x-ray anatomy shoulder Flashcards
reminder that in kids, there are 2 Lucent lines ( epiphyseal growth plates ) in the proximal humerus that can frequently be mistaken for fractures
what 2 locations can secondary ossification centres be found in the shoulder of kids
acromion and coracoid process
what is different about the ossification centre at the coracoid process and the acromion
the coracoid process ossification centre can be at the tip or the base
what are 3 things to look out for with suspicion of humeral fractures?
break to cortex
disruption to trabecular pattern
sclerosis (suggesting impact)
in paediatric skeleton, the proximal humeral metaphysics should be examined carefully for cortical disruption
if there is a shoulder injury due to high velocity, ensure to check clavicle, scapula, ribs, acromion and coracoid process
fractures of anterior lip of glenoid are VERY subtle and easily missed. Look carefully
how can you tell if the humeral head is anteriorly displaced from the glenohumeral joint
it gets displaced TOWARDS the coracoid process/ribs (down and in)
what 3 injuries are linked to anterior dislocation of the humeral head
- hill-sacks defect
- bankart lesion
- greater tuberosity
what is a hill sacks defect
dent/depression fracture to postero-lateral aspect of humeral head due to impact on front of glenoid
what is a bankart lesion
fracture of anterior lip of glenoid
how can you tell if the humeral head is displaced posteriorly
widening of joint space (>6mm) and is displaced laterally
(has light bulb shape as it is not internally rotated as usually)
displaced away from ribs
what is the normal acromioclavicular joint space in adults
7mm
if there is widening of the acromioclavicular joint space, what ligament is affected/ruptured
acromioclavicular ligament
how can you identify a coracoclavicular ligament rupture
the acromion and clavicle should be level BUT if there is rupture of the coracoclavicular ligament, the clavicle becomes slightly elevated causing a subluxation of the acromioclavicular joint.
what is a pseudo-dislocation as found in the shoulder joint?
blood in the joints can force inferior subluxation of the humeral head in the glenohumoral joint space
- not a true dislocation and usually caused by underlying fracture
what is rotator cuff athropathy
tear in the rotator cuff causes abnormal usage of shoulder joint which causes it to wear down and subsequently the humeral head migrates superiorly
- causes superior elevation of humeral head (reduced subacromial space) + erosions on inferior surface of acromion
- can cause impingement of suprespinatus tendon
- may occur in association with RA
What can indicate a benign/fluid filled bony lesion on a radiograph?
falling fragment sign
- cortical fragments from the fracture due to the lesion (cortical thinning), fall through the fluid filled lesion
