if im not wrong, i think the same thing happens when you pop your knuckles. But now, i am not sure.

Joints produce that CRACK when bubbles burst in the fluid surrounding the joint.

When you stretch or bend your finger to pop the knuckle, you are causing the bones of the joint to pull apart. As they do, the connective tissue capsule that surrounds the joint is stretched. By stretching this capsule, you increase its volume. And as we know from chemistry class, with an increase in volume comes a decrease in pressure. So as the pressure of the synovial fluid drops, gases dissolved in the fluid become less soluble, forming bubbles through a process called cavitation. When the joint is stretched far enough, the pressure in the capsule drops so low that these bubbles burst, producing the pop that we associate with knuckle cracking. It takes about 25-30 minutes for the gas to redissolve into the joint fluid. During this period of time, your knuckles will not crack. Once the gas is redissolved, cavitation is once again possible, and you can start popping your knuckles again. As for the harms associated with this habit, according to Anatomy and Physiology Instructors’ Cooperative, only one in-depth study regarding the possible detriments of knuckle popping has been published. This study, done by Raymond Brodeur and published in the Journal of Manipulative and Physiological Therapeutics, examined 300 knuckle crackers for evidence of joint damage. The results revealed no apparent connection between joint cracking and arthritis; however, habitual knuckle poppers did show signs of other types of damage, including soft tissue damage to the joint capsule and a decrease in grip strength. This damage is most likely a result of the rapid, repeated stretching of the ligaments surrounding the joint. A professional baseball pitcher experiences similar, although obviously heightened, effects in the various joints of his pitching arm. But assuming you haven’t signed a multimillion dollar contract to constantly pop your knuckles, it hardly seems worth the possible risk to your joints.

Hmmm….maybe it refills much quicker in toes

b_d_41501 you said that when pressure get too low bubbles burst. If they are in the joint capsule and in the synovial liquid where do they burst?

I think that when one can crack joints constantly it`s not because of bubbles (although it can be the in some cases) but it`s because of bad cartilage between bones. It can be chronical like in some diseases (arthitis, badly healed break) or acute like when we sit in front of the computer for several hours and then cracks our neck around.

We’re all entitled to our opinions on how stuff works, but this is something that is proven already. When you press the toe (or apply some sort of pressure to the joint) the joint slightly separates. When this happens the gas makes a pop (or click) sound because it is exiting this separation space. If you Google this you will find the same thing I said earlier. 😀

b_d don`t get emotional. I didn`t mean it in an offensiv way. I just didn`t understood how can bubbles burst. I thought that when bubble burst it means that it has relised it`s gas into some other surrounding gas. Then what happen inside the joint with gas. You mean like fast squizing from one part of joint to another?

And on my courses thay told me that it`s becouse of lack of hijalouronic acid (I hope this is how it should be written).

Not getting emotional 😉 . It may seem that way sometimes but it’s hard to tell the tone of people’s statements over the internet; guess that’s a big disadvantage to debating on here.

I believe a similar effect occurs with nitrogen in the bloodstream when you surface from diving too fast. It doesn’t exactly pop but the decompression does cause extra nitrogen to be present in blood.

@Beetle
At high pressure, the gas disolves in the sinovial fluid. It’s like the disolved oxygen in water, that’s what fish drink. At low pressure, the molecules unite again to form gas.

@Mithril
When you dive nitrogen disolves in the blood. When you surface you need to do it slowly, or else nitrogen bubbles will appear in your blood vesels, causing them to burst. This is called a gaseous embolie. There have been many cases of death due to this phenomenon…

maybe when you pop your toes it’s stretching far enough to release some gas, but not all of it. So you can crack them again and again untill all the gas is released, then you have to wait like the rest of us knuckle crackers

another question… when I dislocated my knee and ankle and the doctors put it back into place they pulled it apart, then pushed it together. It didn’t make the pop untill they pushed them back together. Does this have anything to do with the fluid? Or is it just something with the bones?

Ouch 😮 , how did you do that?

Bones, I think.

The fluid would make the specific sound… But other things will make sounds too… Like you yelling: “Ouuuuuuuuuuuuuuuu!”

yeah i grunted and moaned, but I’m too pridefull to let myself screem! HA. I did it jumping out of an airplane in the Army. Landed wrong on a treestump in the dark.

Ok i don’t really know how the cracking sound works, but the cracking of knuckles/toes that needs a 20 to 30 minutes interval before another crack is somewhat different from the constant cracking of a single toe/finger usually the big toe…

Many people are capable of manipulating and cracking their toe in a way that produces a sound no matter what. Personally, i feel this should be different from the bubbles bursting explanation for common knuckle cracking. As for what exactly causes that, i wouldn’t know… probably just the crossing of the bones at the joints or something like that… No idea…