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position of humerus in post shoulder dislocation
which part of the head hits which part of the fossa?
usually caused by what?
- post & IR
- ant hum head hits post glenoid
- convulsions, rarely by trauma
(often difficult to see in x-ray, so if it's suspected geta a CT or MRI)
shoulder dislocations, % that's ant, post, luxatio (inf)
- ant: 95-97%
- post: 2-4%
- luatio: 0.5%
common causes for unilateral AVN
uncommon causes for unilat AVN
bilat causes for AVN
- systemic problems...
- sickle cell
supraspinatus in MRI
- supraspinatus is the dark line under the arrows
- subscap is the dark chunk ant in the pic on the right
views of subscapularis
and in the pic on the right, the dark lines ant and post of the hum head are, left to right, supraspinatus, infraspinatus, teres minor
lat view of shoulder MRI, pic
he said you need to know that landmarks on this
which muscle is involved in RC tears most of the time?
- but can extend posteriorly to infraspinatus & teres minor
where do RC tears usually begin?
site of insertion
if subscap is involved in an RC tear, what is ti likely to look like, and what's associated with it?
- it'll be an isolated tear
- dislocation of biceps tendon
signs of RC tear - if you have all 3, or have 2 and yr over 60, 98% chance it's a RC tear
- supraspinatus wakness
- wakness in ER
(and >60 y/o, and night pain)
extrinsic mechanisms of RC tear injury
- repetitive microtrauma
- acute macrotrauma
- subacromial impingement
- glenohumeral instability
intrinsic causes of RC tear injury
- degeneration - tendinosis
- noninflammatory repetitive stress injury of tendon fibers
- not the same as tendonitis
radiographic findings for a chronic RC tear
- high riding humerus (decreased acromiohumeral distance - it'll be < 7 mm)
- faceting & sclerosis in inferolat acromion & sup aspect of greater tuberosity -- this'll present as increased radiodensity
- secondary osteophyotosis in GH joint to maintain joint congruity (the growth in the lower left side)
full thickness muscle tears - details and how they'll look
- fully extend from bursa to articular surface
- non-visualization of tendon
- fluid in expected location of tendon (so there'll be a black or white spot, I think usually white, depending on the type of MRI, where you want the tendon to be)
- measure AP width
- in the pic below the arrows point to fluid where tendon should be
a pic of calcific tendinosis (at the arrow)
- this is a plain x-ray
- shows deposition of calcium hydroxyapatite sup to greater tub at insertion of supraspinatus tendon
which tendon most commonly gets calcific tendinosis
what's happening in calcific tendinosis?
- it's mucoid degen of a tendon
- the tendon is thickened & heterogeneous w/o discrete defects
- can be subclinical to painful
what's the caclification going on in calcific tendinosis/
- calcium hydroxyapatite crystals
- visible on x-ray
- low signal intensity on all MRI sequences
how to treat calcific tendinosis?
injection of saline lavage
pic of biceps tendon subluxation where the subscap tendon continues across the biciptal groove as the transverse humeral lig, helping to stabilize the biceps tendon.
the arrow points ot a tear in subscap -- this lets the biceps tendon dislocate, usually medially
in this pic the biceps (b) is percedd on the lesser tuberosity (L)
pic of biceps tenosynovitis showing the biceps tendon sheath thickened by surrounding edema (arrows) with the deltoid (black) passing it on the left
a pic of subacromial subdeltoid bursitis -- arrosshow abnormal fluid deep to deltoid tendon