User blog comment:Xilinoc/Ch. 576 - THE KILLERS HIGH 2/@comment-1338810-20140409140322

"...how the...

How would that even work? The title of "Kenpachi" and a Shinigami's Zanpakuto are two VERY different things to be passed on, good sir."

Because Isane made the statement that Zaraki had "inherited Unohana's name." Obviously that was talking about the title of Kenpachi, but it would have been a neat twist if the name he had inherited was Minazuki's for his (formerly) nameless Zanpakuto.