Why do bones pop?
If you put your fingers inside the fingers of the other palm, and turn both the palms back, you can hear a tickling sound. This is due to the knuckles popping. Joints, anywhere in the body, produce this cracking sound when the joint is stretched and bent. This sound comes out when the bubbles in the synovial fluid burst.
Joints are the connecting points of two separate bones, held together by connective tissues and ligaments. The joints in our bodies are surrounded by synovial fluid. When you feel stressed, and want to relax your muscles, you tend to stretch or bend your fingers. This causes the bones on either side of the joint to pull apart.
When bones are pulled apart, the capsule surrounding the joint, which is made of connective tissue, is also stretched. This capsule increases its volume by stretching. In turn,the volume of the joint also increases. When the volume increases, it is obvious that the pressure inside the joint decreases by nature. It is found that synovial fluid consists of gases like oxygen, nitrogen and carbon dioxide. When the pressure decreases in the synovial fluid, the gases dissolve in the fluid, and become less soluble.
This causes a bubble formation called cavitation in the synovial fluid. When the joints are stretched too far, then the bubbles burst, and generate a cracking sound. This sound is known as knuckle popping, or bone popping.
It takes 25-30 minutes for the gases to get re-dissolved into the fluid. During this period, you cannot hear any knuckle cracking sound. Again, after the gases get dissolved, cavitation can be created, and popping can be tried again.
Knuckle or bone cracking is not a serious problem according to some studies, but certain studies say that repetitive knuckle cracking might cause damage to the soft tissue of the joint. It may also lead to a weak grip.