[MattSAU2XR8]

Bit late to the party, bit if I was you I'd definitely be looking for a surgical opinion.

Most (but not all) of our muscles and tendons have a necessary function and things don't work so well without them, and so the orthopedic surgeons usually say that if the tendon breaks the best solution is just to sew it back together...

Supraspinatus muscle runs outward across the top of the shoulder blade, and then the tendon (a continuation of the muscle) runs out across the shoulder joint, before heading down to attach to the outside of the humerus, or upper arm bone. So it functions to pull the arm up and into the socket that is the shoulder joint. Its main function is to stabilise the joint when the arm is elevated, eg. to 90 degrees or higher, and carrying a load, such as doing lat flys with dumbells, Although the joint will work better at all times if it is properly stabilised.

Counterintuitively, the humerus will tend to migrate upwards over time if supraspinatus isn't working, since the humeral head isn't held int he socket, and the humeral head will start to rub against the acromion (in effect an extension of the collar bone over the shoulder joint) and cause pain from rubbing in day to day activities.

And if left too long:
- The muscle will shrink away making repair difficult or impossible, and or
- Advanced age will make proper healing less likely

Ideally you want an opinion from a surgeon who specialises in shoulders, and since this is difficult for anyone who isn't an orthopedic surgeon to assess, a good starting point would be a surgeon who does shoulders for professional athletes.

I'd be wary of anyone who isn't a surgeon who says 'stay away from the knife' or similar. Because that's kind of like saying they wouldn't care if it was their muscle or tendon that was broken. And since they don't know how to fix it, its easy for them to criticise the surgeon.

Also, don't compare a complete tear to a partial tear. A partially torn tendon still works pretty much as well as a normal tendon unless it breaks completely. Kind of like an undersized tow rope vs a proper size one.

Or frozen shoulders, or nerve damage. All you have described is particular tendon that is completely torn, namely supraspinatus.