why are my knuckles different?

i was rummaging through some of the straight dope classics, and came across http://www.straightdope.com/classics/a2_305b.html this, and i was entertained and undoubtably informed by it

I am indeed a fan of cracking knuckles, i do it to each knuckle at least 3-4 times a day (not to mention my elbows, shoulders, spine, jaw, ect.) and throughout the past year or so, i began to see that my joints (knuckles expecially) could bend about 20-30% more than they could before i had started cracking them, and to proove myself sane, i tested it on other subjects and found a simular pattern with cracking knuckles (those that cracked knuckles could bend their joints more, and those that didnt were a bit more inept to doing so)

I was wondering exactly why this has come about? is it something that wears down the tendants or bone or whatever prevents the joint from going so far? or is there another wierd reason to it?

a few people in my school have said that cracking your knuckles does cause something to wear down and years and years later to swell so you need surgery to fix them…and it’s apparently painful…

i’m not sure if it’s true, it’s just what everyone says to people cracking their knuckles these days… all i know is i’m not taking any chances and don’t crack them anymore…not on purpose anyways…