My DD can’t go thru the scanner because she can’t walk. She gets screened in her wheelchair and in most cases, she keeps her shoes on, they do a patdown and do some swabbing of her shoes to check for explosives.
As was pointed out, the TSA agents cannot insist that anyone remove braces or medical equipment. You can remove it if you choose to do so, but they are not supposed to even ask you to remove it and the information on the TSA website tells passengers not to remove it.
http://www.tsa.gov/travelers/airtravel/specialneeds/editorial_1370.shtm
It sounds like your DD would not be able to walk by herself without the braces on. You are correct that you would not be able to help her walk thru. The metal in the braces may or may not make the scanner alarm if she walks thru.
If it doesn’t alarm, she would probably not get any additional screening. If it does alarm, she would get the same kind of screening as my DD does.
Here is what we do.
DH goes ahead thru screening and then DD goes thru - she bypasses the scanner since she can’t get out of her wheelchair. One of the TSA agents normally pushes her thru the scanner bypass as DH is going thru the scanner since they are allowed to move between the screened and unscreened areas.
DH stays nearby while DD is getting screened. He can be close - up to about 3 feet - but is not allowed to touch DD until after she has been screened (the fear is that someone who has been thru the scanner and has completed screening could remove something from the person in the wheelchair and get it by the screeners that way).
After my DH has gone thru screening and is with DD, I start sending our belongings thru the X-ray machine. Once they are all inside the X-ray machine, I go thru the scanner.
That way, we always have one person on each side of security and DH is available to be near DD.
If it is only you and your DD, I would do as bookwormed suggested and go thru first, followed by your DD. Once you have been screened, you can go back to the ‘unscreened’ side, but unscreened people can’t go thru to the other side.
So, prepare your DD that you will be nearby and will be watching, but will not be allowed to touch her and she will not be allowed to touch you until after the TSA agent says she is done.
Prepare your DD that the agent will be touching her and her KAFOs with gloved hands. The swabbing will be done with a small piece of cloth held by what looks like a tweezers. The agent will rub that across surfaces like parts of her KAFOs and her shoes. They will make your DD wait without being touched by you, while they get the reading done on the swabs, which can take a few minutes. The more she can relax and try to do what they ask her to do, the faster they will be done.