Everyone knows that flexing a joint can cause it to ‘crack’ or ‘pop’ just like cracking a knuckle. It’s a common sensation that isn’t painful, but we were never able to ever see what was actually happening in real time.

Scientests from the University of Alberta have for the first time imaged a joint cracking in real time after decades of debating if the pop is created by a bubble’s formation or collapse.

“It’s a little bit like forming a vacuum. As the joint surfaces suddenly separate, there is no more fluid available to fill the increasing joint volume, so a cavity is created…”,” – Professor Greg Kawchuk, the lead researcher. 

Check out the vision and cringe a bit when it pops!

Crack away everybody! Crack away!

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Source: Kawchuk GN, Fryer J, Jaremko JL, Zeng H, Rowe L, Thompson R (2015) Real-Time Visualization of Joint Cavitation. PLoS ONE 10(4): e0119470. doi:10.1371/journal.pone.0119470

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