Imaging of thoracic spine Trauma

Thoracic Spine
Trauma
Sunil Jeph MBBS, MD

Stabilizing anatomy of thoracolumbar spine

Intervertebral disks in load bearing and force
distribution during axial compression.

Normal anatomic configuration of the PLC
(Posterior ligament complex)

Anteriorly displaced center of gravity that creates a compressive force (dotted arrow) on
the spinal vertebrae similar to the force on the crane lifting arm. The resulting baseline
flexion force (solid arrow) on the PLC is similar to the tension on the crane’s lifting
cable

Critical factor for treatment decision making
Mechanical stability
Integrity of bone and ligamentous components.
Objective of treatment:
Prevent the development of neurologic injury
Prevent the development of progressive
deformity in response to physiologic loading and
a normal range of movement.

Thoracolumbar spine classification for clinical and surgical treatment.

Thoracolumbar spine classification for clinical and
surgical treatment.
Denis three-column classification system
Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification
Thoracolumbar Injury Classification and Severity Score (TLICS)

Based on Anatomic structures or proposed injury mechanism.
Denis three-column classification system:
This model is used to predict the soft tissue injury from bone
injury

Denis three-column classification system: Emphasis on the fracture involvement of the
“middle column,” (posterior half of the vertebral body and intervertebral disk and the
posterior longitudinal ligament)

Denis three-column classification system:
Spinal stability is dependent on at least two intact columns.
When two of the three columns are disrupted, it will allow
abnormal segmental motion, i.e. instability.
So a simple anterior wedge fracture or just sprain of the
posterior ligaments is a stable injury.
A wedge fracture with rupture of the interspinous ligaments
is unstable, because the anterior and the posterior column
are disrupted.
A burst fracture is always unstable because at least the
anterior and middle column are disrupted.

Criteria to predict soft-tissue injury from bony injury
are:
Angulation greater than 20 degrees.
Translation of 3.5 mm or more.

Major injuries
• Compression fracture
• Burst fracture
• Seat belt injury
• Fracture-dislocation
Minor injuries:
• Transverse process
fracture
• articular process fracture
• pars interarticularis
fracture
• spinous process fracture
Injury to the middle column renders the spine mechanically unstable

Modifications of the Denis classification:
Intact posterior ligamentous complex (PLC), two-column
unstable injuries can be successfully treated nonsurgically -
Unstable Stable.
All based on the premise that a fracture caused by forward
flexion should be treated by undoing the flexion by
positioning the patient in an extension brace, or by surgical
intervention correcting the spinal column in extension.
Some of the injuries thought to be due to extension
mechanisms, however, turn out to be due to flexion and vice
versa. These descriptions may thus be misleading.

Denis classification, Cons:
Does not provide prognostic information or consider the
patient’s neurologic status, and therefore it cannot adequately
guide surgical intervention.
Since it uses the terms stable and unstable. In many cases,
however, there is no good correlation with the necessity for
surgery

Stability
Ambiguous and may refer to:
Direct osseous stability
Neurological stability
Long-term (ligamentous) stability.

Arbeitsgemeinschaft für Osteosynthesefragen (AO)
classification
Types (9 subtypes in each)
Group A: vertebral body compression
Group B: anterior and posterior element injuries with
distraction. Transverse disruption either anteriorly or posteriorly.
Group C: anterior and posterior element injuries with rotation.
axial torque.

Arbeitsgemeinschaft für Osteosynthesefragen (AO)
classification
Pros:
• Highly detailed subclassifications, the AO system has shown
limited inter-observer variability.
Cons:
• Difficult to use.
• Does not incorporate the patient’s neurologic status.

Thoracolumbar Injury Classification and Severity Score
(TLICS) is a scoring and classification system developed
by the Spine Trauma Study Group .
• Scoring and classification system.
• Decide surgery vs no surgery
• Based on 3 components:
• Injury morphology (not mechanism).
• Integrity of the posterior ligamentous complex.
• Neurologic status of the patient.

Injury Morphology
If more than one injury morphology exists, the single injury with the largest score is used.
If multiple levels of injury are involved, each injury is assessed independently

PLC Integrity
SIGNS OF PLC DISRUPTION:
• Widening of the interspinous space.
• Avulsion fracture of the superior or inferior aspects of contiguous spinous processes,
• Facet joints: widening, empty (“naked”), perched or dislocated.
• Vertebral body translation or rotation.

Normal PLC anatomy
MR imaging is the standard of reference for detecting PLC injury.

• Except, vertebral body translation or interspinous widening, osseous
findings such as a loss of vertebral body height and kyphosis have been
found to be unreliable in assessing PLC integrity because of the inverse
relationship between osseous destruction and ligamentous injury.
• Patients with severe osseous destruction may have less risk for PLC injury
because the vertebral injury dissipates energy, thereby sparing adjacent soft
tissues.
• Conversely, patients with a significant translation or rotation injury and less
vertebral fragmentation may have a higher risk for PLC injury.
• PLC must be directly assessed at MR imaging regardless of the severity of
vertebral body injury seen at CT

Axial compression with mild flexion, which results in nearly asymmetric height loss of
the anterior and middle columns and minimizes the risk of distraction injury to the PLC

Flexion-distraction mechanism and PLC
injury should also be suspected if a
superior or inferior posterior endplate
fracture is seen because this likely reflects
an avulsion fracture from the
comparatively strong annulus fibrosus of
the intervertebral disk.
PLC injuries can occur in this setting
with minimal kyphosis or vertebral body
height loss, a fact that further underscores
the importance of MR imaging in

Posterior endplate fracture with flexion-distraction
mechanism and PLC injury.

Neurologic Status
Although clinical neurologic
status cannot be directly
determined at imaging, a cord or
nerve root injury identified on
MR images should be included in
the imaging report with the
percentage of spinal canal
narrowing .

Axial compression with significant burst fracture of the vertebral body, bone
retropulsion into the spinal canal, and resultant risk of neurologic injury.

• Anterior vertebral body compression percentage: percentage of anterior
vertebral body compression with respect to the average height of the anterior
vertebral bodies immediately cephalad and caudad to the injury level .
• Retropulsion: distance of a line drawn between the posterior margins of the
adjacent vertebral bodies and the most posterior margin of the bone fragment.
• Sagittal canal diameter: distance between the posterior canal border and the
anterior canal border.
• Posterior canal border: convergence of the superior margins of the left and
right laminae at the midline of the spinous process.
• Anterior canal border: posterior extent of the retropulsed midvertebral body.

Treatment
TLICS addresses three different categories of spine stability:
Immediate mechanical stability, suggested by injury morphology
Long-term stability, indicated by PLC status
Neurologic stability, indicated by the presence or absence of a neurologic deficit

Burst fracture, in the absence of a neurologic deficit is controversial
Osseous retropulsion alone does not imply neurologic injury or indicate a
need for surgical decompression.
Thoracic spine injury with retropulsion may cause significant neurologic
injury because the spinal canal in the thoracic area is narrow and blood
supply to the cord is sparse.
Lumbar spine fracture may result in marked displacement of the cauda
equina but no neurologic deficit because of the wider canal and cord
termination near L1
Highly comminuted vertebral body fracture is more likely to deform under
physiologic loading and may require short-segment posterior fixation and
anterior fusion or long-segment posterior fixation. In the absence of a
neurologic deficit, PLC integrity should be confirmed at MR imaging,
especially if conservative management of burst fracture is planned

TLICS can help guide the surgical approach

21-year-old female who presented after sustaining a seatbelt type injury. She had
an exploratory laparotomy for repair of a ruptured duodenum.
There was no neurologic deficit.

first described by G. Q. Chance in 1948
most common site: thoracolumbar junction (T12-L2)
"seat belt injury" due to sudden forward flexion in a
head-on automobile collision while being restrained
by a lap belt.
advent of both lap and shoulder belts in the 1980s,
Chance fractures have become less common

31 year old male. He was working on a roof, fell
approximately 5 meters landing on his feet. He complained of
pain in left lower extremity and lower back.

21-year-old woman presented with back pain after a motor vehicle
collision in which she was an unrestrained passenger in the
middle seat. CT and MR imaging findings are shown.

Injury morphology (burst) = 2
PLC integrity (indeterminate) = 2
Neurologic status (normal) = 0
TOTAL=4
(Burst fracture
PLC integrity indeterminate)

21-year-old man presented with multiple injuries
and lower extremity paralysis after a high-speed
motor vehicle collision in which he was an
unrestrained driver.

Injury morphology (translation) = 3
PLC (disrupted) = 3, and
Neurologic status (cord injury) = 3
TOTAL = 9

29-year-old man presented with complete paralysis after he
collided with a telephone pole while driving a motorcycle.

Injury morphology (distraction) = 4
PLC (disrupted) = 3
Neurologic status (paralysis) = 2
Total = 9

17-year-old girl presented with right-sided
radiculopathy after a motor vehicle collision in
which she was an unrestrained backseat passenger.

Injury morphology (translation) = 3
PLC (disrupted) = 3
Neurologic status (nerve root injury)
= 2.
TOTAL = 8

Checklist for Reporting Spine Injury: CT
Indirect findings

Checklist for Reporting Spine Injury: MR

Radiology report may include the TLICS total score
if there is clear imaging evidence of neurologic injury.
Generally the report will not include the total score if
the patient’s clinical neurologic status is unknown.

References:
• Khurana B, Sheehan SE, Sodickson A, Bono CM, Harris MB.
Traumatic thoracolumbar spine injuries: what the spine surgeon
wants to know. Radiographics. 2013 Nov-Dec.
• Radiology assistant
• A Magerl F1, Aebi M, Gertzbein SD, Harms J, Nazarian S.
comprehensive classification of thoracic and lumbar injuries. Eur
Spine J. 1994;
• Google images

Imaging of thoracic spine Trauma

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