Either way Hanrahan is expected to miss at least two months.
"A healthy Joel Hanrahan getting injured is a blow for anyone,'' Red Sox manager John Farrell said, "and a guy who's been a very successful pitcher, I don't know that you can necessarily just replace a guy of his ability and talents.
"But regardless of the injuries we're dealing with right now, our expectation and our level of play shouldn't be compromised by that. That's the expectation here, to go out every night to prepare and put a game together to win.''
Pitcher Jose De La Torre has been called up from Triple-A Pawtucket to take Hanrahan's place.
With both Hanrahan and Andrew Bailey on the DL, Farrell has named Junichi Tazawa the closer.
In nine appearances this season, Hanrahan has a 9.82 ERA, 2.18 WHIP and four saves.
Copyright 2013 ABC News Radio