Is there a disease that causes the knee to hyper extend completely backwards?

Is there a disease that causes the knee to hyper extend completely backwards?I just saw a video with a romanian boy who had his knee bent 100% in the wrong direction. http://www.youtube.com/watch?v=bvL_DGjGuhA at 3:30 in this video- you'll be able to see this phenomenon.

What in the world is that?

- Sydney
I HAVE no FREGGIN idea that was really odd , I think it happened when he was a baby

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