I think a class in basic human anatomy is in order for the writer for Yahoo! Style who seems to be a tad confused about the location of the Duchess of Cambridge’s knees:
Perhaps if she had looked at some photos on the site she works for she would have seen the location of a hemline and the duchess’s knees:
It looks like the hemline of the coat, at least, is above her knees. So, I’m guessing that her dress is above her knees, too.