Hi - are you sure she is seeing a physio? 12-16 months MORE is unreasonable UNLESS she has "Wikipedia reference-linkfrozen shoulder".

Otherwise there is another diagnosis that has been missed.

It sounds like the physio and physician are guessing because Wikipedia reference-linkMRI has not been mentioned by you. As physio.irl mentions, it is best to get an MRI to see what is going on in there.

To give you an idea, i expect my patients to get better in 3-5 treatments over the course of 6 weeks. If i can't make a change in that time, then there is something there i don't know about (needs further scans etc) or it is something i can't help - it needs surgery. There are of course conditions which are clearly outlined which need more time than that but if it is really a muscular issue, it will respond in that time. I have a personal aim of helping first visit patients achieve 70% improvement after the first treatment.

All that is just to say that i would almost never recommend someone come to see me for 12-16 months to get better...

Good luck!

Get MRI and another opinion from a surgeon or another physio...