Is it possible that the calf laid in a weird position inside the cow, and / or had its back or hips were knocked out of joint during the birth, beside having a possible lack of selenium?
I have seen human babies born with "creaked" necks because they laid in a wierd position inside momma before they were born, and it was known they were laying in a wierd position before birth. (they ended up fine though)
If the calf can move around much I would put her and momma cow in a small pasture by themselves and see what happens. Wouldn't leave her there over night though, dogs might chew her up.
If she can move around a bit it might help her.
Had a couple of bow legged calves years ago.When they were kicked out of the barn to just run and "be calves" , over a couple of weeks their legs straightened right up. They needed the sunshine and exercise. Not saying it would help this calf, but it might.
Nite Hawk