Vertebral Subluxation is a chiropractic term that is used to describe myriad signs and symptoms (syndrome) thought to occur as a result of a misaligned or dysfunctional spinal segment. Chiropractors believe that a subluxation complex is a functional biomechanical spinal lesion that can alter neurological function, which in turn, is believed to cause neuromusculoskeletal and visceral disorders. Officially, the WHO definition of the chiropractic vertebral subluxation is:
A lesion or dysfunction in a joint or motion segment in which alignment, movement integrity and/or physiological function are altered, although contact between joint surfaces remains intact. It is essentially a functional entity, which may influence biomechanical and neural integrity.
The purported displacement is not necessarily visible on X-rays. This is in contrast to the medical definition of spinal subluxation which, according to the WHO, is a "significant structural displacement", and therefore visible on X-rays.
Chiropractic's early philosophy was rooted in vitalism, spiritual inspiration and rationalism. A philosophy based on deduction from irrefutable doctrine helped distinguish chiropractic from medicine, provided it with legal and political defenses against claims of practicing medicine without a license, and allowed chiropractors to establish themselves as an autonomous profession. This "straight" philosophy, taught to generations of chiropractors, rejects the inferential reasoning of the scientific method, and relies on deductions from vitalistic first principles rather than on the materialism of science. However, most practitioners currently accept the importance of scientific research into chiropractic, and most practitioners are "mixers" who attempt to combine the materialistic reductionism of science with the metaphysics of their predecessors and with the holistic paradigm of wellness; a 2008 commentary proposed that chiropractic actively divorce itself from the straight philosophy as part of a campaign to eliminate untestable dogma and engage in critical thinking and evidence-based research.
Although a wide diversity of ideas currently exists among chiropractors, they share the belief that the spine and health are related in a fundamental way, and that this relationship is mediated through the nervous system. Chiropractors study the biomechanics, structure and function of the spine, along with what they say are its effects on the musculoskeletal and nervous systems and its role in health and disease.
