imaging of thoracic spine trauma

Thoracic Spine Trauma

Thoracic Spine TraumaSunil Jeph MBBS, MD

Biomechanics

1. The upper thoracic region (T1-T8) is rigid due to the ribcage which provides stability.2. The transition zone T9-L2 is the transition between the rigid and kyphotic upper thoracic part and the flexible lordotic lumbar spine. This is where most injuries occur.3. Finally we have the L3-Sacrum zone which is flexible and this is the region where axial loading injuries occur.

Stabilizing anatomy of thoracolumbar spine

coronal orientation of the thoracic facet joints minimizes extension but allows rotation.sagittal oblique orientation of the lumbar articular facets minimizes rotation

1. The anterior portion of the functional unit contains two aligned vertebral bodies, the intervertebral disk, and the anterior and posterior longitudinal ligaments. 2. The posterior portion consists of the vertebral arches, facet joints, and posterior elements.

Mechanism of injury

1. Upper thoracic spine: center of gravity is anterior to the spine.Axial loading will result in compressive forces anteriorly and tensile forces posteriorly. This will result in flexion-type of injuries.

2. lumbar spine due to the lordosis, the center of gravity is posteriorly.Flexion type of injuries will straigthen the lumbar spine and result in axial loading.In this area we will see burst fractures.

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

The vertebral bodies resist compressive loading.The intervertebral disks contain a central nucleus pulposus that absorbs and hydrostatically distributes compressive loading and an annulus fibrosus that resists the resulting circumferential tensile stress

Normal anatomic configuration of the PLC(Posterior ligament complex)

In axial compression injury, PLC, plays a critical stabilizing role. PLC: supraspinous ligament- strong cordlike ligament that connects the tips of the spinous processes from C7 to the sacrum. high collagen content, and their high tensile strength limits flexion of the spine interspinous ligaments - weaker, thin, membranous structures that connect the adjacent spinous processes. high collagen content, and their high tensile strength limits flexion of the spine articular facet capsules - ligamentum flavum - thick broad structure that connects the laminae of the adjacent vertebrae. high elastin content and exerts a contractile force on the vertebral arches when it is elongated during flexion

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 cranes lifting cable

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

Thoracolumbar spine classification for clinical and surgical treatment.


Denis three-column classification system Arbeitsgemeinschaft fr 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 injuryDenis three-column classification system

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 fractureBurst fractureSeat belt injuryFracture-dislocation Minor injuries:Transverse process fracturearticular process fracturepars interarticularis fracturespinous process fractureDenis three-column classification systemInjury 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 patients 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

StabilityAmbiguous and may refer to:Direct osseous stabilityNeurological stabilityLong-term (ligamentous) stability.

has strong emphasis on stability. But stability is ambiguous




Arbeitsgemeinschaft fr Osteosynthesefragen (AO) classification Types (9 subtypes in each) Group A: vertebral body compressionGroup 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.

Group A through C represent a continuum of progressively increasing injury severity and instability, with a concomitant increasing likelihood of the need for surgical stabilization

Arbeitsgemeinschaft fr Osteosynthesefragen (AO) classification Pros: Highly detailed subclassifications, the AO system has shown limited inter-observer variability. Cons:Difficult to use. Does not incorporate the patients 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.

The need for a reliable, reproducible, clinically relevant, prognostic classification system with an optimal balance of ease of use and detail of injury description led to the development of Thoracolumbar Injury Classification and Severity Score.Pattern-based approach for efficient imaging interpretation and communication with spine surgeons

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

(a) compression fracture (1 point) - loss of vertebral body height or disruption of the vertebral endplate.(b) Compression with burst fracture (2 points) - involve the posterior vertebral body with retropulsion.(c) translation or rotation injury (3 points) - horizontal displacement or rotation of one vertebral body with respect to another. (d) distraction injury (4 points) - anatomic dissociation along the vertical axis and can occur through the anterior and posterior supporting ligaments, the anterior and posterior osseous elements, or a combination of both

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.

protects the spine from excessive flexion, rotation, translation, and distraction.If disrupted, the injured segment of the PLC usually requires surgical intervention because of its poor healing potential. Without surgery, an injured PLC can result in kyphotic progression and subsequent vertebral collapse

Normal PLC anatomy

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

Mild superior endplate compression fracture of T12 with an intact PLC. Sagittal T1 and axial T2.white arrow: supraspinous ligamentblack arrow: interspinous ligamentarrowhead: ligamentum flavum

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

PLC injury scenarios

PLC injury scenario: 1

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

Greater flexion component increases the risk for a destabilizing PLC injury.

17-year-old woman after a mechanical fall. (a) Sagittal CT image shows a compression fracture with predominant involvement of the anterior column (arrow), resultant kyphotic curvature (dotted line), and mild fanning of the spinous processes at the level of injury. (b) Sagittal CT image of the lateral vertebral bodies shows facet perching (arrow) with articular facet fracture, findings suggestive of a significant flexion component to the injury. (c, d) Sagittal T1-weighted (c) and STIR (d) MR images at the same level as a and b show disruption of the supraspinous ligament (black arrow) and ligamentum flavum (white arrow). Edema (arrowhead in d) in the posterior soft tissues and interspinous ligament is better visualized on the STIR image and illustrates the severity of the PLC injury.


Increased flexion component of the injury mechanism, which results in asymmetric height loss with increased anterior wedging. Relative height maintenance of the middle column exacerbates the distraction force on the PLC and results in a destabilizing injury.

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 assessing fracture stability.

Flexion injury of L1. (a, b) Sagittal T1-weighted (a) and STIR (b) MR images show avulsion of the posterior margin of the inferior endplate (arrowhead) and minimal anterior column compression (* in a). Fanning of the spinous processes (bracket in a) and disruption of the dark lines of the supraspinous ligament (black arrows in a) and ligamentum flavum (white arrows) are seen. Complete disruption of the interspinous ligament is shown (black arrow in b). (c) Axial T2-weighted MR image at the same level as a and b shows hemorrhage and edema throughout the PLC and no identifiable ligamentum flavum in the expected location (arrow), a finding indicative of disruption with retraction.


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

Incomplete spinal cord injury or cauda equina syndrome is assigned 3 points because patients with this type of injury may receive greater potential benefit from surgical decompression than patients with complete spinal cord injury or no initial neurologic 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 .

Thoracolumbar spine injury in a 38-year-old man. (a) Sagittal CT image shows a burst fracture of L1 (arrow) with fragment retropulsion into the spinal canal. (b, c) Sagittal (b) and axial (c) T2-weighted MR images show bone retropulsion with near-complete obliteration of the spinal canal (white arrow) and associated signal intensity change within the cord at a level superior to the injury (arrowhead in b). Disruption of the ligamentum flavum (black arrow) is also seen, a finding indicative of severe PLC injury.

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 morphologyLong-term stability, indicated by PLC statusNeurologic 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

based primarily on the patients neurologic status and the integrity of the PLC

Compression fracture of L1. (a) In one patient, sagittal T1-weighted MR image (a) shows vertebral body compression and fragment retropulsion into the spinal canal but no clear PLC disruption. Postoperative lateral radiograph (d) shows the anterior (anterolateral) surgical approach used. (b, c) In another patient, sagittal T1-weighted MR image (c) shows complete disruption of the PLC but minimal vertebral body compression and no significant retropulsion. Lateral radiograph (e) shows the posterior surgical approach used. (c) In a third patient, sagittal T1-weighted MR image (e) shows significant vertebral body compression, fragment retropulsion, and PLC disruption. Lateral radiograph (f) shows the combined anterior and posterior surgical approach used. The anterior approach included a vertebral body implant cage, lateral body plate, and screw fusion.

Case 1

31 years old man: Trauma

Jumper's fracture

fracture of the calcaneus and a lumbar spine fracture.it is clear that we are looking at an unstable fracture, because this is a burst fracture.Both the anterior and the middle column are disrupted.In addition there is edema in the posterior soft tissues indicating that there is also involvement of the posterior column.Notice also the marrow edema in the adjacent bodies due to the severe axial loading.

Case 2

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.

Chance fracture

classic example of a chance fracture, which is a three column injury with a horizontal orientation of the fracture.

What is unique about the Chance fracture is the horizontal orientation, which is nicely demonstrated on the sagittal reconstructions

coronal reconstructions we can see the horizontal orientation of the fracture.

Mechanism of chance fracture

first described by G. Q. Chance in 1948most 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

Chance variant

This is a pure ligamentous injury, which is analogous to bilateral interfacet dislocation, which is also a pure ligamentous injury.There is rupture of the interspinous ligament, dislocation of the facet joints and a horizontal rupture of the disc.

Pure ligamentous and combined osseous / ligamentous variants have an increased risk of instability compared to the osseus type.It is imperative to look for a split of the posterior elements, disc widening or widening of the spinous processes and facets.

Case 3

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.

hyperflexion injury of L1 with involvement of the anterior column and possible involvement of the middle column.

Posterior part of the vertebral body is of normal height, but there is some involvement of the posterior part of the vertebral body.If you are aggressive you could call this a two column injury, which would require stabilizing surgery.If you are conservative you could call this an injury with only minor involvement of the middle column.

coronal reconstruction and an axial image at the level of the fracture.Next step- Continue with the MR.

MR images show bone marrow edema in the involved vertebral body, but no additional soft tissue injury.Since, MR did not show any additional findings, this patient was treated as having a single column injury.Consultation with orthopedic surgery recommended conservative management with a TLSO brace.There is a tendency to treat these thoracolumbar injuries conservatively, even if there is slight involvement of the middle column.

Case 4

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) = 2PLC integrity (indeterminate) = 2Neurologic status (normal) = 0

TOTAL=4 (Burst fracture PLC integrity indeterminate)

Compression burst fracture. (ac) Sagittal CT image (a) and sagittal T2-weighted (b) and STIR (c) MR images show a fracture of L1 (white arrow) with significant fragment retropulsion but no cord or conus medullaris signal intensity abnormality. There is mild soft-tissue edema (arrowhead in c) and edema in the supraspinous and interspinous ligaments (black arrow in b and c) without definite ligament disruption. The ligamentum flavum appears intact. (d) Axial T2-weighted MR image shows a mild degree of impression on the thecal sac at the level of injury (arrow). The injury was classified as a burst fracture with indeterminate PLC status, and a posterior surgical approach was chosen because of clinical instability. At surgery, the interspinous ligament was found to be injured

Injury morphology (burst) = 2PLC integrity (indeterminate) = 2Neurologic status (normal) = 0

TOTAL=4 (Burst fracture PLC integrity indeterminate)

Case 5

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

Anterior translation injury. Sagittal CT (a) and T2-weighted MR (b) images show a translation injury of T12 and L1 with secondary flexion. There is prominent widening of the interspinous space (bracket in a) and an annulus avulsion fracture of the inferior endplate of T12 (white arrow). Severe cord compression with signal intensity change (black arrow in b) and disruption of the supraspinous ligament (black arrowhead in b) and ligamentum flavum (white arrowhead in b) are seen. The patient underwent posterior-approach open reduction and stabilization.

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

Patient underwent posterior-approach open reduction and stabilization.

Case 6

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

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

Distraction injury. Sagittal CT image (a) and sagittal STIR (b) and axial T2-weighted (c) MR images show a distraction injury of T10 (white arrow in a) with fracture line extension through the middle and posterior columns and subsequent distraction of the posterior element fracture fragments. Disruption of the ligamentum flavum (arrowhead in b), interspinous ligament (white arrow in b and c), and supraspinous ligament (black arrow in b and c) is seen. The patient underwent posterior-approach surgical repair

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

Case 7

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

Thoracic spine lateral translation injury. Coronal CT image (a) and sagittal T2(b) and axial (c) T2-weighted MR images show a lateral translation injury of T11 and T12 with lateral vertebral body overlap and marginal fractures (arrows in a), lateral canal compression with T11 nerve root injury (white arrow in b and c), and ligamentum flavum disruption (black arrow in b and c). The patient underwent posterior-approach surgical repair

Injury morphology (translation) = 3PLC (disrupted) = 3Neurologic 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 patients 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 assistantA 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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