Most of the titanium implants don't even register on the screening. I have plates and screws in my right ankle and a titanium right hip. Depends on how sentitive the settings are. And all that they'll do if you DO alarm is wand you after you go through. Just tell them about your ankle and you'll be fine.TSA is gonna love me!
I'm an attorney; I ALWAYS set off the metal detectors at the courthouses, and almost never at airports (which should tell you something about how sensitive/effective the airport detectors are).
I'll be getting metal implants in my neck in August; hitting the trifecta (neck, ankle, hip).