xs 2 I think most leg problems with hatchlings can be traced back to either temp (the majority) and genetics/quality of breeder and eggs.It's temperature related, I'm almost certain. I had the same experience with a styrofoam incubator. Have never had that happen since I bought a more expensive one.
It's not nature's way. I have never had a splayed leg under a broody silkie
It's not your fault. Styrofoam incubators are notoriously finicky, it seems even more so with the new LG 9300 (which I would bet money you are using). People can be successful with them, but they require much more attention than the more expensive incubators. I have a Brinsea Octagon 20. It's expensive, but well worth the money if you have a full time job and not a lot of time to keep a close eye on the incubator every day. There are people on here that get good results from LGs. AmyLynn is one, silkiefeet is another. Talk to those guys and they can give you some tips for more successful hatches in styrofoam