What’s the Sound Heard During a Chiropractic Adjustment?

The sound heard during a chiropractic adjustment is often referred to as a “crack” or “pop.” It is the result of a sudden and rapid separation of joint surfaces, which can create a change in pressure within the joint and cause dissolved gases, such as nitrogen and carbon dioxide, to form bubbles. The sound is similar to the sound that occurs when you crack your knuckles.

Theory #1

While the exact cause of the popping sound is not fully understood, recent research suggests that it may be due to a phenomenon called tribonucleation. According to this theory, the rapid separation of joint surfaces during a chiropractic adjustment causes a drop in pressure, which allows dissolved gases to form bubbles. When the bubbles collapse, they produce a popping sound.

Another Theory

Another theory suggests that the sound heard during a chiropractic adjustment may be due to the movement of synovial fluid within the joint. Synovial fluid is a lubricant that helps reduce friction between joint surfaces. When a joint is manipulated, the movement can cause a change in the pressure of the synovial fluid, which may produce the popping sound.


While the popping sound itself is not a reliable indicator of the effectiveness of a chiropractic adjustment, it can be reassuring to patients who may be experiencing pain or discomfort. It’s important to note that not all chiropractic adjustments result in an audible pop or crack, and that the sound is not necessary for the adjustment to be effective.


This all sounds like something straight out of Bill Nye’s science experiments, doesn’t it? While the exact mechanism is not fully understood, we see patients benefit every day from chiropractic treatment. Something else worth noting – sometimes adjustments to joint structures may not be necessary. A lot of treatment options are available in our offices. After a thorough evaluation, your chiropractor will discuss with you what the best treatment option(s) will be. All treatments are specifically tailored to you!



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  2. Noda T, Nakamura T, Fujita K, et al. Tribonucleation-induced cavitation generates effective sonoluminescence. Sci Rep. 2019;9(1):20144. doi: 10.1038/s41598-019-56550-6. PMID: 31882577; PMCID: PMC6931043.
  3. Shashua A, Fleury A, Osherov V, Barak MM, Gefen A. Effect of cavitation on the internal mechanical response of spinal tissues. Med Eng Phys. 2019;70:54-61. doi: 10.1016/j.medengphy.2019.05.015. PMID: 31202023.