Knee Injury

I fell on a cement floor and chipped off a piece of bone in my knee about the size of a quarter. I have had surgery twice and am still in pain. Certain ways I step leaves a stabbing pain in mt knee. I have gone back to the doctor and he said there is nothting he can do for me, that I am an orthopeds nightmare. I now have the damaged area causing bone to chip off of the lower bone as well. My knee kills me to walk up stairs and it grinds like crazy. Is there a doctor anywhere that can do anything to help me. I am 44 years old and have alot of years ahead of me. My activities have been affected greatly. I am not ready to quit the things that I do in general life. Any input you can give me would be greatly appreciated. Thank you.