Laurie, I had a partial knee replacement on my left knee in March 2001, that knee has been doing well since then, it's the right knee that is giving me all the trouble now. My ortho doc said the partial replacement I had done should last 10-15 years, then I would need the total replacement. I'm not sure if we are going to try a partial replacement on the right knee, or go for the total replacement if the pain gets any worse.
I tried one of those heating bandages you were talking about, I had a bad reaction,

so I'm not going to be trying them again.
My DW had a total hip replacement when she was 49. She is doing so much better. Before her surgery, she was in so much pain she could hardly walk. I even brought a wheelchair home from work incase she needed it. The only problem she has is with some stiffness from time to time, but at least she doesn't have the severe pain any longer.