What Happens When You Crack Your Knuckles

Knuckle-cracking was not tied to short-term health effects

Despite the wives’ tales that tie cracking your knuckles to problems like arthritis, many habitual knuckle-crackers just can’t help themselves. But do they really have anything to fear?

Probably not, a new study suggests. The authors of this study recently figured out what makes that wonderful popping sound when you crack your knuckles — and in the process, they found that knuckle-crackers didn’t see any health effects tied to the habit.

“We found that there was no immediate disability in the knuckle crackers in our study, although further research will need to be done to assess any long-term hazard — or benefit — of knuckle cracking,” said Robert D. Boutin, MD, a professor of radiology at University of California Davis Health System, in a press release.

So tell the no-knuckle-cracking naysayers they’ll have to wait until more research on the subject is published. The current study looked at 40 healthy adults. Thirty of these patients habitually cracked their knuckles.

Dr. Boutin and colleagues examined the patients using ultrasound imaging to capture what exactly is going on in your hand when you crack your knuckles.

“What we saw was a bright flash on ultrasound, like a firework exploding in the joint,” Dr. Boutin said. “It was quite an unexpected finding.”

That sounds like it could be damaging, but Dr. Boutin and team found evidence to the contrary. Compared to patients who didn’t crack their knuckles, knuckle-cracking patients had similar grip strength. Also, immediately after cracking their knuckles, there was no evidence of swelling, pain or similar problems.

As for what’s behind the “pop” sound your knuckles make, Dr. Boutin and team think they found the answer.

“There have been several theories over the years and a fair amount of controversy about what’s happening in the joint when it cracks,” Dr. Boutin said. “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.”

This study was presented at the annual meeting of the Radiological Society of North America. Research presented at conferences may not have been peer-reviewed.

Information on funding sources and conflicts of interest was not available at the time of publication.


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