I would try to make a splint of some sort and put it on the leg. Popsicle sticks work great, i use electrical tape to keep it on because it stays on, and doesn't hurt them when you take it off. Was the chick born that way? if so, sometimes you can fix it if it is early enough.
I had a chick once that was born that way, and nothing was done to try fix it, when i got the chick, it was too late to fix. However i kept the chick anyways and made ramps so it could get to and fro easily. sadly, she got sick and died, so who knows how long she would have lived.