Vertebral fractures Flashcards
In what percentage of patients with vertebral luxation/fracture are concurrent injuries present?
45-83%.
Thoracic trauma: 15-25%.
Abdominal trauma: 6-15%.
Pelvic fractures: 14-48%.
In what percentage of cases with vertebral luxation/subluxation are multiple fractures/luxations present?
15-20%. Dogs weighing <15kg more predisposed to multiple fractures.
Survey radiographs of the entire vertebral column are recommended to rule out multiple injuries.
Is absent nociception associated with a worse prognosis for patients with IVDH or vertebral fracture?
Vertebral fracture, luxation or subluxation. Only 12% of dogs in one study regained ambulation.
80-90% of cases with intact nociception can achieve good outcomes.
What imaging modalities might be used for work-up of vertebral luxation/fracture?
- Radiography.
- Myelography.
- CT: allows for the most accurate determination of vertebral canal stability.
- MRI: provides useful information regarding the paraspinal soft tissues, intervertebral discs, and ligamentous support structures (which provide vertebral stability), as well spinal cord injury.
What is associated with a negative outcome in dogs with vertebral fracture/luxation based on radiographs?
Degree of dislocation. 100% dislocation and absence of nociception warrants a grave prognosis.
What parts of the vertebral canal is radiography particularly poor at evaluation?
The dorsal and middle compartments. Also lacks sensitivity for detection of fracture fragments within the vertebral canal or spinal cord compression.
Overall sensitivity only 72%.
What are the anatomic classifications in the three compartment model of vertebral stability?
Dorsal, middle and ventral. If more than one of these compartments is compromised the vertebral column is considered unstable and surgical intervention is recommended
What comprises the dorsal, middle, and ventral compartments of the vertebral column?
Dorsal: spinous processes, vertebral laminae, articular processes, vertebral pedicles, and dorsal ligamentous complex (supraspinous ligament, interspinous ligament, joint capsule of the zygapophyseal joints, and ligamentum flavum).
Middle: dorsal longitudinal ligament, the dorsal portion of the annulus fibrosus, and the dorsal portion of the vertebral body.
Ventral: remainder of the vertebral body, the lateral and ventral portions of the annulus fibrosus, the nucleus pulposus, and the ventral longitudinal ligament
What are the three principle contributors to vertebral instability as per the simpler classification model of vertebral stability?
Intervertebral disc: primarily responsible for rotational stability, also involved in lateral bending. Vertebral body may provide some buttressing in bending if still intact with disc injury.
Vertebral body: bending forces and axial compression. Fracture of the vertebral body alone is likely to be very unstable.
Articular process: resists all forces. Isolated fracture of one or both articular process may not result in vertebral instability.
Injury to more than one of these compartments should be considered unstable.
Describe a treatment algorithm for vertebral fractures/luxations
Has the use of corticosteroids been shown to improve outcomes following vertebral fracture/luxation?
No.
Their proposed use has been related to their anticipated function as an antioxidant, which may help to reduce secondary spinal cord injury.
What are non-surgical treatment options for vertebral luxation/sublxuation?
Cage rest +/- external coaptation.
Which patients are the best candidates for external coaptation?
Small patients with minimal neurologic dysfunction, intact ventral buttress and lack of concurrent thoracic, abdominal or pelvic injuries
External coaptation is unlikely to realign the vertebral column.
Lesions in the lumbosacral vertebral column might be most forgiving.
When external coaptation is used for treatment of vertebral fracture/luxation what is the extent of splint material that is required for stability?
Lumbar: should include whole pelvis
Cervical: should go to level of eyes (to stabilize the atlanto-occiptal joint) and midthorax.
Ideally maintained for a minimum of 4 weeks.
When is surgery indicated for a patient with vertebral luxation/subluxation?
- Paretic animals with intact nociception.
- Worsening neurologic status or unstable fractures.
- Spinal cord compression.
What surgical techniques are primarily used for TL vertebral fracture/luxation stabilization?
- Pins PMMA.
- Ex-fix.
- Locking plates (SOP most frequent, lateral LCP described).
These techniques can all be used with compromised integrity of two or more vertebral column compartments.
Additional techniques include:
4. Spinal process plating.
5. Spinal stapling.
What are the main vascular structures that are at risk during pin placement for vertebral fracture stabilization?
The azygous lies just ventral to the right thoracic vertebral column (often within 1mm of vertebral body). Aorta, pleura and lung are also in close proximity to thoracic vertebrae.
In the lumbar vertebrae these structures are somewhat protected by the presence of the hypaxial muscles.
What is the pin entry point for pin and PMMA constructs?
Lumbar: between the base of the transverse process and the accessory process.
Thoracic: level of the accessory process or tubercle of the rib.
Pins should be directed cranially in the cranial vertebra, and caudally in the caudal vertebra to engage the end plates.
What are the ideal pin insertion angles for TL vertebral stabilization?
30-60 degrees.
If bleeding is encountered during drilling of the pilot hole for pin placement in TL vertebral stabilization what structures might be responsible?
Might be penetration of vertebral venous plexus, or damage to the centrally located basivertebral veins
How many pins are required to provide adequate stabilization of a TL vertebral fracture/luxation?
4 pins and PMMA shown to have equivocal stiffness in extension, flexion and rotation as the intact vertebral column in biomechanical testing
What are the most common implants used for plating of vertebral fracture/luxation?
SOP plate: typically applied bilaterally, at similar angles as those described for pin/PMMA fixation. Recommend at least 3 screws per vertebra total (between the two constructs). Engagement of the far cortex is not essential for stability.
LCP: can be applied laterally to the vertebral body to allow for application of compression. Not as strong as a pin/PMMA construct but still stronger than the intact vertebral column.
Due to their close proximity to the intervertebral foramina may cause impingement on the spinal nerves.
What are options for stabilization of vertebral fractures/luxations using the spinous processes?
1) Bilateral spinal plating using Auburn metal plates, or Lubra plastic plates.
2) Spinal stapling.
What are the main differences between cervical and thoracolumbar stabilization?
Ventral approach for cervical stabilization. Cervical pedicles are narrow and transverse processes have transverse foramina that contain the vertebral arteries, veins and nerves. This makes safe passage of implants challenging. Pin insertion angles are varied and should be determined based off CT pre-op, although angles of 20-35 degrees have been described.
How does fixation of the fractures of the C2 vertebra differ from fractures of the other cervical vertebrae?
The C2 vertebra has a thin body with little purchase for implants. Ideally ventral fractures should be stabilized using the addition of implants that cross the C1/C2 joint space (angled 40 degrees in the transverse plane toward the alar notch, and 20-30 degrees in the sagittal plane).
Implant placement in the body of C3 should be considered for caudal C2 vertebral body fractures.
What are some locking plate systems described for cervical fracture fixation?
- Cervical spine locking plate (CSLP, Synthes –humans)
- UniLock (Synthes –human maxillofacial reconstruction plate)
- String of Pearls (SOP –Orthomed)
- LCP plate (Synthes)
What is the most common imaging presentation of LS fracture/luxation?
Cranioventral sacral displacement with small caudoventral wedge fracture of the L7 body
Why is placement of implants relatively easier in the L7 vertebra than other vertebral sites?
Relatively thicker pedicles.
What are the landmarks for insertion of implants in L7 and the sacrum during repair of fracture/luxation?
L7: just caudal to the cranial articular process, directed cranially and medially.
Sacrum: just caudal to the cranial articular process, directed caudally and laterally. Should engage the long axis of the body of the ilium (via the SI joint) for increased purchase and security.
What technique was used by Bitterli 2022 in VCOT for successful repair of thoracolumbar spinal fractures and luxations? What were the most common complications?
Unilateral uniplanar percutaneously placed (under fluoroscopic guidance) ESF (type 1a).
Erythema, exudation and pin loosening were the most common complications.
