I've got a chick that looks very simular to yours now. She too has a broken leg, but it isn't apparent exactly where. She holds it up like yours. She hops around on that one leg and balances herself using her wings. I won't cull, but prefer to treat and hopefully she will make it in the flock. I do however plan on getting another chick to keep her company. Better for her and better for me too. Best of luck
Jan
Jan