Rheumatology is that branch of medicine that concerns itself with the arthritic complaints, mainly rheumatoid and osteo-arthritis. A rheumatologist is a physician who specializes in the treatment of arthritis and other rheumatic diseases that may affect joints, muscles, bones, skin, and other tissues. Most rheumatologists have a background in internal medicine or pediatrics and have received additional training in the field of rheumatology. Rheumatologists are specially trained to identify many types of rheumatic diseases in their earliest stages, including arthritis, many types of autoimmune diseases, musculoskeletal pain, disorders of the musculoskeletal system, and osteoporosis. In addition to four years of medical school and three years of specialized training in internal medicine or pediatrics, a rheumatologist has had an additional two or three years of specialized training in the field of rheumatology. A rheumatologist may also be board certified by the American Board of Internal Medicine.