Chick with splay leg? Help!

[Bauermeister.farm]

Hello all,
One of our poor polish chicks is having a problem with her leg and I need some guidance. She is almost three weeks old and about a week ago we realized that she was limping a bit, so after doing some research I thought she might have just injured it running or something. I kept a close eye on her for a few days and it seemed to get better as she could still walk and run and eat and drink, but it started to get worse and I noticed that one leg was starting to go out to one side (See pictures). Her back is now leaning to one side as well, and we decided it might be splay leg, so she has been wearing a band/straw harness to try and bring her legs in. I am worried though because even with the harness, her foot is out to the side at an odd angle and her back is still crooked. She does not seem to be in pain, she does not drag on her belly like some chicks with splay leg, and she seems to be eating and drinking fine. If you can see from the pictures below, her foot goes out to the side completely even with the brace on.

Is she too old for it to be corrected? How long should we keep the harness on? Is it something different than splay leg? Thanks for the help!