Which arthritis is a particularly prevalent disease and comes in two forms: osteo- and rheumatoid arthritis. Osteoarthritis develops over a long period of time, and generally the cartilage roughens and becomes thin, while the bone becomes thinner. Extra synovial fluid, that lubricates the joint, can be formed and that causes swelling. The bone tried to repair itself, but degeneration continues and the tendons become affected. Eventually inflammation can occur leading to severe swelling and pain. There are several causes, the most common being injury or repetitive hard use of the joints.