The Applicance of Science: What causes the creaking and popping of our joints?

We associate certain sounds with getting older, especially ones like cracks, creaks and clicks. Our joints can makes a number of unusual noises as we move about our day, but what exactly causes these funny sounds?
The Applicance of Science: What causes the creaking and popping of our joints?

What causes the creaking and popping of our joints?

We associate certain sounds with getting older, especially ones like cracks, creaks and clicks. Our joints can makes a number of unusual noises as we move about our day, but what exactly causes these funny sounds? Are they anything to worry about and do they really get worse with age?

Naming the sound

Those creaking and cracking noises have an official name, crepitus, which basically covers those audible sound coming from the joints and other specific parts of the body. By definition, these sounds can be painless or accompanied with a varying degree of pain or discomfort. The origin of the word comes from the Latin word, crepare, meaning ‘to rattle’.

Is it a sign of old age?

Our bodies can make these funny noises at any age and stage of life. The joints of children can equally be heard cracking with certain movements. However, There are certain causes of crepitus that are associated with aging of the body.

What causes it?

One of the most common causes of crepitus is gas. The area between the joints is cushioned with a thick, lubricating substance, called synovial fluid. This fluid contains dissolved gases, primarily carbon dioxide (about 80 percent of the dissolved gases) but also nitrogen and oxygen. As we move about and put pressure on our joints, these gases can be forced out of the fluid, creating a small pocket of trapped gas. These bubbles of gas allow the joint a little more movement, before eventually dissolving back into the synovial fluid.

The process that forces the gases from the synovial fluid, creating these pockets, is called tribonucleation. The popping and creaking sounds were originally thought to be the noises made when these bubbles of gas pop. However, more recent studies have shown that the noises we hear are actually created as the pocket of gas forms.

Why can we sometimes crack our joints deliberately?

Many of us can deliberately produce these sounds from our joints, most often our knuckles. We simply push down on the joints to create the pressure needed to produce a gas pocket and create the cracking sound. Although it is not advised to crack your knuckles repeatedly, most studies suggest that it does not cause any significant issues, such as arthritis, later in life.

Although many of us can easily crack our knuckles, we cannot repeatedly do so. The gas in the created bubble must first be re-dissolved back into the fluid before the process of tribonucleation can be repeated.

Snapping joints

The sounds created from our joints are not always the cause of gas pocket formation. Snapping tendons or ligaments around joints, particularly knee joints, can cause some of these sounds. The tendons that pass over the knee joint can sometimes catch slightly on bone or cartilage and then suddenly snap back into their original positions. These types of noises are usually associated with knee or ankle joints, particularly when changing from a seated to a standing position.

As we age our tendons can lose some of their elasticity and this creaking and snapping in the knee joints can become more frequent. Although there is often no discomfort associated with these sounds, the process can become more painful with time.

When there might be a little more to it...

Of course, not every creak or crack should be ignored, especially if it is associated with pain.

Many conditions can cause these noises in our joints, requiring medical attention. It is always best to check with your doctor.

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