I take it PRP or prolotherapy hasn't been mentioned.
PRP healed a full thickness tear of my supraspinatus tendon. Took a while, had to have a couple of fat grafts, will never be perfect, but it was a full thickness tear that healed without surgery. You jump on tendon problems early, before they get as severe as mine was, you can totally repair them -- with the right doc.
Read posts 28,37,38,39.
PRP (which I have had) for tendonosis (not a tear) is pretty much a waste of money. Meaning for double the money for a treatment it takes up to 6 weeks to really reap its benefits. And for tendonosis, regular prolo with a dextrose/water based test suspension/lido mix is far superior in results. I have had prolo in the forms of PRP, Dextrose, Sodium morrhuate, Dextrose/test suspension mix. Nothing comes close to the last one in regards to results when it does not involve a tear.
For any sort of tear PRP is the obvious choice. But I doubt it would benefit the OP as much as other prolo methods.