Lumbar Spine #s

 

Incidence and Distribution
Roentgenographic assessment
Tomography
Denis' three-column theory of spinal stability
Denis' classification of thoracolumbar spinal injuries
Radiographic Characteristics
Osteoporotic Compression
Pathologic Fracture of the Spine
Radiographic Characteristics lateral film
CT Scan
Radiographic Characteristics
Fracture Dislocations
Correlation of the classification w/ neurological deficits
Burst fractures
Correlation of the classification with instability and basic rationale for treatment
Instability of the first degree (mechanical instability)
Instability of the second degree (neurological instability)
Instability of 3rd degree (mechanical & neurologic)

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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

    • 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

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