We have all heard that if you crack your knuckles, you will end up with arthritis or some other finger ailment. Scientists have conducted a new study to determine what really happens when you crack your knuckles and if there is any long-term damage.
In April, the Inquisitr reported on a study published by the University of Alberta where they used an MRI machine to see inside the hand during a knuckle crack. The study claimed that the popping sound of the knuckles that is heard was due to air bubbles in the synovial fluid. Synovial fluid is the lubricating liquid that surrounds the knuckles and other joints in the body. When a person goes through the motion of cracking their knuckles, an air bubble is formed as a result of negative pressure inside the joint. The entire process is known as cavitation.
Robert D. Boutin, from the University of California, Davis, and his team of scientists wanted to dive deeper into the mystery of what happens when we crack our knuckles. Boutin decided to use an ultrasound in his research study. An ultrasound machine can capture images up to 100 times faster than an MRI machine.
Boutin and his team used 40 test subjects. They were broken down into a group of 30 people who habitually cracked their knuckles and 10 people who did not crack their knuckles. Some of the people in the group of 30 claimed that they had cracked their knuckles up to 20 times per day for 40 years.
The study participants were given the directive to crack their knuckle at the base of each finger, the metacarpophalangeal joint, while inside the ultrasound machine. Boutin and his research team captured 400 knuckle cracks and recorded the sound from the cracks. Boutin did not expect the results of the study.
“What we saw was a bright flash on ultrasound, like a firework exploding in the joint. It was quite an unexpected finding.”
The flash that they saw in the images was the sound of the pop that is heard when we crack our knuckles. Just by looking at the pictures they were able to ascertain which knuckles popped with an almost 94 percent accuracy. Boutin explained to the Metro about his knuckle cracking test results.
“There have been several theories over the years and a fair amount of controversy about what’s happening in the joint when it cracks. We’re confident that the cracking sound and bright flash on ultrasound are related to the dynamic changes in pressure associated with a gas bubble in the joint.”
Questions still remained, though. Does the popping sound come as a result of a bubble breaking or a bubble forming? A study in 1947 stated that the pop comes from a bubble forming in the synovial fluid. That theory was debunked three decades later when scientists said the sound came from the bubble popping. The Alberta study came to the same conclusion, but it still was not completely definitive.
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It was just like trying to figure out if the chicken or the egg came first. Did Boutin’s study find the proof that knuckle crackers around the world were waiting for?
“That’s a surprisingly tough question to answer. I will tell you that we consistently saw the bright ‘flash’ in the joint only after we heard the audible crack. Never the other way around. Perhaps that supports the bubble formation theory, not the bubble popping theory.”
One thing that Boutin was able to determine was that the study was not able to see any difference between the joints of the people who habitually crack their knuckles and the people who don’t. Boutin states that more long-term research needs to be done to prove that no damage is done by people who crack their knuckles. There is also a chance that cracking your knuckles is beneficial as Boutin says, “After a joint cracks, the range of motion for that joint increases significantly.”
Do you crack your knuckles? Do you believe that cracking your knuckles is bad for you?
[Image via YouTube]