Um, I don't think PN can affect the knees and elbows, at least not in terms of the joint. So, if the joint is painful, then look for another cause. Arthritis etc is very common, so there may be a co-existing condition.

It people are experiencing pain on the skin covering joints then that could be PN I am thinking. There are also tendons etc around joints which can cause problems and be painful, but again this is not PN, it's more likely to be tendonitis.

I get arthritis from my lupus. I do have problems moving some joints which is caused by my PN because I have sensory motor PN and the motor part of my PN means that i am loosing the ability to move parts of me (eg. I can't lift my left leg). But joint pain itself is not part of PN, as far as I know.

cheers
raglet