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Systematic review
Whenever you look at an adult elbow x-ray, review:
alignment
fat pads for effusion
bony cortex
Alignment
Check the anterior humeral line:
drawn down the anterior surface of the humerus
should intersect the middle 1/3 of the capitellum
if it does not, think: distal humeral fracture
Check the radiocapitellar line:
drawn along the radial neck
should always intersect the capitellum
-
if it does not, think: radial head dislocation or subluxation
check for an accompanying fracture, e.g. Monteggia fracture-dislocation
Effusion
Check for raised fat pads:
visible posterior fat pad always indicates an elbow effusion
visible anterior fat pad may be seen in normal patients and should only be thought of as an indicator of an elbow effusion when massively raised
if there is an effusion in an adult patient, think: acute intra-articular fracture and go looking for it
if a fracture cannot be identified but an effusion is present, think: undisplaced radial head fracture
Bone cortex
Check around every bone on the film
look specifically at areas of high-yield, e.g. radial head and neck and distal humerus
helps to find subtle injuries, e.g. coronoid process fracture or olecranon fracture
Common pathology
Radial head fracture
commonest adult elbow fracture; most frequently in women
mechanism: fall on abducted arm; direct blow uncommon
can be subtle and easily missed
Elbow dislocation
up to 25% of all adult elbow injuries; most frequently posterior
mechanism: fall onto extended arm
associated radial head fracture, coronoid process fracture, or both (‘terrible triad’)
Distal humeral fracture
common in elderly osteoporotic patients
mechanism: direct blow or fall on outstretched arm
typically intra-articular; unicondylar or bicondylar fractures
Olecranon fracture
common, represent 10% of all adult upper extremity fractures
mechanism: direct blow, fall on an outstretched hand with flexed elbow, avulsion fracture or stress fracture
typically widely displaced due to unopposed pull of triceps
Don't miss...
Coronoid process fracture
uncommon; often in association with dislocation
mechanism: fall onto extended arm
fragments involving >50% coronoid process are unstable
check for fractures on post-reduction films