Subluxation - What is it?
These subluxations get their name from the word "luxation" which is a complete dislocation of a bone. If you have ever had a luxation you will certainly remember it. A subluxation is something less than a complete dislocation of a bone in a joint. A very slight fixation of 2 bones would classify as a subluxation. When a person gets subluxations adjusted by a chiropractor he/she will tell you that some adjustments involve more change in the affected joints than other adjustments cause change. So, there is a range of degree of how subluxated a joint or 2 or 3 adjacent joints are. The medical profession thinks a subluxation is something closer to a luxation and they generally think the chiropractors are a bit daffy for addressing these slight fixations, and for the chiropractors thinking these are important to health. We will not get into the politics of this different view, but I will say these slight fixations/subluxations accumulate in the body and that these fixations aggravate nerve activity to one degree or another, lesser to greater, depending on the degree of the subluxation approaching a luxation in magnitude. Considering that 25 million people in the United States get adjustments at least once a year, often without insurance coverage, proves that there is at the very least, significant relief attainable. 
There is another term that developed as the chiropractic profession matured and became more sophisticated and that term is the "SUBLUXATION COMPLEX." Not too imaginative but technically a good term. The subluxation complex would concern more than a bone being slightly limited or fixed (a subluxation) relative to its normal range of motion. It would include the ligaments in the area that hold the bones together. It would include the muscles immediately in the area and around the spine. There are numerous small muscles going every which way connecting the spinal vertebrae and rib bones to each other and when I was in school, in anatomy and mechanics class, I could have told you every different kind of muscle and its mechanical function. There are other body functions such as the immune system which responds to stresses, and there is the effect on the lymphatic system and on veins that in part depend on muscle motion to move the lymph and veinous blood along in their return to the heart for recirculation. A fixated/subluxated bone can affect all these in a negative way and always does to some degree even if there is no pain or annoying sensation. Other spinal vertebrae also become subluxated to some degree in relation to the key fixed bone. There you have a look at what is called the subluxation complex.
It is a scientific fact that one of these fixated bone subluxations causes some degree of degeneration to begin within about 2 weeks of the fixation. Why? Well, all these things mentioned in the subluxation complex are negatively affected, leading to a reduction and breakdown of complete function. So, when a chiropractor suggests regular chiropractic visits he is suggesting you protect yourself from this degeneration. How many visits are needed per year to prevent this degeneration is variable person to person but, I doubt you could bring a person into my office or any competent chiropractor's office where at least one subluxation could not be found.
Compensation is another chiropractic term you could hear. More commonly we think of compensation in terms of exchange. You do your job and get the compensation of a pay check or you buy something and give some money for it. You could help a friend who in turn later helps you. In the body if something stops working well, as in a tight muscle or fixed (subluxated) joint, then other parts of the system and in this case the musculo-skeletal system help out by taking on part of the burden. The system starts to shift a little. The more subluxations that accumulate the more shifting occurs.
This should give you a better look at what is going on when a chiropractor adjusts you or uses one of these terms.
Sincerely,
Dr. Mike Spearman