They ask me before I go through the gate if I've had a hip replacement (no). Of course I am now in the over 75 group so I don't have to take off my shoes, which is probably why I'm asked the question. Evidently there were no metal parts to my knee surgery because they haven't shown up in the many times I've been through airport scanners in the past 40 years!

Anyway, if you now have metal parts, let the TSA folks know before you enter the scanner. They'll take you around with a hand wand so you don't set off any alarms!
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey