Here are some links about slipped tendon with pictures of chick chairs:
https://www.backyardchickens.com/articles/slipped-tendons-chick-chairs-blindness-and-caring-for-the-special-needs-chick.72163/
https://www.backyardchickens.com/forum/uploads/6612_chick_chair.jpg
Wrapping the legs can sometimes cause more damage due to it getting too tight and interrupting circulation. Have you started some vitamins including B2 riboflavin, or human B complex? I would try the B complex 1/4 tablet a day or other vitamins. It can be difficult to know which it is (slipped...