cavitation crack chiropractic

Holy cavitation Batman!


No, this is not an old Batman episode (POW!) but most often this is what chiropractors are known for. So what exactly is this all holy popping noise we think of when chiropractic is mentioned? Why does it happen? What does it do?  Hopefully this post will help answer some of these questions.

The popping noise actually has a scientific name. Cavitation is the formation and then immediate implosion of cavities (bubbles) in a liquid.

Liquid!?  What does this have to do with my back?

Well, let me tell you.

First, we need to talk about the joints in your back. The vast majority of the joints in your body are categorized as synovial joints. A synovial joint has a small fibrous joint capsule that surrounds where the two bones meet. Inside this capsule is a liquid called synovial fluid. The fluid acts like motor oil for your joints, but much more. Synovial fluid not only lubricates your joints to help them move smoothly, it also supplies nutrition to the joint. So think, “fancy, nutrient motor oil”.

So back to the popping sound we hear when a chiropractor adjusts your back or neck. A cavitation happens in physics when pressure in a liquid is changed rapidly. Small microscopic bubbles will form and then immediately collapse. This creates the popping sound we hear. When a chiropractic adjustment is performed, the two joint surfaces gap apart just enough to create this phenomenon called cavitation within the joint capsule. The bubbles that form within the synovial fluid is carbon dioxide.

Synovial fluid cavitation

The bubbles create the “pop” sound

This popping sound (aka: cavitation) is safe and usually painless. Many people even describe the feeling as nice and relieving. So the title of this blog post is a misnomer. The crack we hear is not a crack at all! I could go on for a few more pages about the cavitation and the effects it produces in the body, but I will save it for another day, another post.

Portland OR Chiropractors at Cascade Chiropractic and Wellness provide customized chiropractic care to the Portland OR, Gresham OR, Clackamas OR, Beaverton OR and Vancouver WA communities.  Visit our main website at

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