thoracolumbar trauma

Question 1

how do you perform a pedicle screw?

Answer 1

Entry point
Lumbar spine:
* lateral border of pars inter-articularis
* mid transverse process

Thoracic spine:
* Midpoint between - lateral border of pars inter-articularis and middle of facet joint
* mid transverse process

• Burr - decorticate entry site
• Pedicle probe inserted until resistance from anterior cortex of vertebral body
• medial to lateral trajectory based on level - 30deg S1 to 0 deg in T12 to 30deg T1
• superior/ inferior trajectory - based on preop imaging and image guidance intraop
• ball tip probe to check floor and walls of pedicle
• pedicle screw insertion - mono or polyaxial screw

Question 2

what is a chance fracture?

Answer 2

flexion distraction injury to the thorocolumbar spine
- middle and posterior columns fail under tension
- anterior column fails under compression
- Inherently unstable - TLIC score minimum 4

Types
* bony chance -
* soft tissue chance - difficult to heal

Question 3

how will you treat a chance fracture?

Answer 3

Considerations:
* stability
* cord involvement
* bone quality/ ankylosing

Surgery:
- posterior approach or if no decompression needed then minimally invasive
- pedicle screws and rod construct - stabilise
- decompress 2nd

Question 4

what is the TLIC score?

Answer 4

Thoracolumbar injury classification and severity score

Based on 3 parameters:
- injury morphology
- neurological status
- posterior ligamentous complex integrity

treatment implications
- score < 4 points = non-op
- score = 4 points = op or non-op
- score> 4 points = op

Question 5

why is the thorocolumbar junction more affected?

Answer 5

• at thoracolumbar junction there is fulcrum of increased motion that makes spine more vulnerable to traumatic injury
• thorocolumbar junction = T10-L2
• T10-T12 = attached to free floatins ribs - more mobilie than rest of thoracic vertebrae

Question 6

what is a burst fracture?

Answer 6

compression fracture of the vertebrae resulting from flexion fo the spine

Question 7

what are the anterior, middle and posterior columns?

Answer 7

Anterior column
- ALL
- anterior 2/3rd vertebral bodies

Middle column
- posterior 1/3 vertebral body
- PLL

Posterior column
- pedicles, lamina, facets and spinous process
- ligamentum flavum
- PLC

Question 8

what is the posterior ligament complex?

Answer 8

PLC is a key determinant of stability and consists of;
supraspinous ligament
interspinous ligament
ligament flavum
facet capsule

Question 9

how can you determine the integrity of the post ligamentous complex of the spine?

Answer 9

Conditions where the PLC is ruptured:
bony chance fracture
increased interspinous distance
progressive kyphosis with non-op
facet diastasis

indeterminant
- signal intensity between spinous processes on MRI

Question 10

what is the posterior thoracolumbar approach to the spine?

Answer 10

appropriately consented, marked and who checklisted patient
supine on a spinal table
image guidance for level

skin incision
- longitudinal midline incision
- for long fixation - 2 levels above and below

Dissection:
- skin, fat, fascia down to tips of the SP
- subperiosteal elevation of the paraspinal muscles (erector spinae) off the lamina
- lumbar spine - dissection limited to the facets unless fusion planed - preserve fascet capsule
- thoracic spine - dissection to the transverse process