Knuckle Popper?

Are you a knuckle popper? (I am.)

From Sarah Knapton:

The wince-inducing sound of knuckles cracking is caused by a small bubble building up in the fluid of the fingers then ‘popping ‘, scientists believe, and it could even be beneficial to health.

For decades researchers have debated what causes the unpleasant sound and argued about whether knuckle cracking could cause joint problems like arthritis.

Now a new study from the University of Alberta suggests that when muscle joints are pulled apart there forms a tiny cavity filled with gas which then collapses, creating a popping noise.

It takes a while for the gas to be re-dissolved in the slippery synovial fluid in the joints which explains why knuckles cannot be “re-cracked” immediately.

After watching cracking joints under an MRI scanner, the team also saw an unexpected white flash, which they believe could be water being drawn to the joint, which could even have a beneficial effect.

Previously scientists have calculated that the amount of force at work when you crack your knuckles has enough energy to cause damage to hard surfaces like bone, yet research also shows that habitual knuckle cracking does not appear to cause long-term harm.

Those conflicting results are something the researchers are planning to investigate next.