User blog comment:Xilinoc/Ch. 568. Hear. Fear. Here 2/@comment-1604252-20140212213631/@comment-26420452-20140212221117

In chapter 517, Kirinji tells Unohana that she can't fully recover them through her techniques.

Byakyuya essentially went through a grinding machine and Renji was kicked across the Seireitei (think a little about the distance). I don't know what happened to Rukia, but she was bandaged allover, but apparently was less wounded than the other two, because for a little bit, she was conscious. The only one with comparable injuries was Kira, but he must've died because it's been so many chapters and no one has mentioned him.

And don't forget that the Royal Guard operates on the Soul King's order, so basically all of this is on a whim, sort of.