you can try to slip it back into place and then splint it using my foam technique. this might work.
take a block of foam as wide as the chick's body. make a slice from top to bottom on each side where the chicks legs line up. ideally your block of foam is the same height as measureed from your chick's belly to the top of it's feet. aline the leg to the correct position, slip one into each side of the block and then duct tape around the block with the legs incased inside and feet sticking out bottom. then tape this whole unit to the inside of a bowl to keep the chick up right. you may have to set up a food and water bar for the chick to eat from. I did this with a day old chick and only had to do it 12 hours, then the chick was back to using it's leg (mine was spraddle, I know yours is not but I hope this helps) and do it sooner then later because the longer it's out, the less chance this will work.
