She will have to remove her skirt/trousers along with her underwear but not her socks. Maybe she doesn't want the indignity of wearing an older pair of socks as she puts her legs into the Lloyd-Davies poles(more commonly known as stirrups).
You do not say why she is going, but Chilldoubt is probably on track, if she is having treatment which involves her having her legs in the stirrups for some while, she will have been told to take socks to stop her feet getting cold.