Shoulder Pain - Inflamed Supraspinatus?

[msk101]

Hi There,
If you've just woken up with this one day with no prior issues and fit and healthy i would also suggest you get your lower neck checked out on the same side as the sore arm. What you describe could be a result of a facet joint irritation (wry neck - from sleeping in an awkward position, stress etc) and could be irritating the nerve path from neck to elbow (hence why doing the movement with 90 degrees elbow flexion is more painful even though lever-arm is shorter and therefore should require less shoulder muscle effort than straight arm).

Gist of this is...get your lower cervical facet joints assessed and see if that's a limitation to your shoulder movements and referred pain as i find this is quite common with many physios and medicos forgetting to clear the neck as a source of symptoms in the arm and shoulder.

Let us know how you go.

Cheers,
msk101