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3: Neurosurgery > Chapter 34 Vertebral Fractures, Luxations and Subluxations > Flashcards

Chapter 34 Vertebral Fractures, Luxations and Subluxations Flashcards

1
Q

What is reported prevalence of vertebral column fractures/luxation/subluxations in dogs treated for severe blunt trauma?

A

10%

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2
Q

List the 5 types of primary SC injury

A
  1. Concussion
  2. Compression
  3. Shearing
  4. Laceration
  5. Elongation
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3
Q

In dos/cats with vertebral column fractures/luxation/subluxations, what % of cases have concurrent:

  • Abdominal trauma
  • Multiple vertebral column fractures/luxation/subluxations
  • Thoracic trauma
  • Concurrent fractures
A
  • Abdominal trauma approx 10%
  • Multiple vertebral column fractures/luxation/subluxations approx 20%
  • Thoracic trauma approx 30%
  • Concurrent fractures approx 40%
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4
Q

What is the most important prognostic factor for recovery following Sc injury?

A

Presence of nociception

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5
Q

What is the prognosis for functional recovery in dogs with absent nociception + IVDH vs with vertebral column fractures/luxation/subluxations

What is the prognosis for functional recovery in dogs with present nociception + vertebral column fractures/luxation/subluxations

A

IVDH 47 - 70% chance of recovery

Vertebral column fractures/luxation/subluxations 5 - 12% chance of recovery

If nociception present in vertebral column fractures/luxation/subluxations 80 - 90% chance of recovery

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6
Q

What is the sensitivity and specificity of radiography for diagnosis of vertebral column fractures?

And subluxations

A

Sensitivity fractures 72%

Sensitivity subluxations 77%

Particularly poor for detecting injury to dorsal and middle compartment

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7
Q

Describe the three compartment model of vertebral fractures.

What anatomical structures make up each compartment

A
  • Dorsal: Spinous process, vertebral lamina, articular processes, vertebral pedicles, dorsal ligamentous complex (supraspinous ligament, interspinous ligament, joint capsule of zygapophyseal joint, ligamentum flavum)
  • Middle: DLL, dorsal annulous fibrosus, dorsal portion of vertebral body
  • Ventral: remaonder of vertebral pody, lateral and ventral annulous fibosus, nucleus pulposus, VLL

Transverse computed tomographic images in a bone window of the midbody of a lumbar vertebra (A) and intervertebral space (B). The dotted lines represent the demarcation of the three-compartment model of the structures that contribute to the vertebral column stability.

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8
Q

What are the three anatomic structures (the principal contributors of vertebral column stability) used in the simpler vertebral fracture classification scheme

A
  • Zygapophyseal joints
  • IV disc
  • Vertebral body
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9
Q

What anatomical structure is the principal anatomic contributor to rotational stability of the vertebral column?

A

Intervertebral disc

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10
Q

How do isolated vertebral body fractures compare to isolated zygapophyseal joint fracture (even if bilateral)

A

Vertebral body fracture = very unstable

Zygapophyseal joint fracture can be relatively stable

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11
Q

Based on 3 compartment model and anatomic classification scheme, when is a fracture considered unstable?

A

If ≥ 2 compartments/structures compromised

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12
Q

What are the three goals of surgery for vertebral fracture/luxation/subluxation

A

Realignment

Stabilization

Decompression

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13
Q

What 3 owner expectations have to be met if pursuing sx in paralysed/nociception -ve cases?

A
  • Surgery is for provision of pain releif
  • Permanent paralysis
  • Permanent incontinence
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14
Q

What % of peripherally located axons are necessary for restoration of walking?

A

5-10%!

i.e. not very much. Secondary injury may contribute up to 10% of Sc damage i.e. significant is this is the difference between walking vs not walking)

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15
Q

How does reperfusion injury result in Sc injury?

A

Reperfusion –> release of oxygen-derived free radicals –> lipid peroxidation of neuronal and gial cell membranes

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16
Q

List 5 indications for surgical intervention in vertebral fractures/luxationssubluxation

A
  • Neuro defecits (with intact nociception)
  • Worsening neuro status
  • Intractable pain
  • Unstable
  • Sc compression
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17
Q

HOw can correct fracture/luxation reduction be assessed?

A

Check zygapophyseal joints

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18
Q

Label the diagram

A
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19
Q

What is the relationship between pin bending strength and radius

A

proportional to radius4

(area moment of inertia)

20
Q

What pin + pmma construct has been shown to be as intact vertebral column ex vivo

A

four pins + pmma (i.e. one pin on each side of vertebra)

21
Q

What are recommended pin entry points in thoracic vertebrae?

And lumbar vertebrae?

A

Thoracic vertebrae: At level of accessory process or tubercle of rib

Lumbar vertebrae: Between base of transverse process and accessory process.

To maximize bone-pin contact, the pin is directed in a lateral to medial, dorsal to ventral direction. For the pin to be placed in the vertebra cranial to the affected articulation, the pin is directed cranially, while in the vertebra caudal to the articulation, the pin is directed caudally. This trajectory results in seating of pins within the vertebra closer to the end plates, where the vertebral body is widest

22
Q

What are recommended pin insertion angles (from vertical) in thoracic and lumbar vertebrae?

And from ventral approach in cervical vertebral column

A

Thoracolumbar: In summary 30 - 60º

Cervical: 34 - 38º (can be increased in C7 as no transverse foramen to avoid)

23
Q

What structures can be damaged by pins placed through transcortex of vertebral bodies?

A

Azygous vein, aorta, pleura, lung.

24
Q

If excessive bleeding is encountered during vertebral body pin placement, which 2 structures might have been damaged?

A

Vertebral venous plexus or basivertebral vein

Cross-sections of L6 vertebra (A) and L4 vertebra (B) illustrating the basivertebral vein (arrow), which anastomoses with the internal vertebral venous plexus (arrowheads).

25
Q

What is the sensitivity of radiography for vertebral canal penetration of implants?

A

50%

26
Q

What are 2 manufacturer recommendations when using SOP plate for vertebral fracture/luxation

A
  • Bilateral application
  • At least 3 screws (total) per vertebra
27
Q

HOw does bending strenght of 3.5mm SOP compare with 3.5 mm LCP

A

SOP stronger

28
Q

How does unilateral 4 screw LCP comapre with 4 screw pin + PMMA construct?

A

Weaker

(but both stronger than intact vertebral column)

29
Q

List 6 possible techniques for management of TL vertebral fracture/luxation

A
  1. Pins + PMMA
  2. ESF
  3. Locking plates
  4. Auburn spinal plate (metal, fixation through spinous processes)
  5. Lubra plates (plastic, fixation between spinous processes)
  6. Spinal stapling (pins/wire wrapped around severl DSPs, secured to DSPs with wire through drill holes in DSP)
30
Q

List 2 disadvantages to use of spinous process instrumentation for management of vertebral fracture/luxations

A

Requires exposure of >5 vertebrae

Weak i.e. dont hold implants well

Dont provide that much stabilisation

(–> failure + biocompatibility i.e. Lubra plates = PVC)

31
Q

What was re-operation rate in fractures stabilised with lubra plates

A

38%

(spinous process necrosis)

32
Q

What % of cervical vertebral fractures involve C1 or C2

A

50 - 70%

33
Q

What is peri-op mortality rate for cervical fracture surgery?

A

10-36%

34
Q

What spinal cord segment gives rise to the phrenic nerve?

A

C5-C7

35
Q

What is the nerve supply to intercostal muscles?

A

Segmental intercosatl nerves

(under the UMN control of reticulospinal tracts, same as phrenic nerve)

36
Q

What is the usual approach for stabilisation of cervical vertebral fractures/luxations?

A

Ventral

37
Q

What are the two anatomical structures that have to be avoided with cervical vertebral column implants?

A

Vertebral canal and transverse foramen (not present in C7)

Cross-section of the C5 vertebra and surrounding musculature, illustrating implant corridors for bicortical implants (green) and monocortical implants (purple),

A Transverse foramen

B Vertebral vein

C Vertebral artery

D Vertebral foramen

38
Q

List 4 techniques for cervical vertebral fracture/luxation stabilization (excluding C2)

A
  1. Pins + PMMA (Oxley reported 3D printed guide for dens fracture (JSAP, 2016)
  2. Transverse process screws + curved steel bar + PMMA
  3. Ventrally applied monocortical screws + PMMA
  4. Locking plate
39
Q

What specific ‘step’ should be ensured when stabilising C2 fracture/luxation?

A

Cross AA joint with implants for increased stability

40
Q

List 3 plating systems that have been used clinically for cervical instability?

A
  • Cervical Spine Locking Plate (Synthes, human implant)
  • ComPact UniLock (Synthes, human implant)
  • SOP (Orthomed)
41
Q

What is the typical configuration of L7/S1 fracture luxations?

A

Caudal L7 fracture, ventral displacement

Characteristic appearance of a fracture-luxation of the L7-S1 articulation, with the sacrum and caudal fractured L7 body segment displaced cranially and ventrally to the remainder of the vertebral column. Note the degree of displacement of the laminae of the sacrum (long arrow) compared to the laminae of the L7 vertebra (short arrow).

42
Q

At what level does Sc end in large breed dogs, dogs <15kg and smal dogs/cats?

A

Large breed L4

<15kg dogs L6

Small dogs and cats L7

43
Q

List 4 methods to manage L7/S1 fracture/luxation

A
  1. Pins + PMMA
  2. SOP plate (Bilateral twisted SOP plates (Segal, JSAP, 2018))
  3. Pedicle screw-rod fixation (described for DLSS)
  4. Percutaneous transilial pinning in dogs (Di Dona, VCOT, 2016)
44
Q

What are the landmarks for L7/S1 screw placement?

A

L7: Enter just caudal to the base of the cranial articular process (the caudal border of the L6-L7 zygapophyseal joint), directed ventrally, slightly cranially and medially, contacting or exiting the cranioventral cortex of the vertebral body.

Sacrum: Enter just caudal to the cranial articular surface of the sacrum. Should be directed caudoventrolaterally through the sacrum and across the sacroiliac joint to achieve purchase in the long axis of the body of the ilium.

45
Q

Ho wlong can it take for ambulation to return?

A

4-6 months

46
Q

What is major cause of death in cervical fractures?

A

Respiratory arrest

47
Q

Dogs with cervical vertebral fractures/luxations are 13 times more liekly to have a functional outcome if…

A

Ambulatory on presentation

3: Neurosurgery (12 decks)

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