Rheumatology is the specialty of musculoskeletal medicine. There are pediatric and adult rheumatologists who care for a wide variety of both common and rare diseases. With over 100 types of arthritis, rheumatologists must be detectives, gathering clues, using imaging and laboratory studies. Tools of the trade include thoughtful and sophisticated medicines, joint injections, infusion services, laboratory studies, xray and bone density (DXA) machines.