Do you need special papers to go thru airport metal detectors if you have metal in your body?

I recently had spinal fusion surgery, and I have titanium rods and screws as well as a batery pack implanted in my back---never to be removed. When going thru an airport, I will surely set off the metal detector. Will I always have to give explanation of my hardware, or is there some kind of paper the doctor gives you? Whats the deal?
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Where does one get these "implant" cards? Is this something that the doctor gives out, or is it an airport thing???