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11/24/2024 04:39:29 am

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Why Joints Crack: Scientists Reveal the Reason for that Weird Popping Sound

Many of us have acquired the habit of cracking knuckles while others detest it, but scientists have been wondering what actually causes it and what happens to our hands when we crack our knuckles.

Researchers have finally revealed the answer as to what occurs inside the knuckles and how the familiar popping sound is produced using magnetic resonance imaging or MRI experiments. Scientists have dubbed this experiment the "pull my finger study".

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The cracking sound is caused by rapid gas formation inside a cavity found within a slippery substance called the synovial fluid. This fluid is responsible for the lubrication between the spaces in the finger bones. This knuckle cracking process occurs in less than 310 milliseconds, according to scientists.

Researchers also captured a white flash before the popping sound occurs caused by water rushing together.

The sound is pleasant to me but it could just be my inner nerd who's talking, said Greg Kawchuk from the University of Alberta in Canada and lead author of the study.

The first scientific study regarding popping joints was conducted in 1947 and confirmed this finding the sound is being produced by a formation inside a gas cavity within the joint. A 1971 study, however, challenged this theory saying the collapse of a bubble inside the joint is the trigger point for the pop.

This new study pulled he fingers of one man and captured this knuckle cracking motion via MRI video. MRIs usually provide detailed images of internal body structures and organs.

Study co-author and chiropractor Jerome Fryer even used his fingers and knuckles for this study. He inserted these joints in a tube linked to a cable that pulled his fingers until his joint cracked.

According to Richard Thompson of the University of Alberta, rapid imaging using MRI was perfect for these studies to reveal a clear visualization of the hand bones and fluids surrounding them, especially the formation of that air cavity.

Kawchuck adds that prior studies suggest the knuckle cracking habit does not induce any harm.

This study was published in the journal, PLOS ONE.

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