Ever since I can remember, I have been told that popping your knuckles will lead to arthritis when you get older. Is this really true? Is there evidence for this? I pop my knuckles at least 10 times a day and was just wondering if anybody knew if this really leadt to arthritis.
My semi-WAG is no, of course not. There are little air pockets in your joints, and all you are doing is popping those bubbles. I can’t imagine how that would lead to arthritis…unless, those air pockets help cushion the joints and by popping them you cause the joints to rub together more, in which case, yeah, yer headed for crippling arthritis someday.
Duzzat help? 
Cecil did a column about this.
I had arthritis way before I started this annoying habit.
When I was studying Occupational Therapy (and Hand Anatomy) our instructor told us that it can be a factor in arthritis, because you can get over-zealous and stretch the ligaments in your finger joints. And when you consider that some people do this a few times a day, every day, I think its feasible.
He didn’t say that it CAUSES it, but it can BE A FACTOR.
But IANAD.
YMMV.
Is the same true for necks?
Nope, your joints are full of fluid. Popping your knuckles causes “cavitation”, or in other words, you reduce the pressure so much that the fluid boils. It boils violently with a single bubble which expands at enormous speed.
Hmmm. I never thought of this before, but cavitation boiling generates shock waves which commonly destroy turbines and motorboat props. Maybe the “pop” is so intense that it can damage the neargy cartilage in your joints?
You can make a visible analog of knuckle-popping if you have an old plastic syringe. Fill it competely with water, then get rid of any bubbles. If you now block the opening and pull on the plunger, a large bubble will appear from nowhere. You made a vacuum, and the water boiled at room temp.
There is a type of bottom-dwelling tropical shrimp which has harnessed knuckle-popping into a weapon. The shock wave stuns prey. It’s like killing fish with dynamite, but on a much smaller scale.
No kidding? I have something similar. Sometime during my late adolescence I apparently developed the mutant ability to pop my middle knuckles on both hands merely by closing them into fists. I can pop them over and over in succession by clenching. Granted, it can’t affect fish, but I can really do great nerve damage to my friend Dave, who is extremely squemish about knuckle cracking (he likens it to bones grinding together).
bbeaty: Nope, your joints are full of fluid. Popping your knuckles causes "cavitation"
He’s right.
It’s fluid - Not Air.
And in time - popping those little sacs (which are there to provide joint lubrication) will start to dry out - Which is what can lead to arthritic pain.
i don’t think **Stoid ** said any different; simply left out some details. anyway,
**And in time … those little sacs (which are there to provide joint lubrication) will start to dry out **
i don’t believe that. i mean, not to say i won’t believe it, but that i don’t. how will popping bubbles of gas inside a closed chamber cause the gas to disperse outwards?
jb
<nitpick>
Air is a fluid. You meant liquid…schools these days…
</nitpick>
Still, I always though it was a gas. This whole fighting ignorance thing just might be working.
Here’s articles about shrimp-y shock waves:
http://news.bbc.co.uk/hi/english/sci/tech/newsid_935000/935855.stm
http://physicsweb.org/article/news/04/9/13
I also remember seeing something about the Mantis Shrimp, but now I can’t find it. Mantis Shrimps were always thought to bash things with their claws, but someone found that they actually generate underwater shock waves. Makes sense, since if you move fast enough while underwater, just the water alone will damage whatever it strikes.