X-rays and the Upper Limbs Flashcards
Why is one x-ray view sometimes not enough to visualise a fracture?
Fractures may be invisible, alignment cant be fully assessed
What is normally the best number of x-ray views to be taken?
Two views
What are some examples of when more than two x-ray views are needed?
Cervical spine = AP, lateral and odontoid peg needed
Scaphoid = AP, lateral and two obliques needed
What are some ways fractures can appear on x-rays?
Lucency crossing bones, cortical expansion, spiral/transverse, comminution, joint involvement, angulation, displacement, impaction, avulsion
What are some bony entities which superficially resemble acute avulsion fractures?
Sesamoid bones, accessory ossification centres and old non-united fractures
How can you tell acute avulsion fractures apart from their mimics?
Avulsion fracture fragments are incompletely corticated = all mimics have a completely corticated contour
What are some joints that can be used to assess bony alignment?
Acromioclavicular, glenohumeral , elbow (radio-capitellar and humero-capitellar), lateral wrist
Where may fat density be seen on a normal x-ray?
Anterior to the distal humerus
What is the posterior fat pad sign?
Visible posterior fat pad = indicates elbow trauma which has caused an effusion
How are children’s bones different form adult bones?
They are soft so “bend and bow” rather than £snap and splinter” = buckle fracture, plastic bowing
Fractures are often incomplete = greenstick fracture
What is it common for ligaments and tendons in children to do?
Avulse their soft bony attachments
How may a physis appear on an x-ray?
Lucency between the epiphysis and metaphysis = may look like a fracture
Why is the physis prone to injury?
It is the weakest part of developing bone
Where is the epiphysis always seen on normal x-rays?
Always centred on the metaphysis
What kind of fractures are Salter-Harris fractures?
Growth plate (physis) fractures
What may be an indication of a non-accidental injury (NAI)?
An injury that doesn’t fit with the carers description of the history
Why do bones and joints form rings?
To help share the transmission of force and increase strength (e.g spinal canal, pelvis)
Why should you expect at least two disruptions when a bony ring is injured?
Its difficult to disrupt a ring in only one place (some disruptions may be fractures and others dislocations)
What foreign objects may be seen on an x-ray?
Dense objects = metal and glass
Plastic and wood are often invisible
When should you suspect a pathological fracture?
When the bone abnormality seems out of proportion to the mechanism of injury
What are pathological fractures typically a result of?
Normal stresses on a weakened skeleton
What are some examples of pathological fractures?
Colles fracture, radial buckle fracture, scaphoid fracture and surgical neck of humerus fracture
What are some features of a Colles fracture?
Occur in elderly with osteoporosis, dorsal angulation of the radius, associated with ulnar styloid fracture
What are some features of a radial buckle fracture?
Occurs in children with soft bones, only half of them are visible
What are some features of a scaphoid fracture?
Occurs in relatively young men, pain in anatomical snuffbox, commonly occurs mid-scaphoid
What are some features of a surgical neck of humerus fracture?
Occurs in post menopausal females, sclerosis indicates impaction, often comminuted, can damage axillary nerve
What are some commonly missed upper limb injuries?
Posterior shoulder dislocation, supracondylar fracture, scaphoid fracture, Bennet’s fracture
How should a posterior shoulder dislocation be imaged?
Oblique view should always be obtained = shows humeral head lies posterior to the articular surface of the glenoid
Why are AP views not suitable for imaging a posterior shoulder dislocation?
Lack of displacement makes it difficult to appreciate
What are some features of a supracondylar fracture?
Found be assessing the humero-capitellar alignment
Has visible posterior fat pad
Can damage brachial artery acutely and will malunite if untreated
How should a scaphoid fracture be imaged?
Can be invisible despite multiple views
Repeat the x-ray after 10 days and MRI can be useful in confirming/excluding a fracture
What may a scaphoid fracture cause?
Proximal scaphoid blood supply can be disrupted, making it prone to non-union and avascular necrosis = may cause early wrist osteoarthritis
What is involved in a Bennett’s fracture?
Articular surface of wrist of first metacarpal base
What may a Bennett’s fracture lead to?
Tendons pulling on the thumb distal to the fracture causes displacement = can lead to deformity, dysfunction and osteoarthritis
