The Yankees announced that Feliciano had left rotator cuff surgery on Sept. 8, following an unsuccessful attempt to rehab a torn capsule.
The procedure will threaten his 2012 season as well, and Yankees manager Joe Girardi has raised the possibility that such a serious injury at this late stage could actually end Feliciano's career.
"I would be surprised if he pitched next year," Girardi said.
Feliciano, 35, signed a two-year, $8 million deal with the Yankees over the winter, crossing boroughs from the Mets.
He led the Major Leagues in relief outings in each of the last three seasons, setting a record with 266 total appearances over the three-year stretch.