What's actually cracking when you crack your knuckles?

Regarding this column by Cecil: What’s actually cracking when you crack your knuckles?, I know better than to question Cecil on any matter, but I still wonder about this. If this whole phenomenon is cavitation, why do my joints feel differrent after cracking? Why do I feel the need to crack my knuckles from time to time? And why do the bubbles collapse instantaneously after they’re formed.

So many unanswered question on this oh so important subject.

I’ve never posted in this forum before so I hope you don’t think I’m rude to include my comments on this column in your thread.

Cecil states “That’s why you can’t crack the same knuckle twice in rapid succession.” Yet I can do just that with the figer knuckles in my right hand. What happens is when I make a fist I hear popping sounds coming from the three middle fingers. And I can rapidly open and close the fist and it pops every time.

I’ve done it at least 100 in the last few minutes and my fingers are getting tired and while a few sources have dropped out I’m still getting at least one pop from my pointer finger. I’m going to have to stop as my fingers are beginning to hurt.

I do kinda notice that it’s not as loud as when I crack other knuckles. Maybe that has something to do with it.

I used to be able to do a similar thing with my right knee. Lying on my back I’d bend it and then straighten very quickly. I could get off two or three a second and go on for minutes at a time before I got bored. It didn’t always work, though, and I can’t seem to recreate the feat now.

Don’t mistake the finger thing or the knee thing with something like what he mentioned about cracking your back – it could be a ligament or tendon slipping over/off a bone.

My knee used to do that. It’s sort of a cracking sensation, but I don’t think it’s the same thing.

I think you’re right. I’m able to isolate it to just one from my pointer finger. And if I pay close attention it feels like it coming from about an inch south of the base knuckle.

If anyone knows what causes the cracking sound in the knees I would be quite interested in hearing it. It really freaks out my wife when I flex my knees sometimes and get that noise.

I have wondered about this for a long time. I once had a car accident that effected my neck. Sometimes it will get very stiff and sore. If I can crack it, it feels much better. Obviously, sometimes it just ‘feels’ like it needs cracking. My cousin equates this to a ‘chiropractic’ effect and suggests I go to his quackpracter.

I practice some Yoga postions that are very similar to the Physical Therapy exercises I was given way back when. I sometimes even get a crack or two out of my upper back and neck if I’ve been sedentary for too long, like on a road trip.

I doubt this cracking is the same as knuckle cracking, but something similar sometimes happens with my toes, and it hurts like hell until I give 'em a twist.

The joints inbetween your vertebrae are fibrocartilage, a sort of elastic yet fibrous blend of cartilage. This cannot give the same sort of cracking as you get in your knuckles since this is caused by synovial fluid, and there is none in the fibrocartilage joint of the vertebrae.

What fern is probably encountering not actually knuckle cracking, but a slight dislocation of the joint. Opening my fists have never caused my knuckles to “crack”, but I have known people who could “pop” out that joint by the manner you described. This is not the same thing as what Cecil is talking about.

SixSWords, perhaps it is the compression of the fibrocartilage in your neck joints? Do a search in Great Debates with “chripractor” in it, and you’ll probably find some good sites for yourself and to show your friend ;).