Is it bad to crack my knuckles?

Meera Mahesh

Whether it’s you, or one of your friends or family, we all know someone who loves and someone who hates the sound of knuckles being cracked. Whichever one it is, you may have wondered why knuckles make that sound at all, and whether it’s unhealthy to crack your knuckles. Let’s find out more about this.


What is a joint anyway?

Knuckles are the names of the joints in your fingers. A joint is a place in your body where two or more bones meet each other. You have 360 joints in your body, with some of the biggest being your shoulders, elbows, hips, and knees.


There are lots of different types of joints, and this means that you can move your body in different ways. For example, you can twist your arm, so that your palm can face both the sky as well as the ground, but if you try rotating one of your fingers like this without moving any other part of your arm, you’d find this impossible! This is because of the different ways the bones come together to form the joint. You find different joints in different places in the body. One type of joint is the ‘fibrous’ joint which joins all the bones of your skull together. You can’t move these joints at all, which is why you can only break your skull bones, and not dislocate them. The other types of joints are cartilaginous joints, which make up your spine (or backbone). These move a bit more freely than fibrous joints, but it’s synovial joints which move the most, like your elbow.


Have you noticed you can only ‘crack’ some of your joints?

This is because of the type of joint – only synovial joints can be cracked. These are joints that have a gap between the two bones, filled with a special fluid called synovial fluid. This fluid makes it easier to move your bones and makes sure they are protected and well supported. When you jump down the stairs, it’s the synovial fluid that acts like a pillow to absorb the shock when you land so you don’t get hurt. Synovial fluid is made up of lots of water, proteins from your blood, and dissolved gas.


There are several theories as to why synovial joints crack, but the most accepted one is that as you crack your finger, there is more space between the two bones. This makes all the gas in the synovial fluid leave the fluid to make a bubble. This bubble collapses on to itself, which is what we hear as the ‘cracking’ sound.


So now we know why your knuckles crack, you might be wondering whether it’s healthy to crack them. Although people assume that it is bad for you, the scientific evidence does not support this. One doctor, Donald Unger, famously cracked only the knuckles of his left hand every day for over 60 years but not the right hand to see if there would be any difference in the joint conditions that he got. Nothing happened to either hand. Even though this is not the most scientific study, it goes along with the consensus that it is not that bad to crack your knuckles. If you’re one of the people that loves to crack their knuckles, get cracking!