I used to work for the Arthritis Foundation, and I also have arthritis myself and have since I was ten. Working there was purely coincidental with having the (well, a, since there are more than 100 types of arthritis) disease, but overall it was a great experience. I've since left the AF and now work for a medical device company, and from time to time we get questions from TV shows -- mostly ER and once from Nip/Tuck.
Back at the AF, we would occasionally get inquiries from authors about the aspects of having a particular disease (treating lupus is different than treating rheumatoid arthritis and so on), though we did have one person who was doing a survey of arthritis mentioned in fiction -- and from what they found, most of the time it was an older (60+) person with osteoarthritis and anyone younger or with an autoimmune type was a rare find. Then again, I have rheumatoid arthritis and don't consider myself disabled (neither would my rheumatologist), though it can be disabling and there are many who have been disabled by it, so it also depends on the way you define disability.