What is the approx. percentage likelihood in your practice experience that a cortisone injection will significantly reduce shoulder impingement pain?

80-90 %: In my experience if you have a definite diagnosis of impingement syndrome(made by history, physical exam and confirmed by a good mri)your chances of improvement after a lidocaine/marcaine/steroid injection that is in your subacromial space(best done by ors) is 80-90%. In fact, if someone w/'impingement'does not get better after injection than the diagnosis may be incorrect or misplaced injection.