The myth that knuckle cracking causes arthritis is deeply ingrained, but it's not true! Scientists have proven that this habit is completely safe for your joints. There is no link to arthritis. The protagonist of this story is American physician Donald Unger. For 60 years, he cracked the knuckles of only one hand: his left. His right hand served as a control group. His experiment, begun in 1947, involved cracking the fingers of his left hand at least twice a day. Nearly 36,500 cracking sessions. The results were published in 1998 in the journal Arthritis & Rheumatism. The examination revealed no arthritis or other damage in either hand. The crunching sound itself is not the bones grinding together, but rather the bursting of gas bubbles (oxygen, nitrogen, carbon dioxide) in the synovial fluid of the joint. So, Mom, you can rest easy! Donald Unger even won the Ig Nobel Prize in 2009 for this research. Arthritis is an autoimmune or inflammatory disease that has nothing to do with popping.