Mskari85, for a long time RA and OA have been thought of as separate conditions - the immune system is involved in RA but not in OA.

However, this is a bit simplistic - immune system proteins, notably some of the complement proteins, seem to be involved in the inflammatory response in OA - see Identification of a central role for complement in osteoarthritis.

I don't know if this has led to improved therapy but it is something that you could discuss with your rheumatologist.