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Information

 Skull and Spine Disorders

◊40% of all vertebral fractures that cause neurologic deficit; mostly complex (body + posterior elements involved)

Location:⅔ at thoracolumbar junction

Morphology:

  1. Compression
    = loss of vertebral body height / disruption of vertebral endplate
    • vertebral height loss (approximate percentage!)
    • degree of kyphosis
  2. Burst
    = compression of posterior vertebral body + varying degrees of retropulsion
    • “burst” fragments at superior surface of body
    • retropulsion of body fragments into spinal canal:
      • = distance of line drawn between posterior margins of adjacent vertebral bodies + most posterior margin of bone fragment
    • narrowing of spinal canal (approximate percentage!)
  3. Translation / rotation
    = horizontal displacement or rotation of one vertebral body with respect to another
    • rotation of spinous processes
    • uni- / bilateral facet fracture-dislocation
    • vertebral subluxation
  4. Distraction
    = dissociation along vertical axis ← disruption of anterior and posterior ligaments + osseous elements
    • diastasis of apophyseal joints:
    • widening of facet joints
    • empty “naked” facet joints
    • perched / dislocated facet joints
    • widening of interspinous space
    • avulsion fracture of superior / inferior aspects of contiguous spinous processes
    • vertebral body translation / rotation

    Cx: kyphotic progression → subsequent vertebral collapse

Injury of Posterior Ligament Complex

MRI (only modality for direct assessment!):

CT:

Fracture of Upper Thoracic Spine (T1 to T10)  !!navigator!!

Frequency: in 3% of all blunt chest trauma

Types:

  1. Compression / axial loading fracture (most common)
    • wedging of vertebral body
    • retropulsion of bone fragments
    • posttraumatic disk herniation

  2. Burst fracture (more severe compression fracture)
    • associated fracture of posterior neural arch
    • comminuted retropulsed bone fragments
  3. Sagittal slice fracture
    • vertebra above telescopes into vertebra below, displacing it laterally
  4. Anterior / posterior dislocation
    • torn anterior / posterior longitudinal ligament
    • facet dislocation
  • Relatively stable fractures due to rib cage + strong costovertebral ligaments + more horizontal orientation of facet joints!
  • Only 51% detected on initial CXR!

Often associated with: fracture of sternum

  • widening of paraspinal lines
  • mediastinal widening
  • loss of height of vertebral body
  • obscuration of pedicle
  • left apical cap
  • deviation of nasogastric tube

Signs of Spinal Instability:

= inability to maintain normal associations between vertebral segments while under physiologic load

  • displaced vertebra
  • widening of interspinous / interlaminar distance
  • facet dislocation
  • disruption of posterior vertebral body line

Fracture of Thoracolumbar Junction (T11 to L2)  !!navigator!!

= area of transition between a stiff + mobile segment of spine

  • neurologic deficit (in up to 40%)

Classification based on injury to the middle column:

  1. Hyperflexion injury (most common)
    = compression of anterior column + distraction of posterior spinal elements
    1. hyperflexion-compression fracture
      • loss of height of vertebral body anteriorly + laterally
      • focal kyphosis / scoliosis
      • fracture of anterosuperior endplate
    2. flexion-rotation injury (unusual)
      • Very unstable!
      • catastrophic neurologic sequelae: paraplegia
      • subluxation / dislocation
      • widening of interspinous distance
      • fractures of lamina, transverse process, facets, adjacent ribs
    3. shearing fracture-dislocation
      = damage of all 3 columns ← horizontally impacting force
    4. flexion-distraction injury: Chance fracture
  2. Hyperextension injury (extremely uncommon)
    • widened disk space anteriorly
    • posterior subluxation
    • vertebral anterior superior corner avulsion
    • posterior arch fracture
  3. Axial compression fracture
    • Unstable!
    • burst fracture with herniation of intervertebral disk through endplates + comminution of vertebral body
    • marked anterior vertebral body wedging
    • retropulsed bone fragment
    • increase in interpediculate distance
    • ± vertical fracture through vertebral body, pedicle, lamina

Chance Fracture  !!navigator!!

= SEATBELT FRACTURE

[George Quentin Chance, British radiologist in Manchester, England]

Mechanism: shearing flexion-distraction injury (lap-type seatbelt injury in back-seat passengers)

  • neurologic deficit infrequent (20%)

Location: L2 or L3

  • horizontal splitting of spinous process, pedicles, laminae + superior portion of vertebral body
  • disruption of ligaments
  • distraction of intervertebral disk + facet joints
  • Fracture often unstable!

Often associated with:

  1. other bone injury
    rib fractures along the course of diagonal strap; sternal fractures; clavicular fractures
  2. soft-tissue injury
    transverse tear of rectus abdominis muscle; anterior peritoneal tear; diaphragmatic rupture
  3. vascular injury
    mesenteric vascular tear; transection of common carotid artery; injury to internal carotid artery, subclavian artery, superior vena cava; thoracic aortic tear; abdominal aortic transection
  4. visceral injury
    perforation of jejunum + ileum >large intestine >duodenum (free intraperitoneal fluid in 100%, mesenteric infiltration in 88%, thickened bowel wall in 75%, extraluminal air in 56%); laceration / rupture of liver, spleen, kidneys, pancreas, distended urinary bladder; uterine injury

Chance Equivalent

= purely ligamentous disruption leading to lumbar subluxation / dislocation

  • mild widening of posterior aspect of affected disk space
  • widened facet joints
  • splaying of spinous processes = “empty hole” sign on AP view

Holdsworth Fracture  !!navigator!!

[Sir Frank Wild Holdsworth (1904–1969), British pioneering orthopedist in rehabilitation of spinal injuries]

Location: thoracolumbar junction

  • unstable spinal column fracture-dislocation with fracture through vertebral body + articular processes
  • rupture of posterior spinal ligaments

Seatbelt Injury  !!navigator!!

= injury caused by three-point restraint type (combined lap and shoulder belt device)

  • bruise in subcutaneous tissue + fat of anterior chest wall
  • skin abrasions are associated with significant internal injuries (in 30%)
    • Skeleton
      sternum, ribs (along diagonal course of shoulder harness), clavicle, transverse processes of C7 or T1
    • Cardiovascular
      aortic transection, cardiac contusion, ventricular rupture, subclavian artery, SVC
    • Airways
      tracheal / laryngeal tear, diaphragmatic rupture

Transverse Process Fracture of Lumbar Spine  !!navigator!!

Cause: direct trauma, violent lateral flexion-extension forces, avulsion of psoas muscle, Malgaigne fracture

Frequency: 7%

In 21–51% associated injury:

  • genitourinary injury, hepatic + splenic laceration

Location: L3 >L2 >L1 >L4 >L5; L÷R = 2÷1; multiple÷single = 2÷1; unilateral÷bilateral = 20÷1

  • vertical÷horizontal (94%÷6%) fractures
  • associated lumbar burst / compression fracture
  • Detection by conventional radiography in 40% only!

Prognosis: minor and stable injury; 10% mortality

Sacral Fracture  !!navigator!!

  • Zone 1 = fracture lateral to sacral foramina
    • significant neurologic deficit (uncommon)
  • Zone 2 = fracture through ≥1 foramina
    • unilateral lumbar / sacral radiculopathy (rare)
  • Zone 3 = fracture through central canal
    • significant bilateral neurologic damage (frequent): bowel / bladder incontinence

Cx: chronic disability (in up to 50%)

Acute Atraumatic Compression Fractures of Spine  !!navigator!!

Osteoporotic Compression Fracture of Vertebra

  • low-signal-intensity band on T1WI and T2WI (93% sensitive)
  • spared normal bone marrow SI of the vertebral body (85% sensitive)
  • retropulsion of a posterior bone fragment into spinal canal (60% sensitive)
  • “fluid” sign = circumscribed fluidlike SI on T2WI + STIR subjacent to fractured end plate
  • multiple compression fractures
  • rimlike enhancement around low-signal-intensity bands
  • “wafer-like” distribution of radionuclide activity along endplate

Metastatic Compression Fracture of Vertebra

  • convex posterior border of vertebral body (74% sensitive)
  • abnormal SI of the pedicle or posterior element on enhanced fat-suppressed T1WI
  • epidural mass
  • encasing epidural mass
  • focal paraspinal soft-tissue mass (41% sensitive)
  • other sites of spinal metastases without compression fractures (63% sensitive)
  • enhancement of metastatic foci
  • completely replaced bone marrow of vertebral body (by tumor cells before trabeculae critically weakened)

Cx: spinal cord compression

 Outline