Click, Pop, Crack….What ever you call it, what causes it?

The correct name for a sound made during a chiropractic adjustment is a ‘cavitation’. It was once thought that this sound was produced due to a bubble being popped inside the joint, but recently this phenomenon has been recorded via MRI and analysed in depth to show the true cause of a cavitation.

Anatomy - The most common joint in the body is called a synovial joint. A synovial joint has a capsule surrounding it which contains a fluid called synovial fluid, this contains a mixture of fluid and gases which together help protect the joint.

Science lesson - Boyle’s law states that when you increase volume of a fluid that's contained (i.e. move the 2 joints apart) the pressure decreases proportionally. This pressure decrease within in the joint causes some of the liquid to turn into gas, (mainly carbon dioxide) very rapidly which causes the cavitation that you hear.

To see a video of this in action click the link below!

https://www.youtube.com/watch?v=aJLU-4M-hdE