...I have held the assumption that if the wrist was broken, then the connection would also be broken along with the ability to fell the uke, like trying pick up something with a broken spoon. Basically, I think that you can't throw uke or make him fall if you break his wrist outright.
I may be wrong, but I think you can still control uke's center once you've broken the wrist because it's still attached by way of sinew and muscle. It just becomes more fluid. Unless the part you're holding on to breaks off
I don't see how the connection is necessarily broken just because the bone(s) are separated.