Baby legs are not straight because they’ve been curled up tight in the uterus. As your baby stands and jumps on his legs, he will strengthen muscles and straighten bones. Special shoes, bars, and casts are rarely needed.
There are many more things that are normal in the newborn period–too many for most lists and books. Your pediatrician doesn’t expect you to learn everything about pediatrics in a few weeks, so call if you have any questions about your new baby.