Subdeltoid bursitis or supraspinatus tendinosis ?
How do we distinguish a chronic subdeltoid bursitis from a tendinosis ?
The clinical image of a chronic subdeltoid bursitis and a supraspinatus tendinosis could be quite similar. In fact this is not very surprising since both structures are anatomically closely connected, so the one can easily affect the other.
In both cases some passive movements may be painful end range and some resisted tests (abduction in case of a supraspinatus problem ; lateral rotation in case of a infraspinatus problem).
Solution : repeat the resisted tests from a lying position and compare with the test result found in the standing position ; we could also perform resisted tests with some traction built in at the arm.
So, if a resisted test in standing is positive, but in lying it becomes negative, or it improves, we don't think of a contractile lesion anymore, but we think of compression on an inert structure, in that case the subdeltoid bursa.
In case of a real tendinitis or tendinosis, resisted tests will be positive regardless from the starting position of the test.