In this presentation we will discuss the basic of axial trauma from head to pelvis. We will discuss the important key points that aids in the diagnosis of axial trauma
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Trauma axial skeleton Dr. Muhammad Bin Zulfiqar
1. TRAUMA AXIAL SKELETON
DR MUHAMMAD BIN ZULFIQAR
PGR III FCPS Services institute of Medical Sciences/
Services Hospital Lahore
radiombz@gmail.com
Special thanks to Radiology master class
2. SKULL
• Bones and fractures
• X-rays are rarely indicated for detection of
skull fractures. If there is a history of sufficient
force to result in suspected fracture then CT is
usually required. CT is necessary to look for
underlying intracranial haemorrhage.
• Specific X-ray views are required to look for
foreign bodies in the scalp
3. • Normal skull - Lateral
• Anatomically the skull has inner and outer surfaces or
'tables'
• Skull X-rays show the course of vessels which indent the
inner table
• These vascular indentations branch and taper - whereas
fractures do not usually branch or taper
4. • Normal skull - AP
• Sutures have a saw-tooth appearance which distinguishes
them from fractures which form smooth lines
5. • Skull fractures - AP
• The black lines represent skull fractures
• These lines are too smooth to be sutures and do not branch like the vascular
markings of the skull
6. Basal skull fractures
• Fractures of the skull base are not readily
visible on plain X-rays. If injury to the skull
base is suspected clinically then CT is usually
indicated.
• Blood or cerebrospinal fluid (CSF) may leak
into the para-nasal sinuses following basal
skull fracture. In the context of trauma an
air/fluid level seen in the sphenoid sinus is
radiographic evidence of basal skull fracture.
7. • Sphenoid air-fluid level
• No fracture is visible
• The air-fluid level seen in the sphenoid sinus is due to
haemorrhage or CSF leakage due to basal skull fracture
• The other paranasal sinuses also contain blood due to
facial bone injury
8. • Skull - Depressed fracture
• Displaced or depressed skull fractures may result in
overlapping bone which causes white lines of increased
density
• Note: The sphenoid sinus is clear - however this does
not exclude a basal skull fracture
9. • Scalp foreign body X-ray
• To look for foreign bodies in the scalp specific radiographic settings
are required and the X-ray beam is aimed tangential to the area of
injury. It is therefore essential to specify that 'foreign body X-rays'
are required.
• Material that is not very dense, such as wood, will not show up on
X-ray. Good quality X-rays will show denser material such as glass.
• several foreign body fragments in the scalp - glass in this case
10. Systematic approach
• There are many complex overlapping bone
structures in the face with a highly variable
appearance. Radiological findings must be
related to clinical features as it is easy to
misinterpret appearances.
• Standard views
• Occipito-Mental (OM) and Occipito-Mental at
30 degrees angulation (OM30).
11. Key points
• Relate radiological appearances to clinical
features
• Follow the three 'McGrigor-Campbell' lines to
look for the common fracture patterns
• The most common fracture configurations are
- isolated zygomatic arch fracture - 'tripod'
fracture - and 'blowout' fracture
• Check for the 'teardrop' and 'eyebrow' signs
12. • Occipito-Mental (OM) view - Normal
• This view is acquired with the patient looking slightly upwards
• Each zygoma and zygomatic arch resembles the head and trunk of an elephant
• The blacker areas are the orbits and paranasal sinuses - frontal, nasal/ethmoid, and maxillary
• The frontal sinuses are highly variable in appearance
13. • Occipito-Mental (OM30) view - Normal
• This view is acquired at 30º from horizontal with the patient in the same
position as for the OM view
• Each infra-orbital canal is part of the floor of the orbit - these carry the
maxillary division of the trigeminal nerve which can be injured as the
result of fracture
• Note that each maxillary antrum is clear (black)
• Other visible structures include the mandible and the odontoid peg
14. • McGrigor-Campbell lines
• The ' McGrigor-Campbell lines' are visible on OM and OM30 views and can act as anatomical references to
assess the facial bones for injury
• Upper line - (Red) passes through the zygomatico-frontal sutures (asterisks) and across the upper edge of the
orbits
• Middle line - (Orange) follows the zygomatic arch (elephant's trunk), crosses the zygomatic bone and follows
the inferior orbital margins to the opposite side
• Lower line - (Green) passes through the condyle (1) and coronoid process (2) of the mandible and through the
lateral and medial walls of the maxillary antra on each side
• Midline - used to assess symmetry
15. • Isolated zygomatic arch fracture
• Disruption of the middle McGrigor-Campbell
line is due to a comminuted fracture of the
right zygomatic arch
• Following the upper and lower lines shows no
fracture
16. Tripod' fractures
• Trauma to the zygoma may result in impaction of the
whole bone into the maxillary antrum with fracture to
the orbital floor and lateral wall of the maxillary
antrum.
• The displaced zygoma is detached from the maxillary
bone, the inferior orbital rim, the frontal bone at the
zygomatico-frontal suture, and from the zygomatic
arch. The result is said to liken a 'tripod', but in reality
these fractures are often more complex than is
appreciated on plain X-ray. 'Quadripod' would perhaps
be a more accurate term as four fractures may be
visible.
17. • 'Tripod' fracture
• 1 - The zygoma (asterisk) is separated from the frontal
bone at the zygomatico-frontal suture
• 2 - Comminuted fracture of the zygomatic arch
• 3 - Orbital floor fracture
• 4 - Breach of the lateral wall of the maxillary antrum
18. • Maxillary antrum fluid level
• A fluid level of blood seen in the maxillary antrum may be the only obvious sign of fracture
• 'Tripod' fracture
• A - Widened zygomatico-frontal suture
• B - Zygomatic arch fracture
• C - Orbital floor fracture
• D - Lateral maxillary antrum wall fracture
19. Orbital 'blowout' fractures
• Trauma to the orbit may lead to increased
pressure in the orbit such that the thin bone
of the orbital floor bursts. This manifests as
the 'teardrop' sign which is due to herniation
of orbital contents into the maxillary antrum.
20. • Orbital 'blowout' fracture- Teardrop sign
• On the left a 'teardrop' of soft tissue has
herniated from the orbit into the maxillary
antrum
21. • Orbital emphysema
• Occasionally a 'tripod' or 'blowout' fracture will cause a leak of air from
the maxillary antrum into the orbit. This can have the appearance of a
dark 'eyebrow'.
• Orbital emphysema - 'Eyebrow' sign
• Fractures are visible of the lateral wall of the maxillary antrum and of the
orbital floor
• Air has leaked into the orbit and is seen as an area of comparative low
density - the 'eyebrow' sign
• There is also increased soft tissue density due to swelling, and increased
density of the maxillary antrum due to blood
22. • Fracture mimics
• X-ray appearances can easily be misinterpreted unless a systematic approach is
used to look for the common fracture patterns. Any suspected injury should be
correlated to the clinical features. Overlying structures such as sutures should not
be interpreted as fractures.
• The eye is drawn to the dark irregular line passing across the orbit which is the
normal coronal suture
• A systematic approach reveals a tripod injury with a large fracture of the orbital
floor
23. Mandible fractures
• The mandible can be considered as an
anatomical ring of bone, stabilised at each end
at the temporomandibular joints. A break of
the ring in one place will usually be
accompanied by further break in the ring
elsewhere. If you see one fracture, look for a
second fracture, or a dislocation of the
temporomandibular joint.
24. Orthopantomogram (OPG) and
Mandible views.
• Both views are necessary because fractures
are often only seen on one image. The OPG is
a panoramic view acquired with the camera
panning around the patient.
• Whenever one fracture is seen - check for a
second fracture or dislocation at the
temporomandibular joint
25. • Normal mandible -
Orthopantomogram
(OPG)
• Follow the cortical
edge all the way
around the mandible
• Check the
temporomandibular
joints
• Asterisks = Inferior
alveolar canal - the
course of the inferior
alveolar nerve
26. • OPG - Normal temporomandibular joint
• The condyle of the mandible meets the
glenoid fossa of the temporal bone to form
the temporomandibular joint (TMJ)
27. • Normal mandible - Mandibular view
• Follow the cortical edge all the way around
the mandible
28. • Mandible fracture - OPG
• (Same patient as image below)
• A fracture of the left mandible body is easy to see
• On the right the cortical outline is difficult to follow at
the base of the condyle (?) - but no second fracture is
readily seen
29. • Mandible fracture - Mandibular view
• (Same patient as image above)
• On this view the right condylar fracture is
more easily seen
30. Cervical spine - Normal anatomy
• Clinical considerations are particularly important in the
context of Cervical spine (C-spine) injury. This is because
normal C-spine X-rays cannot exclude significant injury, and
because a missed C-spine fracture can lead to death, or life
long neurological deficit.
• Clinico-radiological assessment of spinal injuries should be
managed by experienced clinicians in accordance with local
and national clinical guidelines. Imaging should not delay
resuscitation.
• Further imaging with CT or MRI (not discussed) is often
appropriate in the context of a high risk injury, neurological
deficit, limited clinical examination, or where there are
unclear X-ray findings.
31. Standard views
• The 3 standard views are - Lateral view - Anterior-Posterior
(AP) view - and the Odontoid Peg view (or Open Mouth
view). In the context of trauma these images are all difficult
to acquire because the patient may be in pain, confused,
unconscious, or unable to cooperate due to the
immobilisation devices.
• Additional views
• If the lateral view does not show the vertebrae down to T1
then a repeat view with the arms lowered or a 'Swimmer's
view' may be required.
• Lateral view
• The lateral view is often the most informative image.
Assessment requires a systematic approach.
32. Key points
• Normal C-spine X-rays do not exclude
significant injury
• Clinical considerations are of particular
importance when assessing appearances of C-
spine X-rays
• Look at all views available in a systematic
manner
34. • C-spine systematic approach - Normal Lateral 1
• Coverage - All vertebrae are visible from the skull base to
the top of T2 (T1 is considered adequate)
• - If T1 is not visible then a repeat image with the patient's
shoulders lowered or a 'swimmer's' view may be necessary
35. Approach
• Alignment - Check the Anterior line (the line of the anterior
longitudinal ligament), the Posterior line (the line of the
posterior longitudinal ligament), and the Spinolaminar line
(the line formed by the anterior edge of the spinous
processes - extends from inner edge of skull).
• - GREEN = Anterior line
• - ORANGE = Posterior line
• - RED = Spinolaminar line
• Bone - Trace the cortical outline of all the bones to check
for fractures
• Note: The spinal cord (not visible) lies between the
posterior and spinolaminar lines
36. • C-spine systematic approach - Normal Lateral 2
• Disc spaces - The vertebral bodies are spaced
apart by the intervertebral discs - not directly
visible with X-rays. These spaces should be
approximately equal in height
37. • Prevertebral soft tissue - Some fractures cause
widening of the prevertebral soft tissue due to
prevertebral haematoma
• - Normal prevertebral soft tissue (asterisks) -
narrow down to C4 and wider below
• - Above C4 ≤ 1/3rd vertebral body width
• - Below C4 ≤ 100% vertebral body width
• Note: Not all C-spine fractures are accompanied
by prevertebral haematoma - lack of prevertebral
soft tissue thickening should NOT be taken as
reassuring
• Edge of image - Check other visible structures
38. • C-spine normal anatomy - Lateral (detail)
• Bone - The cortical outline is not always well defined but forcing your eye
around the edge of all the bones will help you identify fractures
• C2 Bone Ring - At C2 (Axis) the lateral masses viewed side on form a ring of
corticated bone (red ring )
• This ring is not complete in all subjects and may appear as a double ring
• A fracture is sometimes seen as a step in the ring outline
39. • AP view
• Although often less informative than the lateral view this view may nevertheless
provide important corroborative information - a systematic approach is required.
40. Approach to C-spine
• C-spine systematic approach - Normal AP
• Coverage - The AP view should cover the whole C-spine and
the upper thoracic spine
• Alignment - The lateral edges of the C-spine are aligned
(red lines )
• Bone - Fractures are often less clearly visible on this view
than on the lateral
• Spacing - The spinous processes (orange) are in a straight
line and spaced approximately evenly
• Soft tissues - Check for surgical emphysema
• Edges of image - Check for injury to the upper ribs and the
lung apices for pneumothorax
41. Odontoid peg/Open mouth view
• Although called the 'odontoid peg' view the
odontoid peg is often obscured on this view by
overlapping structures such as the teeth or
occiput. Many refer to this view as the 'open
mouth' view. Its primary purpose is to view
lateral mass alignment.
• Even if a fracture of the odontoid peg is present it
is often not visible with this view. If a peg fracture
is not visible, but is suspected clinically by a
senior clinician, then further imaging with CT
should be considered.
42. • C-spine normal anatomy - Open mouth view
• This view is considered adequate if it shows the alignment
of the lateral processes of C1 and C2 (red circles)
• The distance between the peg and the lateral masses of C1
(asterisks) should be equal on each side
• Note: In this image the odontoid peg is fully visible which is
not often achievable in the context of trauma due to
difficulty in patient positioning
43. • Open mouth view - Rotated
• The distance between the peg and the lateral
processes is not equal - compare A (right) with B (left)
• This is because when the image was acquired the
patient's head was rotated to one side
• Alignment of the lateral processes can still be assessed
and is seen to be normal
44. 'Swimmer's' view
• This is an oblique view which projects the
humeral heads away from the C-spine. A
swimmer's view may be useful in assessing
alignment at the cervico-thoracic junction if
C7/T1 has not been adequately viewed on the
lateral image, or on a repeated lateral image with
the shoulders lowered.
• The view is difficult to achieve, and often difficult
to interpret. If plain X-ray imaging of the cervico-
thoracic junction is limited then CT may be
required.
45. • C-spine normal anatomy - ' Swimmer's' view
• Oblique image with the humeral heads projected away from the C-spine
• The cervico-thoracic junction can be seen
• Check alignment by carefully matching the corners of each adjacent vertebral body
- anteriorly and posteriorly
46. C1 fracture
• Injury to C1(atlas) results in loss of integrity of
its ring structure. The ring expands and loses
alignment with the adjacent occipital bone
above, and C2 below. This is most readily
appreciated on the open mouth view which
shows that the lateral masses of C1 no longer
align with the lateral masses of C2, and that
the spaces between the peg and the C1 lateral
masses are widened.
47. • C1 'Jefferson' fracture - Open mouth view
• The space between the odontoid peg of C2 and the
lateral masses of C1 is widened on both sides (arrows)
• The lateral masses of C1 are both laterally displaced
and no longer align with the lateral masses of C2 (red
rings)
48. • C2 fractures
• Fractures of C2 (axis) may involve the odontoid peg, vertebral body,
or the posterior elements.
• The C2 bone 'ring' is incomplete due to a fracture
• The odontoid peg is displaced posteriorly
49. • C2 odontoid peg
fracture - Open
mouth view
• Displaced fracture
of the odontoid
peg
• It is uncommon to
see such an
obvious fracture on
the open mouth
view - many
fractures of the
odontoid peg are
more readily seen
on the lateral view
50. • C2 'hangman' fracture
• The so called 'hangman' fracture results from a high force hyperextension
injury. The fracture involves the pedicles of C2 and often results in anterior
displacement of the body and peg of C2.
• Loss of alignment at C2/C3 with anterior displacement of C2 (large arrow)
• Following the cortical outline of C2 (white line) reveals discontinuity due
to a fracture
51. • 'Extension teardrop' fracture - Lateral view
• Hyperextension may result in avulsion of the anterior
corner of a vertebral body - most commonly C2. The
anterior longitudinal ligament remains attached to the
bone fragment which is separated from the vertebral body.
• A fracture fragment is seen at the anterior/inferior corner
of C2 resembling a 'teardrop'
52. • C-spine 'flexion teardrop' fracture
• This fracture may occur at any level between C3 and C7. It is a highly unstable
injury with a high incidence of associated spinal cord injury.
• Following the outline of the vertebral bodies shows an anterior - inferior C6
vertebral corner 'teardrop' fracture fragment
• The facet joint of C6/C7 is widened - compare with level above
•
53. • C-spine dislocation
injury
• It is possible to sustain
severe C-spine or spinal
cord injury without
evidence of a fracture.
Dislocations may be
transient with
spontaneous relocation
of the joints at the time
of injury. Occasionally
there may be locking or
'perching' of the facet
joints preventing the
bones from returning to
their normal positions.
This may be unilateral
or bilateral.
54. • Bilateral perched facets -
Lateral view
• (Same patient as image below)
• Loss of alignment of all three
lines at C5/C6 with 'perching'
of the C5 facet on the C6 facet
(ring)
• No fracture is visible
• The prevertebral soft tissue is
widened due to a haematoma
• Note
• The spinal canal lies between
the posterior (Orange) and
spinolaminar (Red) lines
• Derangement of the spinal
canal due to this injury results
in a high incidence of spinal
cord injury
55. • Bilateral perched facets - AP view
• (Same patient as image above)
• There is widening of space between the C5 and C6 spinous processes (SP) with loss
of normal alignment
• Again no fracture is demonstrated
56. • Pre-vertebral soft tissue
• At the level of C3 the prevertebral soft tissue is
thickened - ( >1/3rd the width of the vertebral body)
• This soft tissue swelling is the only visible sign of injury
• CT showed a fracture at C4 not visible on the plain X-
ray
• Note
• Not all C-spine fractures are accompanied by
prevertebral haematoma
• Lack of prevertebral soft tissue thickening should NOT
be taken as reassuring
57. • Pre-vertebral soft tissue
• Thickening of the pre-vertebral soft tissues is
occasionally the only X-ray sign of a C-spine
fracture.
58. • Spinous process 'clay-shoveller's' fracture
• Isolated fractures of the spinous processes are often difficult to identify, especially
at the cervico-thoracic junction where they may be obscured by overlying soft
tissues. A specific check is necessary of the cortical outline of each spinous process.
• These avulsion injuries are traditionally known as 'clay-shoveller's' fractures due to
the mechanism of repeated forceful flexion associated with shovelling.
59. Sternum
• Fractures of the sternum are often due to direct
trauma such as a road traffic crash, but may also
be caused by chest compressions in
cardiopulmonary resuscitation.
• Standard view
• Lateral - Sternal fractures are generally only
visible with a lateral view. In the context of
suspected sternal injury a chest X-ray is also
indicated. Severe chest trauma may require
further imaging with thoracic spine X-rays and/or
CT.
60. Key points
• Look for a step in the cortex of the sternum
• Don't mistake the sternomanubrial junction
for a fracture
61. Sternum - Normal - Lateral
• Note the normal sternomanubrial joint which
should not be mistaken for a fracture
62. • Sternal fractures
• Check for a step in the cortex of the sternum.
Swelling of the surrounding soft tissue can
accompany bone fracture.
• A step in the cortex of the sternum indicates a
fracture
63. Ribs
• Standard view
• Chest X-ray - A chest X-ray is not indicated for
suspected uncomplicated rib fractures. This is because
rib fractures are often undisplaced and therefore not
visualised, and, even if a fracture is visible,
management is unchanged. Rib fractures are often
seen as an incidental finding on X-rays of the chest,
shoulder or thoracic spine.
• If there has been trauma with a suspected
complications such as pneumothorax or haemothorax
then chest X-ray is indicated.
• Severe thoracic injury often requires CT examination.
64. Key points
• Chest X-ray is not indicated for suspected
uncomplicated rib fractures
• Chest X-ray is indicated for thoracic injury with
suspected complications
65. Rib fractures - Chest X-ray (detail)
• Multiple displaced lower left rib fractures are
visible
66. Subtle rib fracture - Shoulder X-ray
• The clavicle fracture is obvious
• A subtle rib fracture is also seen
• Note: Always check for a second injury
67. Rib fractures and chest pain
• Rib fractures are often found unexpectedly in
patients with chest pain as they may occur
without a clear history of trauma. Patients
treated with steroids may sustain a rib
fracture as the result of minor trauma, for
example on coughing.
68. Unexpected rib fracture - Shoulder X-ray
• This patient presented with no clear history of
trauma and complained of shoulder pain
• Shoulder examination was unremarkable
69. Complications of rib fractures
• If more than a simple rib fracture is suspected
then a chest X-ray may be indicated to look for
a pneumothorax or haemothorax.
• A chest X-ray alone cannot determine if a
pleural effusion is a haemothorax or simple
fluid , however in the context of significant
chest trauma this is often a reasonable
assumption.
70. • Rib fractures
with
haemothorax -
Chest X-ray
• Multiple rib
fractures are
accompanied by
a small pleural
effusion - likely a
haemothorax
71. • Rib fracture with pneumothorax - Chest X-ray
• A minimally displaced rib fracture is visible
• This fracture is complicated by a haemothorax and a pneumothorax with surgical emphysema
72. Thoracolumbar spine -
• Normal anatomy
• In the context of trauma similar principles apply to
imaging both the Thoracic spine (T-spine) and the
Lumbar spine (L-spine). The plain X-ray anatomy and
appearances of injuries to both these areas are
discussed together.
• In correct management of patients with spinal injury
may lead to, or exacerbate, neurological deficit.
Therefore patients with suspected spinal injury should
be managed by experienced clinicians in accordance
with local and national clinical guidelines. Imaging
should not delay resuscitation.
73. Thoracolumbar spine -
• Further imaging with CT or MRI (not discussed) is often
appropriate in the context of a high risk injury,
neurological deficit, limited clinical examination, or
where there are unclear X-ray findings.
• Good views of the T-spine and L-spine are difficult to
achieve in the context of trauma. Clinical assessment is
also often limited by distracting injuries or reduced
consciousness. The clinico-radiological assessment of
suspected T-spine or L-spine injuries therefore depends
on careful consideration of both the clinical and
radiological findings.
74. Key points
• Use a systematic approach
• Correlate radiological findings with the clinical
features
• If 'instability' is suspected then further
imaging with CT should be considered
• If you see one fracture - check for another
76. Thoracic spine - Standard views
• AP and Lateral - Assess both views
systematically (see box).
• Images of the thoracic and lumbar spine are
often large and the bones should be
scrutinized in detail (see images below).
• Note: The upper T-spine may not be visible on
the lateral view - if injury is suspected here
then a swimmer's view may be helpful.
77. • Thoracic spine systematic approach -
• Lateral and AP
• Coverage - The whole spine is visible
on both views
• Alignment - Follow the corners of the
vertebral bodies from one level to
the next
• Bones - The vertebral bodies should
gradually increase in size from top to
bottom
• Spacing - Disc spaces gradually
increase from superior to inferior -
Note: Due to magnification and spine
curvature the vertebral bodies and
discs at the edges of the image can
appear larger than those in the
centre of the image
• Soft tissues - Check the paravertebral
line (see AP image below)
• Edge of image - Check the other
structures visible
78. • Thoracic spine systematic approach -
• Lateral and AP
• Coverage - The whole spine is visible on
both views
• Alignment - Follow the corners of the
vertebral bodies from one level to the
next
• Bones - The vertebral bodies should
gradually increase in size from top to
bottom
• Spacing - Disc spaces gradually increase
from superior to inferior - Note: Due to
magnification and spine curvature the
vertebral bodies and discs at the edges
of the image can appear larger than
those in the centre of the image
• Soft tissues - Check the paravertebral
line (see AP image below)
• Edge of image - Check the other
structures visible
79. • T-spine normal anatomy - Lateral (detail)
• Alignment - Vertebral body alignment is assessed by carefully matching the
anterior and posterior corners of the vertebral bodies with the adjacent vertebra
• Bones - Gradual increase in vertebral body height from superior to inferior
• Spacing - Disc spaces gradually increase in height from superior to inferior
• VB = Vertebral body, P = Pedicle, SP = Spinous process (ribs overlying)
• F = Spinal nerve exit foramen
80. • T-spine normal anatomy - AP (detail)
• Alignment - The vertebral bodies and spinous processes (SP) are aligned
• Bones - The vertebral bodies and pedicles are intact
• Other visible bony structures include the transverse processes (TP), ribs, and the costovertebral and
costotransverse joints
• Spacing - Each disc space is of equal height when comparing left with right. The pedicles gradually
become wider apart from superior to inferior
• Soft tissue - Note the normal paravertebral soft tissue which forms a straight line on the left -
distinct from the aorta
81. Lumbar spine - Standard views
• AP and Lateral
• The whole L-spine should be viewed in both
views.
• Divergence of the X-ray beam may limit
assessment of the low lumbar spine levels - a
further 'coned lumbosacral view' centred at
the level of the lumbosacral junction may be
helpful.
82. • L-spine systematic approach -
Lateral
• Coverage - The whole L-spine
should be visible on both views
• Alignment - Follow the corners
of the vertebral bodies from one
level to the next (dotted lines)
• Bones - Follow the cortical
outline of each bone
• Spacing - Disc spaces gradually
increase in height from superior
to inferior - Note: The L5/S1
space is normally slightly
narrower than L4/L5
83. • L-spine systematic approach -
Lateral
• Coverage - The whole L-spine
should be visible on both views
• Alignment - Follow the corners of
the vertebral bodies from one
level to the next (dotted lines)
• Bones - Follow the cortical
outline of each bone
• Spacing - Disc spaces gradually
increase in height from superior
to inferior - Note: The L5/S1
space is normally slightly
narrower than L4/L5
84. • L-spine normal anatomy - Lateral (detail)
• Check the cortical outline of each vertebra
• The facet joints comprise the inferior and superior articular
processes of each adjacent level
• The pars interarticularis literally means 'part between the joints'
• P = Pedicle
• SP = Spinous process
85. • L-spine systematic approach -
Normal AP
• Alignment - The vertebral
bodies and spinous processes
are aligned
• Bones - The vertebral bodies
and pedicles are intact
• Spacing - Gradually increasing
disc height from superior to
inferior. The pedicles gradually
become wider apart from
superior to inferior - Note: The
lower discs are angled away
from the viewer and so are less
easily assessed on this view
86. L-spine normal anatomy - AP (detail)
• Check carefully for pedicle integrity and
transverse process fractures
87. Three column model
• The clinico-radiological assessment of thoracolumbar spine
stability is usually performed by spinal surgeons with the
help of radiologists.
• A simple model commonly used for assessment of spinal
stability is the 'three column' model. This states that if any
2 columns are injured then the injury is 'unstable'. This
theory is an over simplification if applied to plain X-rays
alone. It is important to be aware that some injuries are not
visible on X-ray and that 2 and 3 column injuries may be
underestimated as 1 or 2 column injuries respectively.
• If spinal instability is suspected on the basis of clinical or
radiological grounds then further imaging with CT should
be considered.
88. • Three column model - Anatomy
• Anterior column = Anterior half of the vertebral bodies and soft
tissues
• Middle column = Posterior half of the vertebral bodies and soft
tissues
• Posterior column = Posterior elements and soft soft tissues
89. • Three column model -
Fracture simulation
• Injuries 1 and 2 affect
one column only and
are considered 'stable'
• 1 - Spinous process
injury
• 2 - Anterior
compression injury
• Injuries 3 and 4 affect
two or more columns
and are considered
'unstable'
• 3 - 'Burst' fracture
• 4 - Flexion-distraction
fracture - 'Chance' type
injury
90. • Three column model
- Fracture simulation
• Injuries 1 and 2 affect
one column only and
are considered
'stable'
• 1 - Spinous process
injury
• 2 - Anterior
compression injury
• Injuries 3 and 4 affect
two or more columns
and are considered
'unstable'
• 3 - 'Burst' fracture
• 4 - Flexion-distraction
fracture - 'Chance'
type injury
91. Thoracolumbar spine
Injury classification
• The 'three column model' (see previous page) can be used to form a
basic classification of thoracolumbar spinal injuries (see box). This
page also discusses osteoporotic fractures, and fractures of the
transverse and spinous processes.
• Spinal injuries which are seen to disrupt structures of 2 or more
columns are considered 'unstable'. If the middle column is seen to
be injured it is usually taken that another column must be injured
even if no anterior or posterior column fracture is visible.
• If an injury is seen which disrupts 1 column then a second fracture
is also present in approximately 15% of cases. If a 2 column injury is
seen then likelihood of a second fracture increases to 40%.
• RULE: If you see one fracture - check for another
93. 1 Column - Anterior compression
injury
• Anterior compression injury is a common
fracture pattern which results from traumatic
hyper-flexion with compression. Although
considered 'stable' the greater the loss of
height anteriorly the greater the risk of middle
column involvement. X-ray may underestimate
the extent of injury and so if there has been
high risk injury or other suspicion of instability
then CT should be considered.
94. Anterior compression injury - L-spine - Lateral
• (Same patient as image below)
• A poorly defined dense (white) fracture line is visible
with a detached fracture fragment (asterisk)
• L1 has lost height anteriorly and there is disruption of
the anterior column only
95. Anterior compression injury - L-spine - AP
• (Same patient as image above)
• Loss of vertebral body height can be seen but
the fracture is not visible on this view
96. 2 column - 'Burst' fracture
• 'Burst' fractures result from high force vertical
compression trauma. Posterior displacement
of vertebral body fracture fragments into the
spinal canal leads to a high risk of spinal cord
or nerve root damage.
97. • Thoracolumbar 'Burst' fracture - Lateral
• (Same patient as image below)
• Both the anterior and middle columns are disrupted
• Injury has resulted in increased kyphosis
• A large vertebral body fragment is displaced anteriorly
98. • Thoracolumbar 'Burst' fracture - AP
• (Same patient as image above)
• The T12 vertebral body has lost height and the adjacent rib is fractured
• The interpedicular width should increase gradually from superior to inferior (white dotted lines)
• At the level of the fracture there is sudden widening of the interpedicular width - Note: This sign is not always
visible in burst fractures
• The normal paravertebral soft tissues (asterisks) is widened by a paraspinal haematoma at the level of the
fracture
99. 3 column - Flexion-distraction fracture
• Flexion-distraction injuries are associated with
high force deceleration injuries and are most
common at the thoracolumbar junction. Also
known as 'Chance-type' fractures (after the
radiologist who first described them) these
injuries are unstable and carry a high risk of
neurological deficit and abdominal organ injury.
• The 'fracture' line may pass through the disc
rather than the vertebral body, and so there may
not be visible bone injury of the anterior column.
100. • Flexion-distraction / 'Chance' fracture - Lateral
• All three columns are disrupted
• A = Widened spinous processes (SP) indicating
disruption of the interspinous ligaments at the level of
the fracture
• B = Normal interspinous distance
101. • Flexion-distraction / 'Chance' fracture - AP
• The interspinous distance is increased at the level
of the fracture
• In this case the pedicles and transverse processes
have been split horizontally
102. Osteoporotic 'insufficiency' injuries
• Thoracolumbar spine injuries are very
common in patients with osteoporosis.
Common fracture patterns include 'wedge'
injuries and 'biconcave' fractures.
103. • Thoracic spine - 'Wedge' compression fracture
• Note the low density (blackness) of the vertebral bodies
• The vertebral body has lost height anteriorly
• Kyphosis is increased
104. • Lumbar spine - Biconcave fracture
• Note the low density (blackness) of the vertebral bodies
• Compression injuries of both the superior and inferior endplates of
the vertebral body have resulted in a biconcave appearance
• The vertebral body has also lost height anteriorly - compare to level
below (superimposed dotted line)
105. Other fractures
• Spinal fractures may be isolated to the spinous
or transverse processes.
• Transverse process fractures are often not
visible with X-ray - (only seen on CT), and are
often associated with other fractures - so if
seen are a prompt to recheck all X-ray images
available and consider further imaging.
Transverse process fractures are also
associated with injury to the kidneys.
106. • Transverse process fracture - Lumbar spine
AP
• Multiple fractures of the transverse processes
are seen on one side
107. • Spinous process fracture - Lumbar spine -
Lateral
• Only 1 column is visibly injured but further
imaging should be considered
108. Sacrum and Pelvis
Anatomy
• The bony pelvis comprises the two hemi-pelvic
bones which are bound anteriorly at the pubic
symphysis and posteriorly at the sacroiliac joints.
• As with other anatomical bone rings if a fracture
is seen in one place a careful check should be
made for a second fracture, or for disruption of
the pubic symphysis or sacroiliac joints.
109. Key points
• If there is one pelvic fracture - look for
another fracture, or disruption of the pubic
symphysis or sacroiliac joints
• Carefully check the arcuate lines of the sacrum
110. • Pelvis anatomy -
Normal AP
• The 2 hemi-pelvis
bones and the sacrum
form a bone ring
bound posteriorly by
the sacroiliac joints
and anteriorly by the
pubic symphysis
• Each obturator
foramen is also
formed by a ring of
bone
111. • Hemi-pelvis anatomy -
Normal AP
• Each hemi-pelvis bone
comprises 3 bones - the
ilium (white), pubis
(orange) and ischium
(blue)
• The 3 bones fuse to form
the acetabulum - the
pelvic portion of the hip
joint
• ASIS = Anterior Superior
Iliac Spine = attachment
site for sartorius muscle
• AIIS = Anterior Inferior
Iliac Spine = attachment
site for rectus femoris
muscle
112. • Hemi-pelvis anatomy
- Normal AP
• Each hemi-pelvis bone
comprises 3 bones -
the ilium (white),
pubis (orange) and
ischium (blue)
• The 3 bones fuse to
form the acetabulum -
the pelvic portion of
the hip joint
• ASIS = Anterior
Superior Iliac Spine =
attachment site for
sartorius muscle
• AIIS = Anterior
Inferior Iliac Spine =
attachment site for
rectus femoris muscle
113. Pubic ramus fracture
• Fractures seen in the superior or inferior pubic
ramus are usually accompanied by another
fracture of the other ramus on the same side.
These are very common fractures in the
elderly.
114. • Pubic ramus
fracture
• The obturator ring
is incomplete on
the right
• A fracture passes
through the
superior and
inferior pubic rami
• Compare with the
normal left side
115. Pelvic fractures
• Fractures to the pelvis are highly variable in
appearance depending on the mechanism and
force of injury. Careful examination of the
cortical surfaces of the bony rings will reveal
most fractures.
• The extent of injury is often underestimated
on plain radiographs.
116. • Acetabular fracture
• A tiny step in the cortical edge of the pelvic ring
reveals a fracture which passes into the
acetabulum
• The fracture passes to the obturator ring and
then through the inferior pubic ramus
117. Pelvis diastasis
• High force injury to the bony pelvis may result
in "diastasis" (separation) at the pubic
symphysis or a sacroiliac joint.
118. • Pelvis diastasis
• Both the pubic symphysis and the right
sacroiliac joint are widened
• There is complete separation of the right
hemi-pelvis from the axial skeleton
119. • Avulsion injuries
• In young athletically active
individuals avulsion injuries may
occur, most frequently at the
ASIS, and occasionally at the
AIIS.
• ASIS (anterior superior iliac
spine) avulsion fracture
• A small fragment of bone has
detached from the pelvis
• All or part of the sartorius
tendon origin will be attached to
the bone fragment
• Note the normal appearance of
the unfused iliac crest apophysis
in this male teenager
120. Sacral injuries
• Fractures of the sacrum may be isolated or
accompany pelvis fractures. They are easily
missed unless a specific check of the arcuate
lines is made on every pelvic X-ray.
121. • Pelvis anatomy - Sacrum - Normal AP
• The sacrum and the iliac bones overlap to
form the sacroiliac joints
• The arcuate lines of the sacrum are the roofs
of the sacral exit foramina which carry the
sacral nerve roots
122. • Sacral fracture- AP pelvis
• Loss of the smooth arcuate lines is a sign of
sacral fracture