What’s the POP?

Chiropractic is crack a’ lackin’ good times—literally. Most patients hear a noise like a pop or crack when they receive manual chiropractic treatments. I always make a point to tell any new patient I’m treating that the “pop” they might hear with a chiropractic adjustment is not their bones breaking—that I’m not Jackie Chan or Rambo or The Rock. I HAVE been called Dr. Crackenstein, which cracks me up (yes, yes I did just do that), but the question then inevitably comes up—what IS that noise if not something breaking or being hurt? Short answer: it’s gas.

Let’s take a step back and look at the basics. The joints in the spine are called synovial joints, which are the most mobile and prevalent joints in the human body. When these joints move, they require lubrication to allow for ease of movement, as well as nutrition and protection (think the oil in your car allowing the mechanics of the engine to move freely and without disruption). The fluid in the spinal joints is called synovial fluid, and it’s constantly moving in the joint space in tandem with the motion of the joint.

There are actually a few theories as to what the pop is, but the most prevalent and widely accepted of them says that the contents of the joint space undergo a change in pressure when the joint is moved into its paraphysiological space (the end of its normal range of motion), allowing the gas inherent in the synovial fluid (Carbon dioxide, Oxygen, and Nitrogen) to “release,” causing a “cavitation,” AKA popping noise. That’s it—just some gasses escaping the joint space. Because chiropractic adjustments or manipulations take the joint into their end ranges of motion, you consequently hear those pops.

So what if you DON’T hear a noise when you go to the chiropractor? Does this mean nothing happened? Something we’re told when going through chiropractic school is “don’t be a crack addict.” While this is good advice in general, it’s specifically relating to students the importance of recognizing a joint may be mobilized and proper biomechanics restored without that audible release of gas. Many things can affect the ability of a joint to produce a popping noise with chiropractic treatments, such as temperature, barometric pressure, inflammation, or contracture of the surrounding musculature. So just because you didn’t hear any popcorn-like noises does not mean your joints weren’t properly mobilized by the chiropractor.

Bottom line, those pops that you tend to hear when you’re being adjusted by your chiropractor are harmless releases of normal gasses. Might as well enjoy them, since they’re more socially acceptable than other releases of gasses!

Protapapas, Marina G., and Cymet, Tyler C. “Joint cracking and popping: Understanding noises that accompany articular release.” The Journal of the American Osteopathic Association Vol 102. No 5 (2002): 283-7. Print.

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