The exact nature of Graham's surgery is unknown. But he will likely have plenty of time to recover before summer camps and training camp. The Saints revealed late in the 2012 season that Graham had been fighting through the nagging injury for the entire season - though he never missed a game or practice because of the wrist injury.
Like Rob Gronkowski, Graham's per game numbers slipped (from 12.3 PPG in 2011 to 10.1 PPG in 2012). He was battling this wrist injury throughout the season, so there's a good possibility that he'll bounce back in 2013. He holds extra value in PPR formats.