Scientists Have Discovered What Happens When You Crack Your Knuckles

Ever wondered why you heard that cracking sound every time you, well, crack your knuckles? Sure, the sound is there, but why does it make those popping sounds? Furthermore, is it dangerous or not? Here’s one thing for sure: cracking your knuckles does not cause arthritis. That’s a myth and you should tell your friends about that.

A group of scientists have found out that the cracking sounds originate from the production of a gas-filled cavity located in the synovial fluid that is responsible for decreasing the friction between your joints.

Using MRI

The team of researchers were able to uncover this by using MRI and recording the results of an actual person pulling a finger.

Pull My Finger Study

According to Greg Kawchuck who is the lead author, the results were filmed through the MRI as Jerome Fryer’s fingers were pulled.

The Setup

Fryer’s fingers were pulled by a cable located inside a tube one at a time as the MRI began recording the process. Thus, like a vacuum, a cavity is produced to fill the increasing joint volume instead of the fluid that’s nowhere to be found. And that is how you hear the popping sounds.


Since we are now aware of the origin of the cracking sounds, the team of scientists hopes that this discovery helps in identifying whether the process is ultimately harmful or safe.

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