Poor thing.
To niece:
Make your uncle work his butt off and wait on you hand and foot. It's all he's good for. He told me personally that he was entirely at your disposal, and that if you got better quickly, he'd buy you a pony named Sparkles.
Seriously, I hope she gets well soon. It's terrible being cooped up when you're a kid (though I'd gladly trade places with her).