http://en.wikipedia.org/wiki/Osteopathic_medicine_in_the_United_States
Osteopathic medicine is a branch of the medical profession in the United States. Osteopathic physicians, known as DOs, are licensed to practice medicine and surgery in all 50 states and are recognized in forty-seven other countries, including most Canadian provinces.
Frontier physician Andrew Taylor Still founded the profession as a radical rejection of the prevailing system of medical thought of the 19th century. Still's techniques relied heavily on the manipulation of joints and bones to diagnose and treat illness, and he called his practices "osteopathy". By the middle of the 20th century, the profession had moved closer to mainstream medicine, adopting modern public health and biomedical principles. American "osteopaths" became "osteopathic physicians", gradually achieving full practice rights as medical doctors in all 50 states, including serving in the US armed forces as physicians.[1]
In the 21st century, the training of osteopathic physicians in the United States is very similar to that of their MD counterparts.[2]
Osteopathic physicians attend 4 years of medical school followed by at least 3 years of residency. They use all conventional methods of diagnosis and treatment. Though still trained in Osteopathic Manipulative Medicine (OMM),[3] the modern derivative of Still's techniques,[4][5] a minority of osteopathic physicians use it in actual practice.[6]
Osteopathic medicine is considered by some in the United States to be both a profession and a social movement,[7][8] especially for its historically greater emphasis on primary care and holistic health. However, any distinction between the MD and the DO professions has eroded steadily; diminishing numbers of DO graduates enter primary care fields,[9] fewer use OMM, holistic patient care models are increasingly taught at MD schools, and increasing numbers of DO graduates choose to train in non-osteopathic residency programs.[10][11][12]