If you crack your knuckles, you’re not alone.

It’s an extremely common habit; in fact, somewhere from 25 to 45 percent of people crack their knuckles voluntarily, according to one study. 

To some, it’s fairly annoying. We’re not here to debate whether the sound of cracking knuckles is obnoxious—it is, of course—but we did wonder whether or not it’s actually dangerous. Your mother might have told you that cracking your knuckles leads to arthritis; is it really that harmful?

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First, it’s helpful to understand what’s really happening when you’re cracking your knuckles.

Oddly enough, that’s been a source of debate among scientists until recently. For decades, scientists believed that separating the knuckle created a pocket of air, which “popped,” issuing the telltale sound.

This turned out to be untrue. By using an MRI machine, researchers were able to monitor the process and show that separating the bones creates a temporary space with a little more room in it, and synovial fluid rushes into that space. That creates the popping sound, and yes, we’re sorry for the mental image.

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This isn’t thought to be bad for joints since it doesn’t put any unnatural stress on them. However, in the world of science, research rules, so several studies have attempted to address the idea that cracking knuckles can lead to joint pain.

The most famous study was performed by Donald L. Unger.

For 60 years, Unger cracked the knuckles of his left hand, while purposely avoiding the knuckles on his right hand. He didn’t develop any joint pain, arthritis, or other issues in his left hand and he, therefore, declared that knuckle cracking was harmless.

This was an impressive achievement, but not quite scientific; Unger didn’t test his hypothesis on nearly enough subjects. However, it did win him an Ignoble Prize, an award given out to the most ridiculous scientific studies of each year. 

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Unger was a good sport and accepted his award himself. 

“Mother, I know you can hear me,” he said in his acceptance speech. “Mother, you were wrong! And now that I have your attention, can I stop eating my broccoli, please?

A more credible study from the Radiological Society of North America had similar results.

The study looked at the joints of 40 volunteers, before and after they’d cracked their knuckles. Researchers measured range of motion, grip strength, and a number of other factors. 

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Their findings? There was, predictably, no short-term damage to the “cracked” knuckles. In fact, the people who cracked their knuckles actually had more range of motion than their un-cracked counterparts.

Other studies have had similar findings. Cracking your knuckles doesn’t really help you, per se, but it doesn’t hurt, either. It doesn’t seem to cause arthritis. It doesn’t seem to cause joint pain.

It can, however, annoy your coworkers; something to keep in mind when the urge to crack hits you. 

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