Adjustment: What causes that pop or crack noise?

After the facial and/or audible reaction to “pop”/”crack” sound of an adjustment, I’m almost always asked the question “What causes that pop/crack noise” and “is it safe?”

Well don’t worry, the sound is not actually your spine or joint “popping” or “cracking”. The actual pop/crack is called a cavitation. The result of the noise is quite similar to the release of gas bubbles when you cork a champagne bottle (I would say that the effect is also very similar)It’s basically the release of gas (nitrogen) that causes the popping sound.

Around many of your joints are capsules, which contain a fluid (synovial fluid) with dissolved gases. During an adjustment the joints are slightly separated, creating a vacuum within the joint capsule. The sound is then created by nitrogen gas rushing in to the partial vacuum created.

But it is important to know that the absence of the noise does not mean that the adjustment was unsuccessful – it only means that there was no noise from the escaping gas.

Why do you adjust the spine? To relieve pain and improve physical function.

Is it safe? When performed by a trained and licenced practitioner… Absolutely.

Are there any side effects? Sometimes a slight soreness and discomfort in the treated area but goes away within a day or two. Serious complications are very very rare.

Any possible side effect should be explained to you by your practitioner and consent should be obtained from you before performing an adjustment on you. If you are still uncomfortable with adjustment – not to worry – there are many other techniques your practitioner can do to relieve your pain and improve physical function.

I hope this helps.

If you have any questions or suggestions for the next post, feel free to ask below or email.


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Osteopath and Medical Acupuncturist. Based in Thurrock and Havering.

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