Ever wondered what's that ‘pop’ sound we hear while cracking our knuckles, feeling relief and satisfaction? This sound is heard due to ligament expansion. And in drastic conditions, even our bones grind against each other!

Similar popping sounds can be heard in other parts of the body like our wrists, toes, hips, and neck. These parts, in particular, are the synovial joints that join bones or cartilage with a fibrous joint capsule.

MECHANISM OF A KNUCKLE POP

These synovial joints are filled with a fluid called synovial fluid. This fluid contains long and lubricating molecules like lubricin and hyaluronic acid. They function as a cushion between the two bones and help the bones pass each other efficiently. Another major function performed by this fluid is that the phagocytic cells present in it clean up the flotsam and jetsam that may have ended up between the joints.

The synovial fluid has numerous gas molecules present in it and when we stretch our finger, our bone moves further than it normally used to, creating a ‘low-pressure zone’. This pulls out all the dissolved gas molecules from the fluid leading to the formation of bubbles. Due to the pressure exerted on the bubbles, they burst and scatter throughout the fluid creating the ‘pop’ sound. It takes around 15 minutes for the bubbles to regain their original size which is the reason why we can't pop the same joint again and again.

DOES KNUCKLE POPPING CAUSE ARTHRITIS?

We might have heard people telling us not to crack a knuckle since it might weaken our joints. Well, this is not true. Popping enlarges the joint giving a weak feeling, which is the reason why people think it causes arthritis, but this is completely temporary!

DR. DONALD UNGER’S STUDY

Donald Unger, as a child, while popping his joints, had his mother telling him not to do so since it would lead to arthritis. To disprove his mother's theory, he popped the fingers of his left hand and left the right hand unpopped for 60 years! After popping his joints 36,500 times, both his hands turned out to be arthritis-free! For his super fascinating study, he even received the Ig Nobel Prize!

Knuckle popping might not be dangerous, but it certainly might annoy the people around you!

IG NOBEL PRIZE

“Achievements that make people laugh and then make them think”

The Ig Nobel prize recognizes interesting science studies since 1991 that society would otherwise consider absurd. This was started by a group called ‘improbable research’!

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