Not sure how old you are but you possibly have osteoarthritis in your knees and that can be treated with hyaluronic acid (knee gel) injections that are steroid sparing and actually do a great job of taking the pain away. The gel is a synthetic form of what you had protecting your knees in your youth. Better relief and better for your overall health than a steroid. I have been getting them for several years and the injections are like magic for me.
BTW, I am on 10mg prednisone and trying hard to get completely off - steroids cause naughty problems, especially long term. I would do anything to get off.