Inferior displacement of distal component
Clavicle fracture typically leads to what displacement?
Malalignment of clavicle and acromion
Inferior displacement of acromion
How are abnormalities of the acromioclavicular joint determined?
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Coracoclavicular ligaments
What ligaments tend to tear in acromio-clavicular displacement?
AP view (other views include “Y view”, or axial view)
The thin ring on the medial side of the humeral head is the glenoid fossa – the medial part of the humerus should sit neatly in it, as in the image
How should a normal glenohumoral joint appear?
Glenoid and humeral head surfaces malaligned
Humeral head not overlapping with (instead sits below) the coracoid process
What two things will you look for on limb X ray in glenohumeral dislocation?
Widened glenohumeral joint
Light bulb sign
Again, no overlap with coracoid
“Shoulder pain following epileptic fit”
What will make you suspect a posterior humaral dislocation on X ray?
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Surgical neck.
Tends to be transverse fracture at the neck, along with separation of the greater tubercle from the head (seen)
What is the most common site of humeral fracture?
In bone pathology (e.g. multiple myeloma, osteosarcoma)
Note the lytic lesion in the image
When do shaft fractures of the humerus tend to occur?
CRITOL – develop from 6-12 years and fuse in early adulthood
Capitulum
Radial head
Internal epicondyle
Trochlea
Olecranon
Lateral epicondyle
What is the order in which parts of the elbow ossify?
Anterior fat pad
Anterior humerus line
Radiocapitellar line
What are some of the features of a normal lateral elbow x ray in a 7 year old?
Joint effusion, often due to hemiarthrosis from fracture. Note the posterior fat pad is also visible – this is always abnormal
No other signs of fracture, but a consistent Hx, would indicate a radial head fracture (seen) or a supracondylar fracture (children)
What does the raised fat pad sign indicate?
Non-traumatic cause of effusion – inflammatory condition, septic joint, etc
What does the raised fat pad sign in the absence of trauma history indicate?
Less than 1/3rd of capitulum lies behind the anterior humerus line
What X ray features may indicate a supracondylar fracture?
Radiocapitellar line does not pass through capitulum
How is radial head dislocation identified?
Elderly – Colle’s type, based on osteopenia
Children – Greenstick
What forearm fractures might you be expecting in different age groups?
Transverse fracture of distal radius leading to dorsal displacement and angulation of the wrist – dinner fork deformity
What is a Colle’s fracture?
Opposite of a Colle’s:
Transverse fracture of radius with palmar displacement and angulation of the wrist
(note the significant soft-tissue swelling)
What is a Reverse-Colle’s fracture/Smith’s fracture?
Features of this X ray:
Lateral displacement of ulnar styloid process (AP)
Dorsal displacement of carpals and hand on lateral view
What might a comminuted fracture of the distal forearm appear like?
Both are bound together by an interosseous ligament running their length. If one breaks, the ligament forces the other out of its socket at its weakest point (usually the elbow)
(note loss of radiocapitellar line)
Describe how an ulnar fracture leads to radial dislocation, and vica versa
Torus injury has buckling without fracture
Greenstick has partial fracture, usually with buckling (seen)
Both happen usually only in children due to their bone flexibility
Distinguish between a Torus injury and Greenstick fracture
To assess the radius, capitate and lunate line up together
Why is a lateral view essential in suspected wrist fractures?
Scaphoid
Post-traumatic wrist pain with snuff box tenderness
What is the most commonly fractures carpal, and when is X ray indicated to search for it?
When you suspect it:
30% do not show up on X ray, but can still have significant sequellae (e.g. AVN)
When do you treat scaphoid fracture?
Lateral
(note the fracture is only the little piece that has come off)
Triquetrium fracture can only be seen on what view?
When nothing has come up on the usual (AP and lateral) views or you suspect Hamate fracture
(hint – upper right carpal)
When might you order an oblique view hand x ray?
Non-uniform distance between all of them
(normal seen)
What radiographic signs indicate that the carpals may have a dislocation or fracture?
Scapholunate ligament – leads to widening (>2mm) of this joint on ulnar deviation view
What is the most commonly damaged carpal ligament?
Lunate
(note the half-moon lunate is different on each)
What bone do the most common wrist dislocations involve?
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Unbroken shenton’s line
Taken in AP or lateral positions
Intact cortex of femur
What are the features of a normal hip X-ray?
Intracapsular – subcapital, transcervical, basicervical
Extracapsular – intertrochanteric, subtrochanteric
How are proximal femoral fractures classified?
Shenton’s line is disrupted
Increased opacity of femoral neck (density rise due to impactation)
Lesser trochanter more prominant (due to external rotation)
What are the X ray features of a Subcapital Femoral Fracture?
Assessing severity of femoral neck fractures
What is the Garden classification?
Fracture runs between trochanters
Often comminution with lesser trochanter
Does not involve femoral neck
What are the features of an intertrochanteric fracture?
Fracture is distal to the trochanters
Femoral neck intact
What are the features of a subtrochanteric fracture on X ray?
Post-Total hip replacement (although not this image)
Usually posterior
May be associated with acetabular fracture or soft tissue injury
When is hip dislocation most common, and in what direction does it usually occur?
High impact collision (road accident)
Pathological fracture
What are the two main causes of femoral shaft fracture?
What are the normal findings on an AP knee X ray?
Note – widening of the fat pads superficial and deep to the suprapatellar pouch can be indicative of knee joint effusion
What are the normal findings on a lateral knee X ray?
Assessing osteoarthritis of the pallatofemoral compartment
When is a Skyline view of the knee indicated?
Displacement of the plateau
Here, the lateral plateau is shifted down and out: should line up almost fully with the femur above
What are some signs of tibial plateau fracture on X ray?
Note increased density surrounding the fat pads – indicates joint effusion due to blood leakage
How might a patellar fracture appear on X ray?
Fabella – normal sesamoid bone at lateral head of gastrocnemius tendon
Bipartite patella area – patellar is in two pieces
What are some normal variants of knee anatomy sometimes seen on X ray?
Stress fracture
Toddler spiral fracture (often presents with refusal to weight bear and no displacement; seen)
Most tibial fractures result from high force impact, but some may be more subtle. Which ones might be more subtle, or might not show on X ray initially?
Periosteal thicking
Region of increased density
What will a tibial stress fracture look like?
Ankle mortise
What view should be done of suspected ankle fractures?
Tibia, fibula and talus
Distal tibiofibular syndesmosis
Lateral and medial ligaments (attach talus to lateral and medial malleolus)
What are the main bones and ligaments which may be injured during an ankle fracture?
Based on their position relative to distal tibio-fibular syndesmosis
Weber A – Distal to ankle joint
Weber B – At level of ankle joint
Weber C – above ankle joint
How are lateral (fibular) malleolar fractures classified?
Transverse medial malleolus fracture
Lateral malleolus fracture (usually Weber B)
Medial widening of the joint due to displacement of the talus
What are the features of a bimalleolar ankle fracture?
Medial malleolus fracture
Lateral malleolus fracture (usually Weber C)
Posterior malleolus fracture (the very thin line in the tibia, around the level of the fibula fracture)
Anteriorly widened and unstable joint
Posterio-lateral displacement of the tallus (with the medial and lateral malleolus bone fragments)
What are the features of a trimalleolar fracture?
Disruption of medial ankle joint with a small bone avulsion
Disruption of the distal tiobio-fibular syndesmosis
Proximal (and not distal) fibular fracture
What are the features of a Maisonneuvre fracture?
Calcaneal fractures
Axial loading fractures of the spine
What fractures tend to be associated with falling from height?
Lateral and Axial
What are the standard views for a calcaneal fracture?
28-40 degrees
What is Boher’s angle?
Flattening of Boher’s angle
Non-intact cortex of calcaneous/loss of smooth cortical edge
Depression of the articular surface
(remember, X rays of calcaneous normally underestimate the severity of a fracture: based on the articular surface, this one is a shocker)
What are the X ray signs of calcaneal fracture?
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Dislocation or fracture at the temperomandibular joint
If a fracture is identified at the mandible, what must you further check for?
Orthopantomogram
What is the normal X ray view for examining the mandible?
Loss of smoothness in the cortical edge of the mandible
(note – compare the right and left temperalmandibular joints – difference seen in mandibles. Unclear whether fracture, but possible)
What sign might be present in mandibular fracture?
Mandibular view
(image is of the same patient as last question; easier to see that there is a fracture of the mandibular condyle)
What view may help if you are unsure if there is a fracture near the temperomandibular joint?
Lateral
AP
Odontoid Peg View (Open mouth)
+/- Swimmers view if T1 not visible – arm up (Seen)
What are the three views used for C spine injuries?
To view the odontoid peg
Note – lateral masses of C1 and C2 should have an equal distance between them, and the odontoid peg, on both sides
What is the Open mouth view done for?
High risk injury
Neurological deficit
Limited clinical examination
Unclear X ray findings
(Note – (-) X ray does NOT exclude pathology in C spine injury)
When is CT or MRI indicated in the context of C spine injury?
CABSSE
Coverage – Adequate
Alignment – Of anterior, posterior and spinolaminar lines
Bones – Cortical outline and vertebral body height
Spacing – Discs/spinous processes
Soft tissue – Pre-vertebral
Edge of image
What is the systematic approach to assessing C Spine injury?
Narrow to C4, then widens
Above C4 – ~30% of body width
C4 – C7 – ~100% vertebral body width
What are the soft tissue findings you expect in a normal C spine X ray?
C2
(fractures can sometimes be seen as a step in the ring outline, although the ring is not complete in all normal patients)
Where do you expect to see a corticated ring on spinal X ray?
Loss of integrity of its ring structure
Lateral masses of C1 no longer have equal distances to the Odontoid Peg
What Xray features will likely occur in fracture of C1?
C2 bone ring (red) becomes incomplete
Odontoid peg is displaced (also can be seen in open mouth view)
What Xray features can occur in a fracture of C2?
High force hyperextension injury leading to fracture of C2
Shows loss of alignment on Xray, and discontinuity of cortical outline of C2
What is a hangman fracture?
“Extension Teardrop” fracture
Anterior, inferior part of C2 fractures off, leaving a ‘teardrop’
Aside from hangman injury, what fracture can occur as a result of extension of the neck?
C3-7 – highly unstable w/ high incidence of associated spinal injury
X ray features include ‘teardrop’ (similar to C2 extension teardrop injury’) and widened facet joint space between C6 and 7
At what vertebral levels do flexion teardrop fractures usually occur?
Loss of alignment with a vertebral facet perched on top of another one (in this case, C5 and 6)
AP view will show much larger space between spinous processes
No fracture seen
High incidence of spinal injury
What might you see in bilateral perched facets, and what is the cause?
Fracture. Should be around 30%. Do CT
What would soft tissue in front of C3, 50% the size of the vertebral body maybe indicate, assuming everything else is normal?
Broken spinous process
How will a “clay-shoveler’s” fracture show?
Lateral
What view is required in sternal fracture?
Look for discontinuity of the cortex
How do you identify a sternal fracture?
If there are suspected complications – haemothorax, pneumothorax or pulmonary contusion
When is a CXR indicated in the context of rib fracture?
Find the pathologies:
Hint – they are on the RHS, and there are three separate major categories of pathology
What might the CXR of a patient who has sustained rib fracture appear like if complications develop?
CABSSE
Coverage – check it has T1-T12, and L1-L5 if lumbar
Alignment
Bones – body size should gradually increase from top to bottom
Spacing – (note, spaces at top and bottom of X ray can appear larger due to spine curvature and X ray physics)
Soft-tissues – paravertebral line
Edge of image
What is the best systematic approach to assessing thoracic and lumbar spine xrays?
If it affects only one column, it is probably stable (e.g. spinous process fracture, anterior vertebral body compression fracture)
If it affects more than one column, it is probably unstable (e.g. total vertebral body compression fracture)
What is the three column model of spinal fractures?
In spinal injuries – 1 column fracture has 15% chance of another fracture being found somewhere. 2 column fracture has 40% chance
Why must you always assess for other fractures if you find one?
Loss of body height
What features will you expect on compression fracture of the spine?
Anterior and middle column disruption
Vertebral body fragmentation (this one has a large anterior fragment)
Widening of the pedicles on AP (all pedicles should line up nicely)
What features might you expect on a burst fracture?
Thoracolumbar junction – mostly due to high force deceleration
Highly unstable and risk of neuro damage
Where are flexion-distraction injuries most common?
All 3 columns disrupted
Widened spinous processes space – indicates disruption of interspinous ligaments
Normal interspinous distance
What xray features are seen in flexion-distraction injuries?
Crush fracture of a vertebral body so bad, it looks like a wedge
(note the increased kyphosis and low density vertebrae)
What is a wedge injury in a patient with osteoporosis?
Compression fracture to both the superior and inferior parts of a vertebrae – makes it biconcave. Also height loss
What is a biconcave injury in a patient with osteoporosis?
NOTE SPINOUS PROCESS FRACTURES NOT COVERED. HOPING THEY WILL BE OBVIOUS ENOUGH. ONLY AFFECT ONE COLUMN
Incomplete cortex
How should you try to identify pelvic fractures?
Where is the fracture on this image?
Pubic symphysis and sacroiliac joints are widened
What are the signs of pelvic diastasis (separation)?
ASIS – usually in young, athletic individuals
What is the most common site of pelvic avulsion injury?
Loss of arcuate lines
(note – left is fractures, right is normal)
What is a sign of sacral fracture?
