Is cracking your knuckles bad?

For years there has been disagreement among scientists about what actually causes knuckle cracking.

Now, researchers say the familiar sound is caused by the popping of a small bubble of gas in the fingers, and have been able to see what is happening inside the joint.

Greg Kawchuk is professor of rehabilitation medicine at the University of Alberta and lead author of the research and says the research could help improve joint health care and the design of new materials.