Why does 'cracking' your fingers cause deformity?

I know there is a bubble or pocket of gas in them… why does ‘cracking’ them cause them to swell/grow deformed?

Unca Cece covers this in “What’s actually cracking when you crack your knuckles?” at: http://www.straightdope.com/classics/a2_305b.html wherein he states that it’s generally believed that cracking your knuckles does not normally cause damage, although it may aggravate certain conditions. If you are getting swelling or deformity I would see a doctor.

Thanks for the link. Cleared it up a bit. There is some disconformity(prominently in the ‘pointer finger’ knuckles), but I am stopping, this is day 6 today and I have noticed it healing a bit. If it does not get better in a few weeks, then I will go see a doctor. Thanks again