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  • SUMMARY
    • Thoracolumbar Burst Fractures are a common high-energy traumatic vertebral fractures caused by flexion of the spine that leads to a compression force through the anterior and middle column of the vertebrae leading to retropulsion of bone into the spinal canal and compression of the neural elements.
    • Diagnosis is made with radiographs of the thoracolumbar spine. CT scan is useful for fracture characterization and surgical planning. 
    • Treatment is bracing or surgical decompression and stabilization depending on whether the patient has neurologic deficits and whether the facture is unstable with a risk of drifting into kyphosis.
  • Epidemiology
    • Demographics
      • often seen from falls from height or motor cycle accidents
  •   ETIOLOGY
    • Pathophysiology
      • mechanism
        • axial loading with flexion
      • pathoanatomy
        • at thoracolumbar junction there is fulcrum of increased motion that makes spine more vulnerable to traumatic injury
          • burst fractures typically occur between T10-L2 (thoracolumbar junction)
        • neurologic deficits
          • canal compromise often caused by retropulsion of bone
            • maximum canal occlusion and neural compression at moment of impact
            • tissue recoiling post-injury can minimize the extent of displacement
            • retropulsed fragments resorb over time and usually do not cause progressive neurologic deterioration
          • deficit type
            • location of stenosis relative to conus determines
              • spinal cord injury
              • conus medullaris syndrome
              • neurogenic claudication due to stenosis distal to conus
    • Associated injuries
      • concomitant spine fractures
        • occurs in 20%
      • traumatic durotomy
        • associated with 
          • lamina fractures
          • split spinous process
      • chest and intra-abdominal injuries
        • common
        • thoracic spine fractures with neurologic deficit
          • 1/3 associated with hemopneumothorax, major vessel injury, and diaphragmatic rupture
        • flexion-distration and fracture-dislocations
          • bowel rupture, major vessel injury, upper urinary tract injury, hepatic, splenic, and pancreatic lacerations
      • long bone fractures
        • can make rehabilitation difficult
  • ANATOMY
    • Thoracic osteology
      • T1-10 are rigidly fixed to ribs that join each other anteriorly via the sternum
        • least mobile portion of the entire spine
      • T10-L2 is considered the thoracolumbar junction
        • T10-12 have free floating ribs and are more mobile than the upper thoracic spine
        • transition from rigid thoracic spine to mobile lumbar spine acts as a stress riser and predisposes to injury
    • Lumbar osteology
      • increasingly more mobile as progresses caudal
      • increasingly prone to degenerative changes
    • Denis three column system
      • clinical relevance
        • only moderately reliable in determining clinical degree of stability
      • definitions
        • anterior column
          • anterior longitudinal ligament (ALL)
          • anterior 2/3 of vertebral body and annulus
        • middle column
          • posterior longitudinal ligament (PLL)
          • posterior 1/3 of vertebral body and annulus
        • posterior column
          • pedicles
          • lamina
          • facets
          • ligamentum flavum
          • spinous process
          • posterior ligament complex (PLC)
        • instability defined by
          • injury to middle column
            • as evidenced by widening of interpedicular distance on AP radiograph
            • loss of height of posterior cortex of vertebral body
          • disruption of posterior ligament complex combined with anterior and middle column involvement
    • Posterior Ligamentous Complex
      • considered to be a critical predictor of spinal fracture stability
      • consists of
        • supraspinous ligament
        • interspinous ligament
        • ligamentum flavum
        • facet capsule
      • evaluation
        • determining the integrity of the PLC can be challenging
          • conditions where PLC is clearly ruptured
            • bony chance fracture
            • widening of interspinous distance
            • progressive kyphosis with nonoperative treatment
            • facet diastasis
          • conditions where integrity of PLC is indeterminant
            • MRI shows signal intensity between spinous process
    • Spinal cord
      • spinal cord ends at L1-2
        • conus medullaris
          • houses upper motor neurons on the sacral motor nerves
        • fractures involving L1 and result in conus medullaris syndrome
          • paralysis of the bowel and bladder with sparring of the motor nerve roots of the lower extremity
  • CLASSIFICATION
    • Dennis classification
      • Type A
        • fracture of both end-plates. The bone is retropulsed into the canal.
      • Type B
        • fracture of the superior end-plate. It is common and occurs due to a combination of axial load with flexion.
      • Type C
        • fracture of the inferior end-plate.
      • Type D
        • Burst rotation. This fracture could be misdiagnosed as a fracture-dislocation. The mechanism of this injury is a combination of axial load and rotation.
      • Type E
        • Burst lateral flexion. This type of fracture differs from the lateral compression fracture in that it presents an increase of the interpediculate distance on anteroposterior roentgenogram
    • Thoracolumbar Injury Classification and Severity Score
      • injury characteristic qualifier points
        • injury morphology
          • compression (+1 point)
          • burst (+2 points)
          • rotation/translation (+3 points)
          • distraction (+4 points)
        • neurologic status
          • intact (0 point)
          • nerve root (+2 points)
          • incomplete Spinal cord or conus medullaris injury (+3 points)
          • complete Spinal cord or conus medullaris injury (+2 points)
          • cauda equina syndrome (+3 points)
        • posterior ligamentous complex integrity
          • intact (0 point)
            • no interspinous ligament widening seen with flexion views. MRI shows no edema in interspinous ligament region
          • suspected/indeterminate (+2 points)
            • MRI shows some signal in region of interspinous ligaments
          • disrupted (+3 points)
            • widening of interspinous distance seen
      • TLICS treatment implications
        • score < 4 points
          • nonsurgical management
        • score = 4 points
          • nonsurgical or surgical managment
        • score > 4 points
          • surgical management indicated
  • PRESENTATION
    • History
      • high-energy mechanism
        • axial-loading and flexion mechanisms
          • fall from height (e.g. fall from deer hunting stand, fall from ladder, etc.)
          • high-speed motor vehicle collision
    • Symptoms
      • severe back pain
      • radicular pain
      • parasthesias
    • Physical exam
      • vital signs
        • hypotension is common
          • neurogenic shock
            • hypotension with associated bradycardia
              • suggests spinal cord injury leading to loss of autonomic regulation
          • hypovolemic shock
            • hypotension with compensatory tachycardia
              • suggests massive hemorrhage from major vessel injury
      • inspection
        • log roll patient during initial assessment to avoid iatrogenic spinal cord injury in the setting of an unstable fracture pattern
        • skin abraisons and ecchymosis
          • open spinal fractures are uncommon
      • palpation of spinous processes
        • fluid collection
        • crepitus
        • increased interspinous distance
          • suggests injury to the posterior elements
        • localized tenderness
      • neurologic examination
        • motor
        • sensory
        • reflexes
          • absence of bulbocavernous reflex is considered spinal shock
            • can persist for up to 72 hours
            • hyperactive bulbocavernous reflex suggests disinhibition and a complete spinal cord injury
  • IMAGING
    • Radiographs
      • recommended views
        • AP/lateral cervical, thoracic, lumbar spine
          • often CT chest, abdomen, and pelvis done by trauma team and instead of radiographs
          • imaging of entire spine must be performed due to concomitant spine fractures in 20%
        • flexion and extension lateral radiographs
          • useful once patient is stabilized to get understanding of integrity of PLC
        • findings
          • AP shows
            • widening of pedicles
            • coronal deformity
          • lateral shows
            • retropulsion of bone into canal
            • extent of retropulsion can be underestimated with plain radiographs alone
            • kyphotic deformity
            • chance-like spinous process fx
          • flexion/extension
            • diastasis of spinous process with flexion indicates soft tissue injury to PLC
    • CT scan
      • indications
        • fracture on plain film
        • neurologic deficit in lower extremity
        • inadequate plain films
          • higher sensitivity at detecting acute spine fractures than plain films
      • most accurately assesses the extent of fragment retropulsion
        • best assess on the axial views
      • better assessment vertebral body comminution
    • CT myelography
      • indications
        • alternative for patients with pacemaker and other implants that are MRI incompatible
        • cannot assess the cord status
        • consider traumatic durotomy
    • MRI
      • indications
        • whenever neurological deficits
        • assess the presence of a posterior ligamentous injury
          • should be performed in nearly every case, unless radiographs and CT clearly suggest injury
      • useful to evaluate for
        • level of conus relative to retropulsed bone
        • spinal cord or thecal sac compression by disk or osseous material
        • cord edema or hematoma
          • cord edema
            • fusiform cord enlargement
            • increased signal intensity on T2-weighted images
          • cord hematoma
            • decreased singal intensity on T2-weighted images
            • halo of T2 enhancement for surrounding edema
          • presence of cord edema more than 2 vertebral levels and hematoma are poor prognostic signs for functional motor recovery
        • injury posterior ligament complex
          • increased signal intensity on T2 weighted images in PLC is concerning for instability and may warrant surgical intervention
          • best visualized on the sagittal images
  • TREATMENT
    • Nonoperative
      • activity as tolerated +/- thoracolumbosacral orthosis
        • indications
          • patients that are neurologically intact and mechanically stable
            • posterior ligament complex preserved
            • no focal kyphosis on flexion and extension lateral radiographs
            • kyphosis < 30° (controversial)
            • vertebral body has lost < 50% of body height (controversial)
          • TLICS score = 3 or lower
        • modality
          • thoracolumbar orthosis
            • recent evidence shows no clear advantage of TLSO on outcomes
              • if it provides symptomatic relief, may be beneficial for patient
              • bracing may not be suitable for those with associated abdominal or chest injuries
        • outcomes
          • retropulsed fragments resorb over time and usually do not cause neurologic deterioration
          • decreased complication rates in neurologically intact patients treated nonsurgically
          • equivalent outcomes in neurologically intact patients
          • prolonged bedrest associated with increased deconditioning and recumbency complications (pneumonia, DVT, etc.)
    • Operative
      • posterior instrumented fusion/stabilization without decompression
        • indications
          • unstable fracture pattern as defined by
            • injury to the Posterior Ligament Complex (PLC)
            • progressive kyphosis
            • lamina fractures (controversial)
            • polytrauma
              • surgical stabilization can assist with recovery and rehabilitation of other injuries
        • technique
          • may be performed with percutanous pedicle screws using fluoroscopy or navigation
          • may extend instrumentation further than level of arthrodesis (fuse short, instrument long)
        • outcomes
          • unstable injuries are more likely to benefit from surgical stabilization compared to nonsurgical treatment
      • neurologic decompression & spinal stabilization
        • indications
          • neurologic deficits with radiographic evidence of cord/thecal sac compression
            • both complete and incomplete spinal cord injuries require decompression and stabilization to facilitate rehabilitation
          • TLICS score = 5 or higher
        • techniques
          • while classic teaching was anterior approach is required to eliminate anterior pathology, with modern techniques decompression can be performed with
            • posterior approach
              • favored when
                • below conus so possible to medialize thecal sac to perform decompression of canal / posterior corpectomy and expandable cage
                • injury to posterior ligamentous complex so posterior tension-band stabilization required
                • fracture dislocations
            • anterior/direct lateral approach
              • favored when
                • neurologic deficits caused by anterior compression (bony retropulsion) , especially above the conus medullaris (above L2)
                • allow for thorough decompression of the thecal sac
                • substantial vertebral body comminution in order to reconstitute the anterior column
                • kyphotic deformity >30°
                • chronic injuries
                  • greater than 4-5 days from the injury
              • cons
                • must consider level of diaphragm
        • outcomes
          • studies have suggested posterior distraction instrumentation with ligamentotaxis have similar clinical and radiographic outcomes as anterior decompression and 360° stabilization
          • over distraction of the anterior column can lead to pseudoarthrosis, chronic pain, and recurrent deformity
  • TECHNIQUES
    • Posterior instrumented fusion/stabilization without decompression
      • approach
        • posterior midline approach
          • subperiosteal elevation of paraspinal musculature
          • expose lateral to the transverse processes
      • technique
        • transpedicular screw fixation above and below the level of injury
          • historically involve three levels above and two levels below the level of injury
            • modern constructs typically involve one level above and one level below the injury
              • short segment fixation not suitable for injuires involving the thoracolumbar junction
      • complications
        • loss of sagittal plane correction
    • Neurologic decompression & spine stabilization
      • approach
        • posterior approach
          • typically posterior midline approach
            • subperiosteal elevation of paraspinal musculature
            • expose lateral to the transverse processes
        • anterior approach
          • lumbar spine
            • anterior retroperitoneal or transperitoneal approach
              • left paramedian incision
            • suitable for levels below L1
          • thoracolumbar junction
            • lateral lumbotomy
            • suitable for injuries at T11-L1
            • left-sided approach to avoid liver obstructing access
          • thoracic spine
            • lateral thoracotomy
              • right-sided approach to avoid major vessels
              • appropriate for injuries above T11
      • technique
        • neural decompression
          • direct decompression
            • posterior decompression
              • retropulsed bone can be removed via transpedicular approach
                • usually done below the level of the conus medullaris (L2)
                • significant dural retraction required, which may iatrogenically damage the cord
                • avoid laminectomy if possible as it will further destabilize the spine by compromising the posterior supporting structures
            • anterior decompression
              • corpectomy performed with direct removal of canal-occupying fragments
                • ipsilateral pedicle and transverse process are removed
                • corpectomy performed until the medial wall of the contralateral pedicle is visualized
              • preferrable for fractures at or above the level of the conus medullaris (L1-2)
          • indirect decompression
            • distraction and lordosing rod construct leads to ligamentotaxis of the retropulsed fragments
              • attachements of the annulus fibrosis and posterior longitudinal ligament to the fragments facilitates reduction
              • less effective if performed 4-5 days after the injury
            • restored height and sagittal alignment with posterior instrumentation
            • monoaxial screws provided greater distractive forces for deformity correction
        • arthrodesis
          • posterior fusion
            • usually performed with locally harvested autograft and freeze-dried cancellous allograft +/- BMP
            • posterior instrumentation should be under distraction and lordosis to restore vertebral body height and achieve indirect decompression
          • anterior fusion
            • structural bone graft placed in corpectomy site to reconstitute the anterior column
              • tricortical iliac crest autograft
              • humeral or tibial allograft
              • expandable metal cages with locally harvested autograft
            • can be stabilized with anterior instrumentation, posterior instrumentation, or both
      • complications
        • posterior decompression
          • dural tear
          • iatrogenic cord injury
            • excessive thecal retraction above the conus medullaris
          • iatrogenic instability
            • laminectomy in the setting of disrupted posterior ligamentous complex
        • anterior decompression
          • ileus
            • transperitoneal approach to the lumbar spine
          • pleural effusion
            • related to approaches requiring thoractomy
  • COMPLICATIONS
    • Entrapped nerve roots and dural tear
      • from associated lamina fractures
      • can be iatrogenic from decompression
        • decreased risk of dural tears with anterior approach due to improved visualization of the thecal sac during decompression
      • requires closure primarily or reinforced with dural patch
        • prolonged recumbency postoperatively
    • Pain
      • most common
      • over distraction with instrumentation
    • Progressive kyphosis
      • common with unrecognized injury to PLL
      • increased comminution of the vertebral body
        • loss of anterior column support
    • Flat back
      • leads to pain, a forward flexed posture, and easy fatigue
      • post-traumatic syringomyelia
    • Surgical site infection
      • can occur in up to 10% of cases
        • trauma predisposes to infection
          • catabolic state
          • increased soft tissue damage
          • inflammatory response
      • requires irrigation and debridement with culture specific antibiotics
    • Pseudoarthrosis
      • can result from overdistraction instrumentation
    • Iatrogenic neurologic injury
      • can occur in 1% of cases
      • causes include
        • over medialized pedicle screws
        • inadvertant manipulation of the spinal cord
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