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British Medical Books Health Issues Computerized Tomography

Incidence and Distribution

  • two-thirds at T12, L1, and L2
  • 90% between T11 & L4
  • in children at T4, T5, & L2
  • adjacent vertebrae
  • 20% associated injuries
    • calcaneus #
    • sternum #

Patient evaluation

  • backboard
  • collar or sand bags
  • resuscitation ( ATLS 1992 )
    • ABC
    • hypotension w/ bradycardia
    • high dose methylprednisolone ( Bracken,1990 N Eng J Med )
  • inspection & palpation
    • localised tenderness, gaps, swelling, and gibbous
    • occult fractures in more than 30%
  • neurologic examination
    • muscle strength
    • sensory examination
    • reflexes
    • signs of sacral sparing
    • Frankel classification A - E

Roentgenographic assessment

Plain film

AP & lateral views

    • junctional areas
    • coned-down view
    • complete spine series
      • non-contigous spine fractures occur in 10-30%
    • soft tissues - paraspinous mass
      • thoracic spine
      • haematomas
    • alignement - dislocation
    • loss of height
    • status of the anterior, middle & posterior elements
    • interpedicular & inter-spinous process distance

Computed Tomography

  • more than a simple wedge compression #
  • in older patients
    • osteoporotic compression or pathologic #
  • wedge compression <---> burst fractures
    • status of the posterior wall of the vertebral body
    • fragments in relation to the spinal canal
  • disadvantage
    • if #-s in the horizontal plane
    • three-dimensional reconstruction
    • tomography
    • scoliosis, kyphosis → pseudo fractures
    • water-soluble contrast

Tomography

  • axially oriented fractures of the posterior elements
  • demonstrate alignment

MRI

  • cord pathology
    • contusion
    • transsection
  • other soft-tissue injuries & disk

indicated

    • progressive neurologic deterioration
    • incongruous neurologic and skeletal injury
    • unexplained neurologic deficit
    • also to assess the status of the posterior ligamentous complex

Myelography

  • little role

Classification

  • majority simple wedge compression fractures
  • based on
    • radiographic appearance
    • forces presumed to have created the injury

Denis' three-column theory of spinal stability

  • anterior column
  • middle column
  • posterior column
  • involvement > 2 columns - instability
  • Thoraco Lumbar Spine

  • third or middle column as a hinge or fulcrum

  • middle column remains intact stable injury

Denis's classification of thoracolumbar spinal injuries

  • retrospective study of 412 thoracolumbar #-s
  • divided into minor & major injuries

Minor spinal injuries

  • Articular process fracture : 3 (0.7%)
  • Transverse process fracture : 56 (13.59%)
  • Spinous process fracture : 7 (1.69%)
  • Pars interarticularis fracture : 4 (0.97%)

Major spinal injuries

  • Compression fractures : 197 (47.81%)
  • Burst fractures : 59 (14.32%)
  • Fracture dislocations : 67 (16.26%)
  • Seat-belt type spinal injuries : 19 ( 4.61%)
  • minor injuries ---> all stable
  • four basic mechanisms of injury:
    • compression
    • distraction
    • rotation and
    • shear

Compression Fractures

  • failure of the anterior column under compression forces
    • middle column intact & acts as a hinge
    • partial tension failure of the posterior column
  • anterior & lateral

Radiographic Characteristics

  • lateral film:
    • decreased height of the anterior vertebral body
    • posterior height unchanged, posterior cortex intact
    • no subluxation
    • interspinous distance increased

AP film

  • buckling of the lateral vertebral cortex
  • lateral wedging

Characteristics on CT Scan

  • vertebral ring (posterior wall, pedicles & lamina) intact
  • rupture of the anterior end-plate

  • Thoraco Lumbar Spine

Osteoporotic Compression

    • in older individuals associated with osteoporosis
    • more common & earlier in females ( postmenopausal ) than in males
    • whites » blacks
    • peak incidence in mid-dorsal spine & thoracolumbar junction ---> classic kyphotic deformity (dowager's hump)
  • distinguish between compression of a vertebra d/t OP & that d/t acute trauma
  • acute trauma
  • evidence of cortical disruption
  • increase in density beneath the endplate of an involved vertebra indicate impaction of bone due to acute fracture
  • osteoporotic compression
    • the deformed vertebral body similar in density to adjacent vertebrae
    • frequently show evidence of osteophytic spurs
  • radioisotopic bone scan of little use
  • CT scan may be useful

Pathologic Fracture of the Spine

  • metastatic disease

radiographic feature

  • bony destruction - pedicle erosion
  • any component of the vertebra
  • the fractures are multiple, discontiguous, or both
  • surrounding soft tissue mass

history

  • trivial trauma
    • fracture of osteoporosis or with metastatic disease
  • CT or MRI examination helps

Burst Fractures

  • axial load
    • failure of the anterior & middle columns
  • neurological deficit

Radiographic Characteristics
lateral film

  • failure of the middle column
    • fracture of the posterior wall cortex
    • loss of posterior height
    • retropulsion of a fragment of bone into the canal

AP film

  • increase of the interpediculate distance
  • vertical laminar fracture
  • splaying of the posterior joints

CT Scan

  • break of the posterior wall of the vertebral body
  • retropulsion of bone into the canal
  • five different types of burst fractures
    • Type A - E

Seat-Belt-Type Injuries

  • failure of both the posterior and middle columns
    • tension forces by flexion and distraction
    • anterior column acts as a hinge

Radiographic Characteristics

    • increase of interspinous distance
    • horizontal split of the transverse processes, pedicles
    • pars interarticularis fractures
    • increased height of the posterior vertebral body & posterior opening of the disc space

CT Scan

    • not much information
    • may totally miss the fracture - lateral tomograms
  • subtypes

one-level lesions

  • Chance fracture
  • ligamentous disruption

two-level lesions

Fracture Dislocations

  • failure of all columns under compression, tension, rotation or shear
  • this leads to subluxation or dislocation
    • may present in a reduced position - high index of suspicion
    • subtle signs (multiple rib #, multiple transverse process #, horizontal laminar or spinous process #s)
  • Types and Subtypes
    • type A - flexion rotation
    • type B - shear type
    • type C - fracture dislocation

Correlation of the classification with neurological deficits

  • close link between mechanism of injury, type of # & neurological deficit
  • Isolated transverse process fractures
    • T1 and T2 ---> brachial plexus injuries
    • L4 and LS ---> pelvic fractures with lumbosacral plexus injuries
    Isolated spinous process fractures
    • temporary conus contusions
  • Isolated facet and pars interarticularis fractures
  • Compression fractures
  • Seat-Belt Type Injuries
    • no neurological injury

Burst fractures

  • 50% were neurologically intact at first examination
    • Hx leg numbness, tingling and/or weakness
    • impact to conus or cauda equina
  • 50% with neurological deficits
    • high proportion of incomplete paraplegia (96.45%)
  • Fracture dislocations
  • Flexion rotation type
    • neurologically intact in 25%
    • when neurologically injured, 50% of them were complete
  • Shear type
    • all cases were complete paraplegics on admission (Frankel A)
  • Flexion-distraction type
    • were incomplete paraplegics in 75% cases
    • intact in one case 25%

Correlation of the classification with instability and basic rationale for treatment

Stable injury

  • minimal & moderate compression #s w/ an intact posterior column

Rx

  • early ambulation w/ or w/out external immobilisation
    • degree of compression
    • kyphosis & the age of the patient

Instability of the first degree (mechanical instability)

  • clinical instability
  • "the loss of the ability of the spine under physiologic loads to maintain relationships between vertebrae in such a way that there is neither damage no subsequent irritation to the spinal cord or nerve roots and, in addition, no development of deformity with excessive pain"( Panjabi )
  • severe compression fractures and seat-belt-type injuries
    • disruption of the posterior ligamentous
    • flexion allows buckling around the hinge of the anterior column
  • does not acutely threaten the neural elements

Rx

  • bedrest in hyperextension
  • brace
  • ORIF

Instability of the second degree (neurological instability)

  • burst fractures
    • middle column ruptured under axial load
    • continued compression by the fragment of the middle column against the neural elements
    • early ambulation leads to axial load
    • may develop neurology if treated conservatively

Rx

  • controversial

non-operative

  • neurologically intact
  • angle of kyphosis < 15°
  • angle of scoliosis < 15°
  • displacement in any direction < 5 mm

surgical

  • if > any of above
  • pt. should be informed of the neurological risk
  • posterolateral instrumentation & fusion
  • anterior or posterior decompression

Instability of 3rd degree (mechanical & neurologic)

  • fracture-dislocation & severe burst fracture w/ neurological deficit
  • 2°displacements & progression of neurological deficit may occur

Rx

  • prevention of both complications
  • surgical decompression and stabilisation