What is rotator cuff tendinitis? What are the consequences of labeling it (perhaps incorrectly) as an "—itis"? What are the consequences of labeling rotator cuff tendinitis as "impingement syndrome"?
Rotator cuff tendinitis is not an inflammatory condition (as "itis" would suggest); it is a degenerative wearing out of the tendon, owing to repetitive use, poor blood supply and aging. It should be treated with an anti-inflammatory only to the extent that the anti-inflammatory medicine is also a pain reliever.
The supraspinatus tendon, as you see, has to make a bit of a turn before inserting on the humerus, which might impair perfusion to the insertion site
NORMAL SUPRASPINATUS ANATOMY
close up of the turn:
MRI VIEW (ok, I exaggerated the turn, but just a bit: it's NOT a straight shot)
There is no proof that anything is impinging (pressing) on the cuff
(C Neer, Penn Med '42, above, came up with this theory sans evidence and it stuck. By contrasy, a study found that there is no supporting evidence.
Accordingly, there is no evidence that we should surgically remove any "impinging" structures (though acromioplasty, the removal of "impinging" bone the acromion (and shown below), is among the most common operations we do) .
More troubling, perhaps, is that this is a question amenable to a randomized trial, yet such a study has not been done. Case series have shown that patients with no bone removal do as well as historical controls who did have bone resected.
The interested student is pointed to the best (and only; hence worst too) discussion of orthopaedic surgery semiotics and the pernicious effect of mis-naming things