Question
hi, i don't know if you're the right one to ask or not, but:

is it bad to "crack" your knuckles and/or other joints?  im only 16 and I tend to do it a lot.  it never hurts, if anything it feels good.  i broke my index finger about 5 mos. ago but now it's back to normal, and i crack it like any other finger.  what is this cracking, anyways?

Answer
Hi Greg,

You really shouldn't crack your knuckles regularly.  There is some speculation that it could cause the ligaments (bands that hold the bones together) to get loose...which leads to you feeling like you need to crack them...which leads to more losening, etc.

The sound itself is thought to be nitrogen gas:  like release from a suction.

Jen