It has puzzled scientists for over 100 years but now they appear to have cracked it: what, exactly, is it that causes that wince-inducing sound when you pop your knuckles?
Love it or loathe it, knuckle-cracking is very common. Earlier studies have established that not all joints can be cracked, and that – for that those that can – the act can’t be repeated for another 20 minutes.
