • Type IV: The response was variable.
Camissa et al.
  • They associated dural tears in 37% of burst fractures with associated laminar fractures; all patients had neurologic deficits.
  • They concluded that the presence of a
    preoperative neurologic deficit in a patient who had a burst fracture
    and an associated laminar fracture was a sensitive (100%) and specific
    (74%) predictor of dural laceration, as well as a predictor of risk for
    associated entrapment of neural elements.
Keenen et al.
  • They reported an 8% incidence of dural tears in all surgically treated spine fractures, 25% in lumbar burst fractures.
  • In patients with burst fractures and a
    dural tear, 86% had neurologic deficits versus 42% in those with burst
    fractures without a dural tear.
COMPLICATIONS
Complications of spinal cord injury are covered in Chapter 8.

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