Degenerative osteoarthritis or just normal “wear and tear” is associated with degeneration of a joint. In this process, the cartilage itself is worn off of the cap of the joint. The underlying bone is then exposed, where there are many nerve endings. That leads to a process people commonly refer to as “bone-on-bone” arthritis. The subchondral bone is very sensitive, and it becomes very painful. Rheumatoid arthritis and avascular necrosis are some other common diseases associated with joint degeneration.