Hopefully, she only has a sprain, not a broken leg, or especially not Mareks disease. But Mareks is a virus that some chickens can get. It can cause lameness, sometimes tumor, sometimes blindness or eye changes, and it may kill them. It strikes young chickens usually in the first year of life. I really don’t want you to worry too much about this being Mareks, but I just want to point out that her leg could be lame due to a disease, not just a broken bone or a sprain. When you have time, you might want to read this link about the disease:
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/