Yes - this frequently happens to me (I have a large pin in my left leg). But there is no consistency. Sometimes I set the alarm off and sometimes not - in the same airport. Sometimes they ask to see the scars and sometimes they don't. I also have to wear special shoes from the same accident and I don't even wait to be asked now - I just take 'em off before I get to the scanner and stick 'em on the belt. I do try to be helpful so I'm minded to always wear shorts and short socks together with a T Shirt that explains the extend of my metal parts. Wouldn't make any difference though - some of 'em just have it in for you . . .!