Some love to do it, others dislike the sound greatly. But what really happens in the joint when “cracking knuckles”? Researchers have found the answer.
It is an international research team led by University of Alberta who have used MRI video to see what happens inside finger jointed when cracking knuckles – that drag your finger so that a sound occurs.
– We call it ‘pull my finger study “and what we did was actually pulling someone’s fingers and filming what happens with MR. When one does, one can see very clearly what is happening inside the joint, said lead author of the study, Professor Greg Kawchuk at the University of Alberta, in a press release.
According to the study published in the journal PLoS ONE Wednesday formed a kind of vacuum and a gas bubble which gives off the familiar sound when it burst.
Watch video at the top of the article.
Read also: Vile, but harmless crack sounds
Several theories
Although it might not be the world’s most important issues, it has been debated for years. Already in 1947 meant British scientists that the formation of a gas bubble could be the explanation for the sound. In the 1970s, other researchers believed that sound rather was due to a gas bubble in the joint burst, according to the press release.
This gas bubble that burst, has been a leading theory in a long time, but scientists would any process with their own eyes and decided therefore to examine the inside of the wrist as finger was dragged in, using MRI technology.
It was chiropractor Jerome Fryer who had the idea for the project. Because he is also very good to crack your knuckles, it was his fingers that were filmed in cracking process.
Fryers fingers were one after another pushed into a tube, which was attached to a cable, which was slowly pulled until knuckle gave up the characteristic sound.
It happened every time knuckle giving the sound, in less than 310 milliseconds, was caught on video.
Cavities in liquid
A paragraph cave is filled with synovial fluid, which acts as a lubricant for the joint.
In each case, cracking sound and the joint was pulled in, associated with a quick formation of a gas-filled cavity inside the synovial fluid.
– It is a bit like creating a vacuum. As joint surfaces suddenly pulled apart, becoming more fluid available to fill the increased volume, so a cavity occurs and that is what linked to sound, says Professor Greg Kawchuk press release.
In the process researchers discovered also a white flashes that occur just before the sound comes. This is according to Kawchuk not previously been observed. He now wants to spend even more advanced MRI technology to understand what happens after that the sound occurs and what it may mean for joint health.
– Buckling does not gout
The researchers behind the fresh study has not taken on and if so, how it is to crack the knuckles associated with joint health.
It was long a widespread perception that the cracking knuckles of the fingers could cause gout. But this has long since been disproved, among others by the doctor Donald Unger who used themselves as guinea person.
For 50 years he snapped knuckles of one hand, while on the other joints were left in peace.
Then he examined the joints thoroughly, and it was ascertained that there was no difference between them. They were equally healthy.
For this research got Donald Unger Ig Nobel Prize, a parody of the real Nobel Prize given for investigations “first make people laugh and then make them think,” according Videnskab.dk.
As we now know why the crunchy sound arises, why not test how it sounds when 1000 joints cracked in tie:
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