Where is that sound coming from?

chiropractic adjustment - 1This was my first question when I visited a chiropractor in 1995. I was just a young student fresh out of UBC and wondered what I was going to do with my Bachelor of Science Degree in Biopsychology.Medicine didn’t appeal to me much because I wasn’t a big fan of the on-call hours and most importantly, I didn’t want to be influenced by big pharma. I also wanted to offer my fellow man (or women) the most natural and effective approach to health care possible. I liked the idea that I didn’t have to prescribe medication and that fundamentally if the physical body is working well, it has the ability to heal. And as most people affiliate chiropractic to the release of spinal joints, here I am 18 years later, ready to answer that first question I had as a patient myself: where is that sound coming from with a spinal manipulation?


Travelling through chiropractic college, I had a keen interest in understanding what the sound of a manipulation was all about. It is a curious sound. A pop, a snap, a crack. We were trained to manipulate joints to target the “crack” as an end goal. The instructors encouraged us if we performed the adjustment correctly, and I soon learned that they wanted us to cause a cracking noise. Still, I needed to find out what this crack was all about.


To date, researchers think the sound comes from a collapsing bubble formation under a suddenly low pressure change in the joint. In science, we have seen a bubble form after an adjustment and the gas is supposedly, Nitrogen. This bubble forms through physical chemistry as a phase changeoccurs from a diffused liquid to a gas. I personally don’t think this bubble is responsible for the noise. Undoubtdly, there is no dispute that a gas bubble does form but is it the thing repsonsible for the “popping ” sound? The research is not yet complete and we should be foolish not to continue to investigate why some joints respond well to manipulation, and why some perhaps may not. Some joints will not crack no matter how good the chiropractor is. Some joints are instrincally stiff or degenerated, or even too flexible and have physical properties that do not allow them to crack. Some joints don’t even need to crack for treatment. I believe there are clinical clues as to which joints should be manipulated and why some respond better to other forms of manual treatment.


If you want a review on this sound, you can read it here. Two important key points from these authors, one author being from physical medicine and rehabilitation at Harvard University’s Harvard Medical School, is that:

  1. The noises that accompany joint motion have not been studied extensively
  2. The noises of normal and abnormal joints are built into the nature of the structures. To ignore these noises would be foolish, as they might be used to help determine the effectiveness of treatment.

Yes, if you can believe it or not the specific sound emitted from a synovial joint crack has still not been defined. Three years ago I approached UBC with research methods to test further and define the anatomical structure repsonsible for the noise in joints. The idea moved very near to being started but the limited factor was funding. I will get to this one day, I hope.

In the meantime, I have finally developed a spine model that goes “CRACK”. I have always dreamed of being able to show my patients where the sound is coming from. This is in line with my belief that it is the articular cartilage making the noise. Other fellow researchers think this as well. We just have to prove it. I will one day, unless someone beats me to it. And that is OK too.
If you want to see this new model click here, or click on the picture below. It may help you understand why I manipulate some spines in practice, and decompress the disc in others.


chiropractic adjustment - 2