Vertebral subluxation

In chiropractic, a vertebral subluxation means pressure on nerves, abnormal functions creating a lesion in some portion of the body, either in its action or makeup (defined by D.D. Palmer and B.J. Palmer, founders of chiropractic). Chiropractors claim subluxations are not necessarily visible on X-rays.

Straight chiropractors continue to follow Palmer's tradition, claiming that vertebral subluxation has considerable health effects and also adding a visceral component to the definition. Most medical experts and some mixer chiropractors consider these ideas to be pseudoscientific and dispute these claims, as there is no scientific evidence for the existence of chiropractic subluxations or proof they or their treatment have any effects on health.

The use of the word vertebral subluxation should not be confused with the term's precise usage in medicine, which considers only the anatomical relationships.

According to the World Health Organization (WHO), a chiropractic subluxation is a "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". The WHO notes that this is "different from the current medical definition" of a subluxation, which is a "structural displacement" significant enough to be "visible on static imaging studies" such as X-rays. Chiropractic is a field of alternative treatment outside scientific mainstream medicine, whose practitioners (chiropractors) are not medical doctors.

In 1910, D.D. Palmer, the founder of chiropractic, wrote:

Nerves carry impulses outward and sensations inward. The activity of these nerves, or rather their fibers, may become excited or allayed by impingement, the result being a modification of functionating—too much or not enough action—which is dis-ease.

In 1909, D.D. Palmer's son, B.J. Palmer, incorrectly claimed that chiropractic subluxation caused contagious diseases, writing:

Chiropractors have found in every disease that is supposed to be contagious, a cause in the spine. In the spinal column we will find a subluxation that corresponds to every type of disease. If we had one hundred cases of small-pox, I can prove to you where, in one, you will find a subluxation and you will find the same conditions in the other ninety-nine. I adjust one and return his functions to normal... . There is no contagious disease... . There is no infection... . There is a cause internal to man that makes of his body in a certain spot, more or less a breeding ground [for microbes]. It is a place where they can multiply, propagate, and then because they become so many they are classed as a cause.