Could it be dislocated? It sounds like that might be a possibility too. Also, you might be able to get it to heal, if it's a break, by putting her in a cage that's small enough that she can stand up if she needs to, but not move around at all. That will keep her mostly immobile. You could also try using vet wrap or something to pull the leg right up to her belly and keep it there so she can't move it at all - there's a thread somewhere in the Emergencies section where someone did that for a rooster whose leg was broken when he was hit by a car and he had a full recovery.
But your best bet would be to bring her to a vet if you could, especially if it's just dislocated - they could just pop it back in.