For some people cracking the knuckles is a regular habit, while for others it brings an amazing relief.
It is proven that 25-54 % of the people crack their knuckles. However, there are some old beliefs that this harms your joints, causing arthritis.
A group of scientists finally decided to study this old belief and the results showed that arthritis, or joint inflammation, is in no way associated with the knuckle-cracking.
In the joints there is a special lubrication liquid and small air bubbles. It is the bubbles that make the cracking sound, not your joints and bones.
In short, here is how the whole process goes:
The synovial fluid contains carbon dioxide, nitrogen and oxygen, so the knuckle-cracking actually decreases the pressure in your joints. Then the joints come back in place, the synovial fluid as well, and this produces the cracking sound.
This means, contrary to all beliefs, the returning of the joints in place is not harmful or dangerous. This is why the knuckle-cracking brings a comfortable relief for many people.
A survey in 2010 proved that arthritis developed in 18% of the people who had this habit, and in 21.5% of people who did not have it.
Which means, do not listen to your grandparents and crack your knuckles if it brings a relief to you!