Basic first aid care would say to get her put her where she can be warm and not go in to shock. Call a vet and see if there are any pain meds you can give to poultry. You will probably either need to set it or maybe amputate it I would think. Unless you want her to drag around a dead leg. How did that happen?
Don't allow her to suffer if the situation is hopeless.
Boxers are like cookies you can't have just one :)