User blog comment:Xilinoc/Ch. 553 - Frozen Cross/@comment-6342763-20131016153208/@comment-4458023-20131016153734

Well, if i may say, remember Isshin's bankai wears him out and puts a strain on his body and back, so to have an injury on his back would cancel out using his bankai, but daiguren hyorinmaru doesn't cost hitsugaya anything to use it