Re: AC joint and possible distal clavicle resection
Sorry to hear that.
I had it done six years ago. I think its to make space so the tendons dont get inflamed. They might not see tears on an MRI or whatever but if they do the surgery they'd look for them & scar tissue (& repair if needed.)
In my case, I had arthritis on end of the collarbone. The way it was explained to me was, arthritis causes bone changes (spurs?) and that causes inflammation when the tendons have to move past it because they keep catching on the spur. When I fell on an outstretched arm playing baseball, a tiny little piece of bonespur was broken off or dislodged. They got rid of that and made more room, saw no tears, got rid of scar tissue on the subscap.
Anyway I loved the surgery - an hour later I was fine, no pain. That shoulder's fine (but I have the same arthritis in the other shoulder now so I have to be careful).