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Many people are familiar with a snap, crackle and a pop in joints after a run, jog and maybe after sitting for a long time.

Others crack when they squat or go through the full arc of motion even though they don’t experience pain.

For some people popping their fingers or cracking their knuckles can be a habit of releasing stress or just something that they do for the fun of it.

But have you ever wondered why joints crack and pop painlessly?

According to Laticia Pienaar, principal communications officer at Tygerberg Hospital popping joints can occur spontaneously when a joint is moved through its normal range of movement, or it can be induced by pulling on a joint, usually habitually pulling on the finger joints.

“When a joint is pulled, a negative pressure occurs in the joint that will lead to the formation of bubbles that were normally dissolved in the natural fluid of the joint.

“As the fluid moves to the bigger joint space created by the pulling, the larger bubbles tend to burst and create the cracking or a popping sound.

“In larger joints such as the knee, these bubbles may also form spontaneously leading to painless popping when moving the joint,” she said.

She said most people who habitually cracked joints felt subjective relief in the joint.

“This may be due to the fact that the joint space is temporarily bigger with laxer ligaments improving the range of movement in the joint.”

This was however, temporary, and would last about 15 minutes at which time the joint space moved back to normal, and the bubbles were dissolved again, hence it takes about 15 minutes for a joint to crack again.

Excessive pulling on a joint, beyond the limitations of the supportive ligaments or tendons may also lead to ligament and tendon injury.

“Common urban legend suggests that cracking may lead to osteoarthritis, degenerative arthritis of the joints.

“Although there are individual reports of joint damage or injury, there is no convincing scientific evidence to support the development of arthritis due to cracking of joints.”

When asked if a cracking joint could indicate a health issue, Pienaar said should the spontaneous cracking of joints be associated with pain and discomfort, it may indicate underlying arthritis or a soft tissue structure problem, tendinitis or ligament injury as the cause.

In this case, the sound is not due to the popping of bubbles in the fluid, but rather due to the movement of damaged cartilage surfaces.

ABC Health and Well-being reported that noise plus pain is much more an indication of a problem needing medical input than a noisy joint with a pop here and there. But when in doubt about the risk, they suggest that you ask your doctor or physiotherapist to check it out so you can treat it.

A loud, low-pitched “clunks” can be a warning sign of serious joint problems, especially in children.

“There are some clunks that can be quite important.”

Partially dislocated hips that are not diagnosed for instance can wear cartilage out at a very young age, causing life-long disability.

For adults it’s different, hearing just a bit of cracking is more likely to be just a bit of “getting old” .