I find this odd that No one has responded to these posts of chewing on ones Knuckles!
I have been doing this since I was 9 years old, I am now 34, and my fingers look completely deformed, I have accepted this as one of those nervous things that I do, but I am interested in any therapy, and or procedure I can have done to make them look normal again.
Above all, I notice that this is a form of self mutilation, and I tend to do it when my mind races, or when I have idol time. I also do it out of compulsion.
I am researching perhaps hypnosis therapy, to correct the thought process that leads to me putting fingers in my mouth.
Once the habit is broken, I may look into surgery to correct anything that doesn't heal on its own.