I Have Alot Of Problems With My Knees, 4 Years

I have alot of problems with my knees, 4 years ago I could run down the street, now I cannot go down 4 steps without being in so much pain. I get Cortisone shots but they do not help at all. What is the next course of action to take? I am a 63 year old woman in good condition except the knees.