This is straight from the band:
"Sorry to everyone in Philly for having to cancel last minute. As everyone knows, Sonny had two surgeries where they cut your vocal chords very slightly in order to smooth them out and have them be a 100%.
This surgery requires a lot of rest and absolutely no talking during recovery, but since we had a commitment to be on this Atreyu tour and the second surgery was last minute... his rest wasn't sufficient, and more rest is absolutely needed.
We plan on continuing the tour in a very unique way. Sonny will be out at the shows resting, and he will be playing guitar the entire set. Craig, the singer for Chiodos, offered to step up and help us out and sing the set for Sonny... what a guy... as well as a few other friends from Chiodos and Every Time I Die.
So make sure you come out and see the pandaemonium, and we are sorry for this, but Sonny's health is an absolute priority and this is the only way to get him singing top notch this winter in time for the recording of the new record."