Arthritis consists of more than 100 different conditions. These conditions range from relatively mild forms such as tendonitis and bursitis to crippling forms as rheumatoid arthritis. Pain syndromes include fibromyalgia and arthritis-related disorders as lupus erythematosus that involve every part of the body. There are forms of the disease, such as gout that almost nobody connects with arthritis. Osteoarthritis is the most common form of arthritis.