How might you distinguish a subacromial bursitis from a supraspinatus tendinitis?
According to textbooks the distinction is made by assessing resisted motion. While you press the patient’s elbow firmly against the trunk, ask him or her to try and abduct the arm while you prevent any movement. If the manoeuvre causes pain, it is supposed to indicate the presence of a supraspinatus tendinitis. In fact, the test is quite non-specific and cannot reliably distinguish subacromial bursitis from supraspinatus tendinitis. Since the treatment of both these conditions is similar, the issue is academic.
