So, what’s the deal with the cracking anyway?
Karen Baker, BSc, DC

There are a lot of preconceived ideas about chiropractic adjustments. And, many people are afraid of the “cracking” sound that often accompanies a classic manual manipulation. Rest assured, the crack you hear is NOT bones breaking, but is a result of gas bubble being released quickly from solution - this sound even has a name: cavitation.

An analogy I often use is that of a soda bottle. You may have noticed that when you open a bottle of pop bubbles seem to form out of nowhere. The carbonation process has infused CO2 into the liquid, and if kept under pressure it will stay there. When the volume of the container holding the liquid increases (or the cap is opened), those CO2 molecules, which would rather be in gas form now have somewhere to go, and come out of solution forming gas bubbles. If you open the bottle slowly, the bubbles form slowly, fizzing to the surface, if opened quickly, they “pop” out of solution all at once.

This is basically the same process as what happens in our joints. Our joints are filled with nutrient rich liquid called synovial fluid. There is nitrogen gas dissolved within this fluid. Unlike a pop bottle, our joints are flexible structures enclosed by a soft capsule that can stretch. As our joints move the volume of the space changes and these molecules escape from, and are reabsorbed into, solution on a regular basis. If the joint moves slowly, these bubbles will form slowly and no noticeable noise will follow, but if stretched quickly enough the gas will pop out of solution making a popping or “cracking” sound.

This being said, you should never agree to a procedure that you are not comfortable with. If you are afraid, there are other ways to get the joints moving that don’t require a crack. So talk to your chiropractor about different treatment methods that might meet your comfort level.