I think it would have had to be splinted right away, if thats what you were going to do.
I have had a few hens got trodden on by the big goats or the llama. A couple of weeks ago one of the silkie pullets was hopping, with one leg hanging. I have never had one that bad before, and considered culling her. Then someone told me to leave her, and see what happened ......I put her in a large indoor rabbit crate, plenty of bedding and food and water within reach. She wobbled round on one leg, took a few days to adjust her balance. Never stopped eating or drinking, and singing away to herself, so to my mind, she did not look miserable or in severe pain. Had that been the case, she would have been culled of course.
Over the last couple of days, she has been standing up - on both legs, and taking a few little steps round her little home!! I suspect she will always have a bad limp, but I have grown fond of her, watching her battle along this last fortnight. I have a little coop and run, and will put her with one of the ex battery hens in there, where she will be safe from any more clod hoppers in the field.