Here is an article that has a cute sock chick slingpicture:
https://www.backyardchickens.com/articles/slipped-tendons-chick-chairs-blindness-and-caring-for-the-special-needs-chick.72163/
First you need to make sure what is wrong with her legs, before trying splinting or leg hobbles. A hobble should only be used for splay legs, where the legs are too far apart. Has she been getting around normally eating and drinking out of the feeders and drinkers? You may want to do some...