"The reality is that Joel probably won't be ready for Opening Day," general manager Neal Huntington said. "Is it May 1? Is it June 1? We'll know more as we get more doctor information."
Tests so far have shown no structural damage, and surgery has not yet been a point of discussion with Hanrahan.
"Hopefully it won't be anything that lingers all year," Hanrahan said. "Hopefully we can get it taken care of now. If I miss two weeks to a month, that's better than missing a whole year."
Along with Evan Meek, Hanrahan was expected to be the Pirates' seventh- and eighth-inning setup men to Brendan Donnelly and closer Octavio Dotel. Hanrahan earned the opportunity to pitch in late-inning situations after some solid outings with Pittsburgh last season. He posted a 1.72 ERA and struck out 37 in 33 relief appearances (31 1/3 innings) for the Pirates following a midseason trade from Washington.
The Pirates feel they have some internal options to fill the void left with the injury to Hanrahan.
"We're not panicking about our bullpen," Huntington said. "There are still some guys out there that we have talked to, but at this point we are content with our bullpen. We think we have enough options internally to fill the middle of our bullpen.
The Pirates also announced that infielder Ramon Vazquez underwent surgery on his right knee in November, 2009. He is expected to partake in monitored spring training action and is expected to be healthy by Opening Day.