Little white lies
© 2010 Roy Benaroch, MD
What should I do when a parent asks me to lie to their child?
“Doctor, tell him to stop cracking his knuckles. It will give him arthritis.”
This was said to me with a knowing wink– knowing, the parent did, that this myth isn’t true. Cracking knuckles may make mom cringe, but it isn’t going to hurt anyone’s joints.
It you’re curious: When a joint is “cracked” or “popped”, a rapid motion pulls the two surfaces of the joint apart. The space between the joints, just for a quick moment, has a dramatic fall in pressure. During that moment of low pressure, gases that were dissolved in the fluid of the joint form tiny bubbles. The low pressure very rapidly rises back to normal, which crushes the tiny bubbles almost instantly. “Cavitation” is the name the popping noise caused by these collapsing bubbles. After a crack, there is usually a period of time when the joint won’t pop again because there isn’t much gas dissolved in the joint fluid. It takes time for more gas to dissolve, allowing the “pop” to occur again.
Many people can crack their own hand knuckles, or their backs or necks or other joints. People can also learn how to press on the bones of the back or squeeze another’s folded arms to make the same cracking or popping noise. Popping joints like this makes a noise, but otherwise doesn’t affect the joint in any way. It doesn’t “realign” the joint any more than it damages the joint. It’s just a noise.
So: cracking the joint won’t cause any harm, and mom knew it. But she wanted me to reinforce and perpetuate the “little white lie” that her son’s popping habit was going to cause arthritis.
Mom wasn’t happy with my response, which was directed completely towards the boy. I told him that cracking or popping knuckles wouldn’t do him any harm, and certainly wasn’t going to cause arthritis. But I added that cracking knuckles in front of mom was kind of like farting in front of Grandma — not harmful, but not nice, and if you want to make that noise it’s better to do it when mom’s not around.
“But Grandma farts all the time!” was the boy’s response.
You win some, you lose some.