make sure that the surface they are on is not slippery.
we had a splayed leg chick with our first hatch..... probably didn't treat it properly and we had to cull him aged 4 weeks

we had another one with third batch, we immediately taped legs together (hip width apart) and used to handle him to stand in our hands and let him run around on the carpet......(a bit like physio i suppose)
he's fine now wouldn't know there was a problem
HTH
Mx