What the Medical Evidence Says

You may have heard a chiropractic adjustment described in very different ways.

Some explanations say an adjustment “puts a bone back into place,” “realigns the spine,” or removes “interference” or “pressure” from a nerve. Others dismiss it as nothing more than cracking joints as if it were a mere parlor trick.

The medical evidence paints a more nuanced picture.

A chiropractic adjustment, otherwise known as spinal manipulation as referred to in clinical research and medical texts, is a controlled force applied to a spinal joint / joint complex. The force can be delivered by hand, with an instrument or other varieties of equipment. One of the most common types of adjustments is the high-velocity / low amplitude adjustment which may produce the familiar popping or cracking sound. Chiropractors are also trained to adjust / manipulate many other joints of the body, not just the spine ie. shoulders, elbows, wrists, hips, knees, ankles and so on. 

There is an internal and external agreement / disagreement as to what Chiropractors do and what the adjustment does, some cannot even agree on what an adjustment is. So, this is a deep topic without a true consensus. 

So, what is actually happening? Subject to change, as I read the research, evidence, science, whatever you want to call it, this is my take on what the modern Chiropractic Physician does in 2026.  I will make a lot of reference to a “spinal joint” but please understand that you can apply this to pretty much any joint structure in the body.  I would say the human body but there are a lot of practitioners that manipulate animals of all different kinds, more on that later.

An adjustment moves a joint

At the most basic level, an adjustment is a mechanical event where the goal is to restore normal function of the structure being treated.

The practitioner applies a controlled thrust that briefly moves a spinal joint beyond the movement it would / could normally make on its own. This is different from gentle spinal mobilization, which uses slower movements without the same thrust. 

The popping sound sometimes heard during an adjustment is not evidence that a bone has “gone back into place.” It is associated with changes in the pressure within the joint complex during rapid joint movement.

More importantly, there is little evidence that “routine” back pain (whatever that is) is generally caused by individual vertebrae being permanently “out of alignment” and then physically repositioned by an adjustment.

That distinction matters because the strongest evidence for chiropractic manipulation is not that it permanently changes spinal alignment. The evidence is that it can reduce pain and improve function for some people, particularly those with nonspecific (meaning no clear cause) low-back pain.

An Adjustment can break up adhesions within the joint / between joint surfaces

Adhesions also known as scar tissue can be deposited, grow or get laid down between the surfaces of joints. Injury, immobility, certain metabolic / immune diseases / disorders and so on can make an individual susceptible to having adhesions form between the surfaces of the joints. These adhesions limit movement and cause pain. Adjustments, manipulations, mobilizations have been shown in the research to break up / disrupt the intra-articular joint adhesions and restore normal movement and function from a mechanical perspective. Here is a picture taken from an arthroscopic procedure within a joint that demonstrates the adhesions I am referring to.  Think of the adhesions like the formations in a cave – stalactites, stalagmites and columns. Once the growth from each joint surface join, they form a continuous adhesion across the joint surfaces. We do not want this process to occur and if it has already occurred we as providers want to eliminate / break up these formations to restore normal joint function.  Adjustments do just that…

It may change how the nervous system processes pain

One of the more plausible explanations for the effects of spinal manipulation involves the nervous system rather than simply the position of the bones.

Manipulation stimulates sensory receptors in muscles, joints, and surrounding tissues. Those signals can influence how the nervous system processes and regulates pain. Researchers have proposed effects involving spinal reflexes, muscle activity, and pain-processing pathways.

In other words, an adjustment may temporarily change the way the brain and spinal cord interpret and respond to signals coming from the spine and other structures. In doctor-talk, peripheral input from mechanoreceptors modulate / interfere with the transmission of nociceptive afferents to the central nervous system.

That does not mean an adjustment is “resetting” the nervous system in a literal sense. Rather, manipulation appears to be one of several physical inputs that can influence pain, movement and function.

Stay tuned for part 2 – to be continued…

This article is for general educational purposes and does not replace an individualized medical evaluation. Persistent, severe, or unexplained back pain—particularly pain accompanied by significant weakness, numbness, fever, trauma, or bowel or bladder changes—warrants medical assessment.