The primary doctor to treat arthritis may be an internist, a doctor who specializes in the diagnosis and medical treatment of adults, or a rheumatologist, a doctor who specializes in arthritis and other diseases of the bones, joints, and muscles. As treatment progresses, other professionals often help. These may include the following: Orthopaedists: Surgeons who specialize in the treatment of, and surgery for, bone and joint diseases. Physical therapists: Health professionals who work with patients to improve joint function.