For a long time, people thought that Bouchard's nodes were caused by cracking your knuckles. There are people who do that quite a lot and I remember my teacher warning students in class not to do it, in case they develop arthritis when they get older.
Now I see that research has proved them completely wrong and that swollen nodes can happen to anyone.
I was also glad to see that apparently things like running don't cause it, although I'm not sure why being overweight can cause arthritis but running or putting stress on your joints by cracking them doesn't.
Maybe it is all in the kind of stress that your body responds to.