Image interpretation of the spine

Question 1

Vertebra: Classification: irregular bones

Answer 1

Divided into five groups
Cervical – consists of 7 vertebrae
Thoracic - consists of 12 vertebrae
Lumbar - consists of 5 vertebrae
Sacral - consists of 5 fused vertebrae
Coccyx - consists of 4 fused vertebrae

Question 2

Structure of a typical vertebra

Answer 2

Consists of:

Body (anterior part) – cylindrical in shape. Anterior aspect convex, posterior aspect concaved. Superior and inferior aspects are flat.

Vertebral arch (posterior part) – consists of seven processes:
Pedicles (paired)
Laminae
Spinous process
Transverse process
Articular process
Pars inter articularis
Intervertebral foramina.

The vertebral foramen is enclosed between the body and the vertebral arch. (Contains the spinal cord)

Question 3

Spinal Injury Mechanisms

Answer 3

RTA’s 45%
Falls 20%
Recreation/Sport 15%
Intentional Violence 15%
Other 5%

Male dominance M:F = 4:1

Question 4

Atypical vertebrae- Atlas - First, second, seventh cervical vertebra

Answer 4

Consists of
Anterior arch – contains anterior tubercle
Posterior arch– contains posterior tubercle
Two lateral masses
Larger transverse process
No body

Axis – Second cervical vertebra
Main feature odontoid process

Seventh cervical vertebra
Consists of a prominent spinous process that is not bifid
Transverse process large

Question 5

What is the Fracture Prevalence?

Answer 5

Fractures of C5/C6
are most common. This is because most injuries are due to hyperflexion, with the maximum force being focused upon the vertebral bodies of C4-C7.
In children under 8 years
fractures are infrequent. If they do occur, they are likely to involve C1/C2.

Injuries of the cervical spine produce neurological damage in approximately 40% of cases. Due to burst fractures or facet joint dislocations

Question 6

Lateral Radiograph description

Answer 6

The majority of detectable abnormalities will be visible on the lateral radiograph.
anatomical lines should be traced:
anterior vertebral body cortex
posterior vertebral body cortex
spinolaminar junction
Posterior Spinal Line

Alignment of C7 with T1 must be demonstrated.
If not on the initial lateral, a swimmer’s view or trauma obliques will demonstrate this area.

Soft tissue
An increase in the retropharangeal soft tissues may be caused by haemorrhage or oedema

C1 - C4 = 4-7mm (should “hug” the anterior cortex)
C5 - C7 = 16-20mm (roughly equal to vertebral body)

Lateral masses of C1 should not overhang the lateral masses of C2. If present, this is indicative of a burst fracture:

Question 7

Ap radiograph

Answer 7

The AP radiograph is often overlooked, however, some fractures that are not visible on the lateral radiograph will be visible on the AP.

Assess:
Superior and inferior endplates
Spinous processes
Lateral masses

Question 8

Peg View

Answer 8

Open Mouth Radiograph (C1/C2)

This view enables assessment of C1 and C2 (fractures of the odontoid peg.

Often more visible on thelateral projectiondue to subsequent anterior / posterior displacement.

There should be symmetric space between the odontoid peg and lateral masses of C1.

However, beware that normal asymmetric widening may be seen due to rotation of the patient’s head.

Question 9

What is a Neural arch fracture?

Answer 9

Longitudinal fracture through the posterior neural arch, usually bilateral.

It is caused by hyperextension, with the result that the neural arch of C1 is compressed between the occiput and C2.

It is best demonstrated on the lateral projection.

Question 10

What is a Burst (Jefferson) fracture?

Answer 10

Comminuted fracture, with bilateral disruption of both anterior and posterior arches, and lateral displacement of both lateral masses.

It is caused by axial compression with the transmission of force from the skull downwards through the occipital condyles, compressing the lateral masses.

Demonstrated on the open mouth view by:
unilateral C1/C2 odontoid peg joint space widening.
lateral masses of C1 overhang the lateral masses of C2.

Question 11

What is an Axis (C2) Odontoid peg fracture?

Answer 11

This is the most common fracture of C2

Caused by flexion or extension and usually results in ligamentous instability.

Usually involves the base of the peg.

Can be visualised on either the open mouth or, more commonly, lateral view.

Assess for any soft tissue swelling anteriorly. Also look carefully at Harris’ ring on the lateral projection.

Question 12

What is a Anterior wedge compression fracture?

Answer 12

Caused by hyperflexion

The vertical height of the vertebral body is decreased anteriorly

Visible on lateral radiograph

The posterior elements remain intact. This is a stable injury.

Question 13

What is a Burst fracture?

Answer 13

Caused by axial compression

The intervertebral disc is driven into the vertebral body below.

The vertebral body explodes into several fragments

A fragment from the postero-superior surface being driven posteriorly into the spinal canal.

This is an unstable injury that frequently results in spinal cord injury.

It is therefore important to check the posterior vertebral cortex for evidence of disruption

Question 14

What is a Bilateral locked facets?

Answer 14

If the amount of distraction increases, the facets may become disarticulated.

The vertebral body is displaced anteriorly by 50%

the inferior facets of the anteriorly displaced vertebra lie anterior to the superior facets of the vertebra below.

Assess both anterior and posterior vertebral lines.

look carefully at the facet joints; they should have a “roof tile” appearance, parallel to one another.

Force has caused the articulating facets to come apart and lock in place.

Question 15

What is a Teardrop extension fracture?

Answer 15

Hyperextension causes a triangular fragment to be avulsed off the antero-inferior corner of the vertebral body.

This is not associated with any neurological damage.

The axis is most commonly involved.

Question 16

What is a Spinous Process Fracture?

Answer 16

Avulsion by the supraspinatous ligament off the spinous process

Usually C6 or C7

Caused by flexion as the body rotates relative to the head and neck.

Usually undisplaced and therefore only seen on the lateral radiograph

Question 17

What is Spondylosis?

Answer 17

Refers to degenerative changes of the intervertebral disc spaces, which is demonstrated by disc space narrowing, endplate sclerosis and osteophyte formation.

Facet joint OA is seen posteriorly. The associated osteophytes may impinge on the nerve root foramina.

The appearance of significant degenerative changes within the cervical spine may obscure underlying injury. It is therefore important to search for co-existant trauma.

A common mechanism of injury in those patients with spondylosis (often the elderly) is a fall directly onto the forehead with a subsequent fracture at C2

Question 18

What is Metastatic Disease?

Answer 18

Primary tumours can metastasise to the vertebral bodies demonstrating a lucent, moth-eaten, permeative appearance.

There is often subsequent collapse.

Question 19

Thoracolumbar Spine

Answer 19

60-70% of thoracolumbar spine fractures in adults occur at T12, L1 and L2.

90% of all fractures being seen between T11 and L4.It is therefore important that T11/T12 is included on all trauma lumbar spine radiographs.

20% of thoracolumbar fractures are seen in association with other skeletal injuries.

Question 20

Assess on both spine images

Answer 20

Height of vertebral bodies should be equal.

Width of intervertebral disc spaces should be uniform.

Continuity of superior and inferior endplates: should remain unbroken.

Distance between spinous process should be equal.

Trace the posterior elements; the pedicles, laminae, and spinous processes.

Question 21

The spine may be split into three “columns” for the purpose of assessment of stability. What are the 3 columns?

Answer 21

Anterior column - Involves the anterior two thirds of the vertebral body/intervertebral disc, and the anterior longitudinal ligament.

Middle column - Involves the posterior aspect of the vertebral body/intervertebral disc, and the posterior longitudinal ligament.

Posterior column - Involves the posterior elements - the lamina, facet joints, spinous processes, and the associated ligaments.

Question 22

An injury to the spine is considered unstable if two of the three columns are disrupted. What are examples of this?

Answer 22

Generally, if the middle column is disrupted, either the anterior or posterior columns are also involved, and the injury is unstable.

The middle column is the fulcrum from which the spine pivots into flexion and extension.

It is generally thought that the middle column remains intact, and is therefore stable, in simple flexion and extension injuries.

Axial compression, distraction and rotational injuries, or a combination of these with flexion or extension, usually disrupt the middle column.

Question 23

What is a Wedge Compression Fracture?

Answer 23

Forward flexion causes wedge compression deformity of the anterior vertebral body

the normal posterior concavity of the vertebral body remaining intact.

Often occurs in association with fracture to the superior endplate.

Question 24

What is a Chance Fracture?

Answer 24

May occur with use of seat belt during a deceleration injury.

Refers to compression fracture of the vertebral body with transverse/horizontal fractures of the posterior elements

With an increase in distraction, the AP will demonstrate an “empty” vertebral body, as the posterior elements will not be superimposed on the vertebral body.

There will be an increase in the inter-spinous distance and a break in continuity of the pedicles or spinous process.

Lateral will show an increase in the inter-spinous distance with horizontal fractures of the spinous process/lamina/pedicles running into the vertebral endplates.

Question 25

Whta is a Fracture-dislocation?

Answer 25

The anterior and posterior vertebral lines will demonstrate malalignment, with disruption of the facets posteriorly.

Occurs in association with anterior wedging of the vertebral body below, with a characteristic triangular fragment arising from the antero-superior margin.

Lateral dislocations are also seen. High probability of neurological deficit

Question 26

What is Spondylosis?

Answer 26

Refers to degenerative changes of the intervertebral disc spaces, which is demonstrated by disc space narrowing, endplate sclerosis and osteophyte formation.

Facet joint OA is seen posteriorly. The associated osteophytes may impinge on the nerve root foramina.

Question 27

What is Paget’s disease?

Answer 27

The lumbar spine is often affected. There are three key features:

Bone is expanded
The cortex is thickened
The trabeculae is coarse

Question 28

What is Abdominal aortic aneurysm?

Answer 28

Patient usually present with back pain.

Demonstrated on either AP or lateral lumbar spine radiographs, if the aorta is calcified

Question 29

What is Ankylosing spondylitis?

Answer 29

Refers to calcification of the anterior and posterior longitudinal ligaments

Colcification of intervertebral discs resulting in fusion of the spine from the sacroiliac joints up through the thoracolumbar spine to the cervical spine.

“Bamboo spine”

Increases a patient chance of fracture.

Question 30

Spinal features