Several of you asked us if cracking your knuckles causes arthritis, so we put our Verify team on it.
Scientists used an MRI machine to record knuckle cracks as they happened. In the video, you see a dark gray spot form between the joints; that's a cavity created in the synovial fluid, an egg white-like substance that reduces friction in your joints.
The creation of that cavity is what makes the cracking sound. And while it might look a little startling, researchers say it doesn't actually do any harm.
They're backed up by more research. A radiologist from the University of California, Davis found the same thing. Dr. Robert Boutin studied a group of people who crack their knuckles and a group who doesn't. He says there wasn't any difference in the health of their hands.