Cracking knuckles what makes the sound

The authors demonstrated how the pressure omitted by the collapsing bubbles in the knuckle joints produces acoustic waves that can be calculated by their mathematical model. Their research implies that not only can the sound of knuckles cracking be distinguished by their mathematical model, but also that the collapse of bubbles is very likely to result in that equally pleasurable and annoying popping sound.

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Start your Independent Premium subscription today. Recommended Knuckle-cracking mystery solved - but scientists still don't know if. Recommended Knuckle tattoos: Getting creative with eight characters. When small forces are applied to the joint, one factor that limits the motion is the volume of the joint. That volume is set by the amount of synovial fluid contained in the joint. The synovial fluid cannot expand unless the pressure inside the capsule drops to a point at which the dissolved gases can escape the solution; when the gases come out of solution, they increase the volume and hence the mobility of the joint.

The cracking or popping sound is thought to be caused by the gases rapidly coming out of solution, allowing the capsule to stretch a little further. The stretching of the joint is soon thereafter limited by the length of the capsule. If you take an x-ray of the joint after cracking, you can see a gas bubble inside the joint.

This gas increases the joint volume by 15 to 20 percent; it consists mostly about 80 percent of carbon dioxide. The joint cannot be cracked again until the gases have dissolved back into the synovial fluid, which explains why you cannot crack the same knuckle repeatedly. But how can releasing such a small quantity of gas cause so much noise?

There is no good answer for this question. Researchers have estimated the energy levels of the sound by using accelerometers to measure the vibrations caused during joint popping.

The amounts of energy involved are very small, on the order of 0. Studies have also shown that there are two sound peaks during knuckle cracking, but the causes of these peaks are unknown. It is likely that the first sound is related to the gas dissolving out of solution, whereas the second sound is caused by the capsule reaching its length limit.

A common, related question is, Does popping a joint cause any damage? There are actually few scientific data available on this topic.

Does repeated knuckle cracking then lead to arthritis like the superstition says? Klapper, knuckle cracking itself does no harm to your fingers, neck, ankles, or other joints that pop and crack throughout the day—whether from normal day-to-day motions or compulsive habits like pressing our knuckles or twisting your neck until you hear that familiar crack. However, if you experience discomfort while cracking, then there could be a pre-existing condition that is aggravated by twisting and pressing the joint.

Skip to content. But the satisfaction is mostly in your head. Were your parents right about arthritis? It does not lead to arthritis,' says Dr. Click To Tweet. Tags: Expert Advice.