I bet you have just tried cracking your knuckles after reading this title, if not then you’re probably resisting the temptation now! It seems that giving ones knuckles a good old crack is strangely satisfying, and until recently the reason as to why this ‘cracking’ or ‘popping’ sound occurred was a little unclear. Researchers performed an MRI scan on a group of people’s knuckles in order to glean some understanding on the cause of this ‘cracking’ sound. The scan confirmed what many people previously thought, that the noise is made by trapped gas escaping from the joint spaces. The process of cracking knuckles involves stretching the joint spaces which in turn cause gas to rush into the space, and it is this that causes the ‘crack’ sound. Researchers now want to understand what happens in the joint after the crack in order to understand how it (if at all) implicates joint health.
BBC News, (2015). Scans reveal why knuckles go ‘crack’. Retrieved 20th April, 2015, from http://www.bbc.co.uk/newsround/32330824