PCE axial skeleton

Question 1

All the bones of the face?

Answer 1

Frontal bone
Parietal bone
Temporal bone
Ethmoid bone
Sphenoid bone
Lacrimal bone
Zygomatic bone
Nasal bone
Vomer
Inferior nasal concha
Maxilla
Mandible

Question 2

Bony Anatomy Overview of the face

Answer 2

14 bones
12 made up of 6 pairs
Make up the upper and lower jaws, the nasal cavity, nasal septum and the orbits

Question 3

Frontal bones is classed as what?
Articulates with?
Where?

Answer 3

Classified as a FLAT bone

Forms the front of the Cranium above the orbits

Articulates with: Maxilla, Zygoma, Nasal, Lacrimal, Ethmoid and Sphenoid.

Question 4

Sphenoid bone
is classed as what?
Articulates with?
forms what?

Answer 4

Classified as an irregular bone

Forms part of the base of skull and lies between the frontal, temporal and occipital bones

Articulates with the Vomer, Ethmoid, occipital, frontal, zygomatic and palatine bones

Question 5

Temporal bone
is classed as what?
Articulates with?
forms what?

Answer 5

2 (left and right)

Classified as IRREGULAR bones

Articulates with the mandible, parietal bone, occipital bone, zygomatic bone and sphenoid bone

Has a Petrous part

Question 6

Ethmoid Bone
is classed as what?
Articulates with?
forms what?

Answer 6

Classified as an irregular bone

It lies between the orbits & anterior to the sphenoid

Forms part of the nasal cavity and medial wall of the orbits

Articulates with the vomer, maxillae, frontal, palatine, lacrimal & sphenoid bones.

Question 7

The Mandible
is classed as what?
Articulates with?
forms what?

Answer 7

Forms the lower jaw

Moveable bone

Primarily consists of a Ramus, Angle, Body and Symphysis

Forms part of the temporomandibular joint

Question 8

The Maxilla
is classed as what?
Articulates with?
forms what?

Answer 8

2 bones together form the upper jaw and orbital floor

Contains a sinus/antrum

upper teeth reside in the alveolar process of the maxilla

articulates with nine bones but seven of the face: the nasal, zygomatic, lacrimal, inferior nasal concha, palatine, vomer, and the adjacent maxilla

Question 9

Zygomatic Bones
overview

Answer 9

Pair of bones (Left and Right)

Form the palpable anterior part of the “cheekbones”

Zygomatic arch

Susceptible to fracture

Question 10

Lacrimal Bones
Where is it?
What does it contain?

Answer 10

Small bones that form part of the medial orbit

Contains the Lacrimal Sac and Nasolacrimal Canal/Duct

Question 11

Nasal Bones
overview

Answer 11

2 small bones

Form the bony base (bridge) of the nose

Support the cartilage

Often damaged when the nose is “broken”

Question 12

What are the Sinuses (Air-Filled Chambers) called?

Answer 12

Frontal sinus
Ethmoid sinus
Maxiallary sinus

Question 13

Assessing the Facial Bones
What is the search pattern?

Answer 13

Check for symmetry first
Lines of Dolan
or lines of McGrigor’s
Check the maxillary antra for fluid
Check the orbits for emphysema

Question 14

What is a tripod fracture?

Answer 14

A tripod fracture involves three or more parts of the face
the Zygoma
the Maxilla
the lateral border of the orbit (zygomaticofrontal suture)
Usually caused by a blow to the face

A classic fracture pattern of the face is the tripod fracture. It usually involves a combination of widening of the zygomaticofrontal suture, and fractures through the inferior orbital floor, the zygomatic arch and the lateral wall of the maxilla. Can involve all four but even then, we still call it a tripod fracture. Some texts will mention tetrapod fracture for this.

Question 15

What is a blowout fracture?

Answer 15

Direct blow to the eye/socket
Increases intra-orbital pressure
Fractures orbital floor
Soft tissues herniate through fracture

The blowout fracture. So this is where the patient receives a direct blow to the eyeball, squashing it into the orbital cavity. The orbital cavity is surrounded by bone so as the pressure increases from the impact, the eyeball has to go somewhere. With enough force, the orbital contents will break through the thinnest pieces of bones, this is found at the orbital floor or the medial wall of the orbit at the ethmoid bone. Once broken, the orbital contents, mainly the rectus muscles, can herniate through the opening and create what we call the teardrop sign.

Question 16

What is Orbital Emphysema (Black Eyebrow Sign)?

Answer 16

A black crescent of air is seen outlining the superior orbital margin
Indicates a fracture communicating with an air-filled chamber
Air enters the orbit
You may not see the fracture itself
Commonly involves the ethmoid sinuses

Following on from the tear drop sign we have supraorbital emphysema (black eyebrow sign). As we’ve seen blood can pool in the maxillary antrum which as we know is full of air. As the blood goes into the sinus, the air has to go somewhere and what can happen is it will migrate upwards until it sits in the upper most aspect of the orbital cavity. This can give the appearance of a black eyebrow on the image as we see here in the left orbit. It can also occur with an ethmoid fracture where you wont see blood in the sinus so can be the only sign of a fracture.

Question 17

What is Mucosal Thickening?

Answer 17

What is Mucosal Thickening?
Describe the differences. Not to be mistaken for a fluid level. A fluid level should be a fairly straight, flat line in the sinus. Mucosal thickening, tracts up the side of the sinus and tends to form a meniscus, having curved edges.

Question 18

What is the parasymphyseal region?

Answer 18

parasymphyseal region is that either side of the symphysis menti

Question 19

The condyle is the joint of the mandible (note slide)

Answer 19

The condyle is the joint of the mandible (note slide)

Question 20

Assessing the mandible overview

Answer 20

The mandible should be assessed as a ring structure
A break in one part of the ring should alert you to search for a second
Fractures extending to the roots of the teeth are open by definition
Check condyles and TMJ for fracture and dislocation/subluxation

It’s not very often that the mandible fractures in one place..

If the fractures extends to the dentitia (teeth) we call it an open fracture.

Question 21

slide 29 note slide PCE example
Open fracture of the left parasymphyseal region of the mandible
Fracture involving the base of the right condyle (sneaky one)

Answer 21

Open fracture of the left parasymphyseal region of the mandible
Fracture involving the base of the right condyle (sneaky one)

Question 22

Why is a PA mandible useful?

Answer 22

You can see a similar fracture pattern here on a PA mandible radiograph. Note the large soft tissue swelling.

The PA mandible can be very good at assessing the base of the condyles when performed well….the overlap on an OPG can make this a challenging area to assess. It can also help assess for degrees of displacement as well as being better at looking at the symphysis menti, which is often blurred on an OPG.

Question 23

TMJ Dislocation overview

Answer 23

Always anterior
Can be unilateral or bilateral
Usually present with a mouth fixed open after yawning

Question 24

Ligamentous Structures of the c spine?

Answer 24

This slide is a gentle reminder of the important ligamentous structures. Obviously, we cannot see these on the radiograph but they form an integral part of the 3-column theory

The anterior longitudinal ligament is a taut structure closely applied to the anterior aspect of the vertebral body in the teardrop fractures

Posterior longitudinal ligament is much weaker.

Ligamentum flavum is applied to the dorsal surface of the canal and is tightly applied to the lamina

Question 25

What does each column contain (three column theory)

Answer 25

This is Denis’s 3 columns, divided into posterior, middle and anterior.

*Anterior column –anterior portion of the vertebral body & associated soft structures

*Middle Column – posterior part of the vertebral body & associated soft tissue structures (Posterior longitudinal ligament)

The posterior column includes: -
▪ pedicles
▪ lamina
▪ facets
▪ ligamentum flavum
▪ spinous process
▪ posterior ligament complex (PLC)
Basically just the posterior elements.

Question 26

Are fractures involving the middle column stable or unstable?

Answer 26

Essentially, the middle column acts as a fulcrum or pivot point
What that means is that if there is compression (via flexion) at the anterior …so the vertebral bodies…we have to remember that there is a tension force being simultaneously applied posteriorly which can mean ligamentous rupture or further fracture.

Fractures NOT involving the middle column are considered stable
Fractures that DO involve the middle column and an adjacent column are unstable.

Question 27

Tools of Assessment for c spine

Answer 27

Vertebral alignment
Vertebral body heights
Intervertebral disc spaces
Posterior elements
Peg view
Pedicles
Associated soft tissues

Question 28

Lines of Assessment for c-spine?

Answer 28

1. Anterior margins of the vertebral bodies
2. Posterior margins of the vertebral bodies
3. Spinolaminar line

Question 29

The Pre-Vertebral Soft Tissues for c spine assessment how large can they be?

Answer 29

Superior soft tissues (red arrow) can be up to 1/2 vertebral body width

Inferior soft tissues (blue arrow) can be up to a whole vertebral body width

Question 30

Assessment Tools – The Harris Ring

Answer 30

Composite shadow made by superimposition of the lateral and posterior structures of C2

Usually always incomplete inferiorly

Anterior and posterior components should be complete

Can indicate a odontoid peg fracture or C2 body fracture
Pitfall - rotation may affect the appearance of the ring

Question 31

Assessment Tools – Body Heights & Intervertebral Discs

Answer 31

Body heights from C2 - C7 should be similar

Intervertebral disc spaces should be uniform

Assess all four aspects of the vertebral body visible on the lateral radiograph

Assess for retropulsion - denoted by the loss of the normal posterior concavity

Question 32

Assessing the Odontoid Peg

Answer 32

The lateral margins should align

The odontoid space should be symmetrical

Assess for ‘overhang’ of the lateral masses of C1 on C2

Question 33

Assessing the AP C-Spine

Answer 33

Should demonstrate C3 - C7

Spinous processes should be aligned

Sudden malalignment of the spinous processes may indicate a unilateral facet dislocation

The lateral ‘masses’ should be smooth and undulating

Pitfall - bifid spinous processes

Question 34

C1 – Jefferson Fracture overview

Answer 34

Usually secondary to an axial load/compression force

Force transmitted through the occipital condyles into the more delicate lateral masses of C1

Lateral masses driven outwards

The ‘atlas’ ring is fractured in multiple places

A Jefferson fracture, is a burst fracture of C1 and usually results from a blow to the top of the head - axial loading/compression force
Patients usually present with neck pain and unilateral occipital pain
The force is transmitted through the cranium and the occipital condyles and eventually to the superior surfaces of the lateral masses
The lateral masses are driven outwards resulting in bilateral fractures of the anterior and posterior arch of C1

Question 34

Odontoid Peg Fractures overview

Answer 34

Commonly secondary to hyperflexion
Allows for subluxation of C1 on C2
Requires surprisingly little force for fracture in an adult
May be visible on the lateral radiograph if there is subluxation/displacement
Best seen on the open mouth peg view (beware of the pitfalls)
Classified into three types

Question 35

Odontoid Peg Fractures types

Answer 35

Type 1 - Involve the tip of the peg (not to be confused with the apophysis in a paediatric patient-ossiculum terminale which fuses at 12ish). They are stable. Often these are oblique in orientation and associated with avulsion of the alar ligaments (which connects the tip of the peg to C1). These are rare.

Type 2 - Transverse fracture through the base. These are the most common and are considered unstable…

Type 3 - The fracture extends to involve the body of C2 and may communicate with the superior articulating facets. These are considered unstable.

Question 36

C2 – Hangman’s Fracture overview

Answer 36

Fracture through the pedicles

Split into three types depending on how much anterolisthesis and angulation of C2 on C3 has occurred.
Anterolisthesis being the forward slipping of one vertebra over another.

The fracture can present as a simple non-displaced fracture through the pedicles or more severely displaced with anterolisthesis of C2 on C3.

A large proportion have no neurological symptoms because the injury actually causes widening of the spinal canal….

Question 37

Flexion Teardrop Fracture overview

Answer 37

One of the most unstable of the cervical spine fractures is the flexion teardrop fracture

The Flexion mechanism causes crushing of the anterior vertebral body with a large triangular fragment that is pulled away by the ALL. So we get loss of anterior vertebral body height (key terminology)

The tension force posteriorly can rip through the posterior elements….and sometimes can then return to its normal position for the radiograph…..but you can see on the xray here that there is widening of the spinous processes.

These are very serious and usually result in spinal cord injury/compromise.

Question 38

Extension Teardrop Fracture overview

Answer 38

Look similar but not as serious as a flexion teardrop fracture
The triangular fragment is avulsed
The triangular fragment is smaller
Often no injury to the posterior elements
Not usually associated with spinal cord injury

Question 39

Clay Shoveler’s Fracture overview

Answer 39

A clay shoveler’s fracture, so called as when people shovelled clay it would stick to the shovel and when the would go to throw it over their shoulder, the inertia would pull the back, hyperextending their neck.

They are essentially avulsion fractures by the supraspinous ligament that presents as an isolated spinous process fracture usually C7 but can also be C6 or higher. Nower days they are still commonly caused by hyperflexion ( usually muscular contraction) but can also be caused by a direct blow to the spinous process. They are considered stable.

Question 40

Toolbox - The Lateral for lumbar spine

Answer 40

Check the alignment
Vertebral body heights should be equal
Intervertebral disc spaces should be uniform
Posterior body should be concave
Posterior elements should be intact

Question 41

Toolbox - The AP for lumbar and thoracic

Answer 41

Vertebral alignment - scoliosis
Pedicles intact?
Interpedicular distance should be uniform
Left paraspinal line should be follow the alignment
Right paraspinal line should be thinner/not always visible

Question 42

Toolbox - The Winking Owl

Answer 42

One pedicle missing
Produces a ‘winking owl’ sign
Commonly associated with metastatic deposits

It is fairly common practice to see ‘pedicles intact’ written in a normal spinal plain film report.

Question 43

Anterior Wedge Compression overview

Answer 43

Flexion and compression mechanism

Loss of anterior vertebral body height

Posterior height maintained

Greater than 50% - often requires further imaging

Assess for retropulsion

Unsurprisingly it is caused by a combination of a flexion and axial loading force, which results in compression or wedging of the anterior vertebral body. Crucially the posterior vertebral body remains normal.

They are most common in the thoracic spine but can affect the lumbar spine.

We tend to describe them simply as rough percentages i.e 25% (less than or greater than). Anything more than 50% anterior vertebral body height loss is usually assessed with further imaging to exclude posterior body height involvement.

Retropulsion is when a fracture fragment is displaced posteriorly. This is often not seen on plain film but should still be looked for as it may impinge on the spinal cord.

A way to word this may be: There is approximately 50% anterior vertebral body height loss of L1. Features are in keeping with an anterior wedge compression fracture.

Question 44

What is retropulsion?

Answer 44

Retropulsion is when the the posterior side of the vertebrata breaks and goes into the spinal canal. Its important to spot this on images as it affects the patient greatly.

Question 45

Burst fracture overview

Answer 45

Secondary to axial loading

2 or more columns

Neurologic compromise is common

Expect retropulsion

Increased interpedicular distance

Burst fractures tend to occur around the thoracolumbar junction, are secondary to an axial load force with high energy trauma and often involve 2 columns, so unstable.

They are more serious than an anterior wedge compression fracture.

Again, it may be subtle, but assess for retropulsion

The AP will reveal an increased interpedicular distance as the body is splayed horizontally. (Here you can see the marked bowing posteriorly, as well as anterior height loss. On the AP, we also see widening of the interpedicular distance)

Question 46

Osteoporotic Compression/Collapse

Answer 46

Most common vertebral fracture

Difficult to determine age

May result from low impact trauma

Can result in bi-concavity

Compare with previous imaging

Compression fractures related to osteoporosis are the most commonly occurring vertebral fracture you will see. In this case it is fairly easy to see the marked reduction in bone density however, it is not always this obvious.. The age of these fractures is nearly impossible to determine without previous imaging (which is always incredibly useful). Sometimes you end up with a bi-concavity to both endplates.

Some textbooks and websites discuss the possibility of being able to age fractures with plain film but I don’t feel any are robust enough to be definite. Notice that we can assess the Aorta here. Most commonly, I have seen subtle compression fractures at multiple levels with osteoporosis…which is another useful indicator. The same rules about column involvement apply.

Question 47

What are schmorl’s nodes?

Answer 47

Commonly Schmorl’s nodes are misinterpreted as an acute pathological finding. They are small focal depressions in the endplates…can be seen in both adjacent endplates…and their aetiology is uncertain. They are usually asymptomatic (although I have seen a couple of cases with what was thought to be associated back pain). You will see these fairly commonly and it is usually as an incidental finding.

Question 48

What are limbus vertebra?

Answer 48

Limbus vertebra are well corticated fragments (usually triangular) that occur during skeletal maturation as the nucleus pulposus herniates through the endplate and beneath the ring apophysis. They are most commonly seen at the anterosuperior aspect, rather than the inferoanterior aspect where we tend to see teardrop fractures.. All the ones I have seen have been visible at more than one level.

Question 49

Toolbox – Lines of Assessment for the pelvis

Answer 49

Iliopubic Line (Iliopectineal Line)
Ilioischial line
Shentons Line
Outline of Obturator Foramen
Symmetry of Sacroiliac joints – equal widths
Consistency of arcuate lines of the sacrum
Pubic symphysis
Outline of the Crests

Question 50

How to PCE a open book fracture

Answer 50

Open book fracture….a bit of a misnomer as technically there is no fracture…. But we do have marked diastasis (separation of normally joined structure without fracture) of the symphysis pubis and widening of both SIJs. Again…unstable.

Marked diastasis of the symphysis pubis and widening of both SIJs

Question 51

Avulsion Fractures in the pelvis overview slide 81

Answer 51

What attaches here? Sartorius runs from the ASIS to the medial aspect of the proximal tibia, it’s the longest muscle in the body

A sudden and tight contraction of this muscle can cause an avulsion….particularly if the muscles are well-developed in relation to the bone…like in an athletes….or a child…where the physis is weak in comparison to the ligaments and tendons.

Usually treated conservatively but depending on displacement (>2cm), the orthopaedic team may consider an ORIF. You can sometimes see a remodeling deformity at the asis where an old avulsion injury as healed over time.

Question 52

Acetabular fractures lines of assessment

Answer 52

The Acetabulum has two columns

Lines of assessment: -
Iliopubic (iliopectineal) line = Anterior Column
Ilioischial line = Posterior Column

2 column fractures are more likely to need surgery
Risk of secondary (post-traumatic) arthritis

Question 53

Pubic Rami Fractures overview

Answer 53

Common stable fracture of the pelvis

Usually as a result of a fall

Present with groin pain

Can be solitary fractures of the ischial ramus

Often involve both unilateral rami

Beware of the straddle injury!

Question 54

Straddle Fracture overview slide 91

Answer 54

I had to get this off the internet because they usually go straight to CT.

In this case the black arrow shows SIJ widening from the straddle fracture is the bilateral pubic rami fractures..

Unstable and serious fracture….often associated with bladder or urethral injuries.

Commonly associated with motorcyclist related RTC’s

Question 55

Metastatic disease on the pelvis radiographic appearance?

Answer 55

Metastatic disease on the pelvis as make the smooth cortex edge disappear almost, giving a fluffy cloudy appearance.

Question 56

What does anterolisthesis mean?

Answer 56

Anterolisthesis is an abnormal alignment of bones in the spine

It occurs when an upper vertebra slips forward on the one below, leading to pain and other symptoms.