Spine Injury: Thoracic

Basics

Description

  • The following forces account for most thoracic fractures and dislocations:
    • Axial compression
    • Flexion–rotation
    • Shear
    • Flexion–distraction
    • Extension
  • 3 anatomically distinct columns; if 2 of the 3 columns are disrupted, the spinal column is unstable:
    • Posterior column: Posterior bony arch and interconnecting ligamentous structures
    • Middle column: Posterior aspects of the vertebral bodies, posterior annulus fibrosis, and posterior longitudinal ligament
    • Anterior column: Anterior longitudinal ligament, anterior annulus fibrosis, and anterior vertebral body
  • Major vs minor fractures:
    • Minor:
      • Isolated articular fracture
      • Transverse process fracture
      • Spinous process fracture
      • Pars interarticularis fracture
    • Major:
      • Compression fracture
      • Burst fracture
      • Seat belt injury
      • Fracture–dislocation
  • Compression fracture (anterior or lateral flexion):
    • Fracture of anterior portion of vertebral body with intact middle column
    • May be posterior column disruption
    • Generally stable injuries
    • Type A: Fracture through both end plates
    • Type B: Fracture through superior end plate (more frequent pattern)
    • Type C: Fracture through inferior end plate
    • Type D: Both end plates intact
    • Unstable if >50% body compression
  • Burst fracture (axial loading):
    • Fracture through anterior and middle columns of spine
    • May have spreading of posterior elements and laminar fractures with possible retropulsion into the spinal canal and potential neurologic compromise
    • Type A: Fracture through both end plates
    • Type B: Fracture through superior end plate (50% of all burst fracture)
    • Type C: Fracture through inferior end plate
    • Type D: Burst in middle column with rotational injury leading to subluxation
    • Type E: Burst in middle column with asymmetric compression of anterior column
  • Seat belt injury (flexion–distraction):
    • Distraction of posterior and middle columns with or without a compression fracture of anterior column
    • Typically caused by lap belts used without shoulder harness
    • Up to 50% may have associated abdominal injuries
    • Type A: 1 level injury through bone
    • Type B: 1 level injury, primarily ligamentous
    • Type C: 2 level injury, disruption of bone through middle column
    • Type D: 2 level injury, disruption of middle column through ligaments and disc with no middle column fracture
    • Type B, C, and D considered unstable pattern
  • Fracture dislocations:
    • Failure of all 3 columns following compression, tension, rotation, or shear forces
    • Type A: Flexion–rotation; fall from height
    • Type B: Shear-violent force across long axis of trunk
    • Type C: Flexion–distraction; bilateral facet dislocation
    • Highly unstable injuries
    • More than 75% of cases with neurologic deficits

Etiology

  • Thoracic spine is rigid owing to the support of the rib cage and the costovertebral articulations:
    • The spinal canal is narrowest in the thoracic spine
  • Traumatic thoracic spine fractures require enormous forces. Motor vehicle and motorcycle collisions, pedestrian’s struck, and falls (particularly from height >10 ft) account for most fractures:
    • A small percentage are caused by penetrating injuries (see “Spinal Cord Syndromes”)
    • 50% of all spinal fractures and 40% of all spinal cord injuries occur at the thoracolumbar junction (T11–L2)

Pediatric Considerations

  • Suspect nonaccidental trauma if thoracic spine injury without clear history of motor vehicle trauma
  • Posterior rib fractures raise index of suspicion for abuse and require closer survey of thoracic spine and entire body for occult injury

Geriatric Considerations

Increased brittleness of bones in elderly (>65 yr) predispose to fractures with less severe mechanism, falls from lesser height

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