Chiropractic was founded in 1895 by D. D. Palmer, and it is now practiced in over 100 countries.  Chiropractic comes from the Greek words chiros and praktikos meaning "done by hand" and is a well recognized health care profession (practitioners are called Chiropractors) used to diagnose and treat mechanical disorders of the spine and musculoskeletal system.   Chiropractic treatments also affect the nervous system and are based on the theory that spinal joint dysfunction can interfere with the nervous system and result in various disease states and can diminish health and wellness of individuals. Some practitioners of Chiropractic use the term vertebral subluxation to describe what they treat, while others have dropped this concept and primarily focus on the musculoskeletal components of spinal injury and spine rehabilitation.  While well accepted by many patients and some insurance companies today, the Chiropractic approach has historically been outside the mainstream of conventional medicine in the United States.  Chiropractic has grown in acceptance and influence.  The World Health Organization states that when "employed skillfully and appropriately, chiropractic care is safe and effective for the prevention and management of a number of health problems."