My main character has a metal arm (think the Winter Soldier? Or maybe Adam Jensen?) that is permanently attached to his body. His body is going through the growth stages similar to puberty and I know he'd have to get a new arm. However, I'm not sure how to go about showing that the arm no longer 'fits' him and that it is damaging his body because, unfortunately, bionic arms of that ilk don't exist in real life. Any ideas, guys?