You need to find a very good orthopedic surgeon. I happened to get lucky and got a very, very good one. He looked at my MRI and said, "This is work-related, no question." My comp advocate said that that doctor had gone to court enough that no one argued with him anymore. The company doctor was going over my case, I was answering questions, got to the part where my doctor said I needed surgery and he asked me to repeat the name. I did. The interview/exam was over. He concurred with my doc and I had surgery on both shoulders.
Follow the PT exactly. It will be powerfully tempting to overdo it. Don't. Overdoing it leads to frozen shoulder, you DO NOT want that. That was the most horrible part. I had to have a crying towel while the PT chick broke up the scar tissue.
When you are getting stronger, ask your PT peeps if they have a work hardening program. You're going to be off for a while and work hardening will make coming back easier.