Hansen delivered a forearm to the back of Hossa's head during the third period of Chicago's 4-3 shootout victory that left the Blackhawks winger flat out on the ice before he returned to the locker room for the remainder of the game.
Hansen was assessed a minor penalty for roughing.
The incident was particularly unfortunate for Hossa, who was also knocked out of a playoff series against the Phoenix Coyotes last year after sustaining an illegal hit.
The Blackhawks said that Hossa appeared to be in better condition this time compared to the Phoenix hit, when he suffered a season-ending concussion.
Hansen had claimed that the hit came as a result of him pursuing the puck but after a hearing with the league, the NHL took action.