I'm not sure of Beanie's age. Luxating patella can be corrected by surgery. It is usually (not always) a genetic problem. I can give you a link with several articles of info:
http://www.bichonfriseusa.com/ref/luxpat/home.htm
Regarding Rimadyl. The Senior Dog Project found that the side effects heavily outweighed any benefits, and determined that Rimadyl is not safe for older dogs. Can you get a substitute? Tramadol and Matacam are the two suggested substitutes.
I'll say some prayers for Beanie that you and the white coats can figure out a way for his to be more comfortable.