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A weekly show where we endeavor to answer one of your big questions. This week, seanjedi97 asks, "Does popping your knuckles really cause arthritis?"


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Hi I'm Craig and this is Mental Floss video. Today I'm gonna answer seanjedi97's big question, "DOES POPPING YOUR KNUCKLES REALLY CAUSE ARTHRITIS?" Well your commenting in all caps causes tinnitus.

So between 25 and 54% of people do this and men are more likely to crack or pop their knuckles than women, but does it cause or increase the risk of arthritis? Let's get started.

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First I want to explain what's actually happening when you crack your knuckles. The joints in your fingers are diarthrodial joints which means there are two bones with cartilage in between them. Around that cartilage is a joint capsule, which also contains synovial fluid and when you put pressure on your fingers like when you crack a knuckle, the synovial fluid tries to expand, in order to make that happen some gasses get released in the form of little gas bubbles. So it's like a little knuckle fart.

So that doesn't sound like such a big deal but some still say there's a connection between knuckle-cracking and arthritis. There are a few studies about this. One particularly interesting one was conducted over the course of about 50 years by Dr. Donald Unger from California. Every day he cracked the knuckles on his left hand at least twice and  he hardly ever cracked the knuckles on his right hand. According to his research paper, "the knuckles on the left were cracked at least 36,500 times, while those on the right cracked rarely and spontaneously." He didn't develop arthritis or notice a difference between the two hands over 50 years, but using one guy as an example doesn't really prove much.

One of the most commonly cited studies on this was conducted in Detroit during the 90s. There were more than 300 participants and researchers observed that people who cracked their knuckles were more likely to have swelling in their hands in addition to a weaker grip, but they weren't more likely to have arthritis. And a 2010 study published in the Journal of the American Board of Family Medicine had similar results. Of the 2013 participants between the ages of 50 and 89, 18% of people who cracked their knuckles had arthritis and 21.5% of people who didn't crack their knuckles had arthritis, so no connection was found. So I'm gonna keep cracking my knuckles. Basically researchers have yet to find a link between knuckle cracking and arthritis so crack away, but don't do crack.

Thanks for watching Mental Floss video which was made with the help of all of these knuckleheads. If you have a big question of your own that you'd like answered, leave it below in the comments and next week we'll take a crack at it.