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
  • Type A: Fracture through both end plates
  • Type B: Fracture through superior end plate
  • Type C: Fracture through inferior end plate
  • Type D: Both end plates intact
• Burst fracture (axial loading):
  • Fracture through middle column 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
  • 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 anterior column intact
  • Typically caused by lap belts used without shoulder harness
  • Type A: Through bone
  • Type B: Primarily ligamentous
  • Type C: Disruption of bone through middle column
  • Type D: Through ligaments and disc with no middle column fracture
• 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

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)

• 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