I dislocated my shoulder lifting some cinder blocks that were too heavy for me. The emergency room doctor put the arm back in the socket. I was fine for about six months. Then I dislocated it again. When I went to the orthopedic surgeon, he put me face up on a table. I could hardly stand it when he moved my arm out to the side. The elbow was bent and my palm was facing the ceiling. When he put pressure down through the shoulder itself, it felt much better. What does this test show?

It sounds like you are describing a test called the relocation test. This is a test of shoulder instability. When positive, the first position (arm out to the side, palm up) causes the patient extreme anxiety or fear that the arm is going to dislocate again.

Downward pressure against the head of the humerus in this position prevents partial dislocation called subluxation or full dislocation. This test actually stabilizes the joint. It feels better because the humeral head is pushed back into the socket.

The doctor uses this test along with several others to tell 1) is the joint stable and 2) if not, how loose or unstable is it? Sometimes patients have pain with this test but no apprehension. That is not as diagnostic as the patient who has apprehension and pain at the same time.