Think About It Thursday: What Actually Happens When You “Crack” Your Knuckles?


I’m sure we all have that one friend or family member that likes to “crack” his knuckles. But have you ever given thought to what is actually happening in their hands to make that “cracking” sound? Let’s find out!

According to, “In the 1970s, most experts thought it had to do with the collapse of air bubbles in the synovial fluid that lubricates joints.” But apparently there has been new evidence found today that the exact opposite is happening. The sound is is actually caused by the formation of a gas-filled cavity when the bones in joints stretch apart. The cavity or “bubble” of gas forms and then collapses. That is what makes the “popping” sound.

Check out the latest MRI taken of a man who cracks his knuckles!

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