Buildup of fat around finger joints

Ever since junior high, I began to crack my knuckles along with my middle finger joints. I know that cracking the joints result in minimal to no damage at all to the joints since you're just popping air bubbles... but for some reason, the lateral bands around my finger's middle joint began to grow. My index and middle finger began to widen and soon enough, it seemed as if there was a buildup of fat around my middle joints. I feel no pain at all in my joints and I can move my fingers around freely. On the other hand, the buildup of fat is causing me to lose my sense of touch on my index and middle finger since it's covering my joints. (It feels as if there's an extra layer of fat around my joints) I got my fingers checked out and took an x-ray along with a CT scan... and my doctor told me that there was nothing wrong with my joints. In conclusion, there was SOMETHING covering my joints.. and my surgeon had no idea what it was. After my operation, my surgeon told me that he didn't find anything out of the ordinary... so even after undergoing surgery.. my question is still standing. What exactly is the thing that is surrounding my finger's middle joint? My other fingers are completely fine except for my right hand's index and middle finger. My doctor even suggested plastic surgery to get my finger back to normal but I still want to know my diagnosis. Why and how did I get all this extra buildup of fat/tissue around my joint?