‘This is a common question I get asked over the dinner table,” says Kimme Hyrich, a rheumatologist and professor of epidemiology at the University of Manchester. And it’s no wonder – as many as 54% of us are habitual knuckle crackers, regularly making those distinctive popping noises as we manipulate the joints.
“The knuckle joint is a very tight space and there’s a little bit of fluid in it. When people crack their knuckles, they very temporarily enlarge the space,” says Hyrich. “The pressure drops and gas that’s dissolved in that fluid forms bubbles – and it’s the bursting of those bubbles that causes the sound.”
