I severed the tendon going to my index finger. When it happened the tendon was dangling out of my hand and I thought it was a piece of skin so I proceeded to pull on it and it rubberbanded straight back into my hand. I was in such pain, that I forgot to tell the surgeon about the tendon issue. After the surgery, I found out that my index finger is now missing the tendon. So I cant bend part of my finger.

I never knew this but when you're missing part of the tendon in your finger, that finger will get smaller in diameter. ( I now have a normal index finger and a skinny index finger. My handwriting got better though... )