Chapter 34 Vertebral Fractures, Luxations and Subluxations Flashcards
(47 cards)
What is reported prevalence of vertebral column fractures/luxation/subluxations in dogs treated for severe blunt trauma?
10%
List the 5 types of primary SC injury
- Concussion
- Compression
- Shearing
- Laceration
- Elongation
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
- Abdominal trauma approx 10%
- Multiple vertebral column fractures/luxation/subluxations approx 20%
- Thoracic trauma approx 30%
- Concurrent fractures approx 40%
What is the most important prognostic factor for recovery following Sc injury?
Presence of nociception
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
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
What is the sensitivity and specificity of radiography for diagnosis of vertebral column fractures?
And subluxations
Sensitivity fractures 72%
Sensitivity subluxations 77%
Particularly poor for detecting injury to dorsal and middle compartment
Describe the three compartment model of vertebral fractures.
What anatomical structures make up each compartment
- 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.
What are the three anatomic structures (the principal contributors of vertebral column stability) used in the simpler vertebral fracture classification scheme
- Zygapophyseal joints
- IV disc
- Vertebral body
What anatomical structure is the principal anatomic contributor to rotational stability of the vertebral column?
Intervertebral disc
How do isolated vertebral body fractures compare to isolated zygapophyseal joint fracture (even if bilateral)
Vertebral body fracture = very unstable
Zygapophyseal joint fracture can be relatively stable
Based on 3 compartment model and anatomic classification scheme, when is a fracture considered unstable?
If ≥ 2 compartments/structures compromised
What are the three goals of surgery for vertebral fracture/luxation/subluxation
Realignment
Stabilization
Decompression
What 3 owner expectations have to be met if pursuing sx in paralysed/nociception -ve cases?
- Surgery is for provision of pain releif
- Permanent paralysis
- Permanent incontinence
What % of peripherally located axons are necessary for restoration of walking?
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)
How does reperfusion injury result in Sc injury?
Reperfusion –> release of oxygen-derived free radicals –> lipid peroxidation of neuronal and gial cell membranes
List 5 indications for surgical intervention in vertebral fractures/luxationssubluxation
- Neuro defecits (with intact nociception)
- Worsening neuro status
- Intractable pain
- Unstable
- Sc compression
HOw can correct fracture/luxation reduction be assessed?
Check zygapophyseal joints
Label the diagram
What is the relationship between pin bending strength and radius
proportional to radius4
(area moment of inertia)
What pin + pmma construct has been shown to be as intact vertebral column ex vivo
four pins + pmma (i.e. one pin on each side of vertebra)
What are recommended pin entry points in thoracic vertebrae?
And lumbar vertebrae?
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
What are recommended pin insertion angles (from vertical) in thoracic and lumbar vertebrae?
And from ventral approach in cervical vertebral column
Thoracolumbar: In summary 30 - 60º
Cervical: 34 - 38º (can be increased in C7 as no transverse foramen to avoid)
What structures can be damaged by pins placed through transcortex of vertebral bodies?
Azygous vein, aorta, pleura, lung.
If excessive bleeding is encountered during vertebral body pin placement, which 2 structures might have been damaged?
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).
