B767 CREW WAS ADVISED THEY CAUSED BLAST DAMAGE AND PERSONAL INJURY ON TAXI OUT IN ORD.

Narrative

DURING CRUISE; WE RECEIVED AN ACARS MESSAGE FROM DISPATCH STATING THAT DURING OUR PUSHBACK AT ORD; WE HAD OVERTURNED A CART AND CAUSED MINOR INJURIES. THE CAPT AND I WERE VERY SURPRISED TO READ THIS MESSAGE. AFTER REVIEWING THE DISPATCHERS COMMENTS; WE REALIZED WHAT COULD HAVE HAPPENED. UPON RECEIVING PUSHBACK CLRNC; WE WERE INSTRUCTED TO PUSH 'TAIL S' FOR A N TAXI OUT OF THE GATE. THIS WAS THE FIRST TIME THE CAPT; OR MYSELF; TAXIED N OUT OF THE GATES. AFTER SALUTE AND RELEASE FROM GUIDANCE; WE WERE INSTRUCTED BY RAMP CTL TO TRANSITION TO THE LINE AND FOLLOW AN A320 WHICH WAS ABEAM US AND LAST IN LINE. THE CAPT STARTED TO MOVE; BUT REALIZED THAT HE NEEDED TO WAIT FOR THE LINE; AND THE A320 TO MOVE IN ORDER TO FOLLOW HIM BECAUSE OF THE ANGLE WE HAD. HE FELT UNCOMFORTABLE BLOCKING. AFTER THE LINE MOVED; THE CAPT PROCEEDED TO TAXI; AND BECAUSE OF THE TURN HE HAD TO DO; IT TOOK A WHILE FOR OUR AIRPLANE TO MOVE AFTER PWR APPLICATION. I DON'T BELIEVE ANY EXCESSIVE PWR WAS USED; BUT I WAS LOOKING OUT THE WINDOW FOR TFC AND DID NOT SEE THE N1 GAUGES.