Knuckle cracking doesn't cause arthritis. A doctor tested it for 60 years.

Question on this card

Where does the sound of knuckle cracking come from?

1. Bones rubbing together
2. A gas bubble forming in the joint fluid
3. A tendon snapping
4. Cartilage breaking

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This card belongs to the topic Body & Health. Every card is short, cites a source and can be saved – due ones come back by themselves later.

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