Insurance companies will force you to go through traditional treatments and physical therapy first. Those are standard lower cost procedures that they are comfortable paying for. Viscosupplementation and PRP treatments are still considered "experimental" and not accepted as standard treatment by most private insurers.
I spent a brief period working in the belly of the medical insurance beast. The system is designed to minimize the benefits paid out. One way to do this is to make you and your provider, who is already overworked, jump through paperwork hoops only for the medical necessity panel to say, "NO!". 95% of people just give up and take what they are given. Of the remainder, the vast majority of appeals fail as your treatment is deemed "not medically necessary" and you end up paying out-of-pocket or accepting standard treatments.
At 65, you are already Medicare eligible but they will very likely force you down the corticosteroid/PT path until a knee replacement is required. They will pay for that procedure because it is standard medicine. If you carry a private supplemental plan, then refer to my comments above.
It's dumb and shortsighted policy but, the insurers and Medicare have us all by the sack and will not let go anytime soon. Ask your provider details about the course of treatment and the costs. Depending on frequency and costs, they might work out a payment plan or you might consider medical tourism to India or Thailand.