A few weeks ago my girlfriend had to travel (to an event for my family, poor thing) with a plastic ankle brace. LAX-OKC and back.

I wasn't in LAX with her, but she said they ETD swabbed her brace in LAX.

I watched her go through in OKC. She refused to take off her moderate-soled sneakers after they "suggested" it (LAX T7 did not tell her to take her shoes off) and told OKC the refusal was because of her ankle injury while pointing at the bulge of the brace. She did not set off the WTMD even with the brace, and the brace was invisible enough under her jeans that TSA probably would not have noticed it if she hadn't mentioned it. TSA sent her to secondary, swabbed her shoes, and then swabbed her brace. (In series--she had to sit there while they swabbed one shoe, tested, swabbed other shoe, tested, swabbed the brace, tested.)

I seriously question why TSA swabbed the brace (which was under her pants, quite small in mass, and did not set off the WTMD) other than as retaliation for not playing shoe carnival. They did not pat down or wand her body; had they done so I would have had a blank complaint form ready.

Good luck.

As a postscript, it amazes me how much more irritating it is to watch people you care about get hassled (or retaliated against) by TSA than to go through it oneself. I've experienced this both with my Mother (watched her get SSSS-treatment for daring to fly on a one-way ticket) and my girlfriend, and after both experiences I was more upset than I have ever been after my own encounters (which admittedly have been mostly neutral or positive).