MINNEAPOLIS -- Josh Willingham underwent successful arthroscopic surgery on his left meniscus on Wednesday, the Twins announced. Team physician John Steubs performed the operation.
Willingham, who also has a bone bruise in the knee, is expected to be out four to six weeks, but general manager Terry Ryan doesn't want to put a timetable on his return.
"He had a scope this morning," Ryan said. "Everything went well. They repaired the torn meniscus in the left knee. So we'll go from there. He'll be out for a while. I'm not going to put a timeframe or a limit on it. He's certainly going to extend beyond the 15 days. I'm not sure how far, though."
Willingham, 34, is hitting .224/.356/.398 with 10 homers and 37 RBIs in 70 games after batting .260 with a career-high 35 homers and 110 RBIs last season.
But manager Ron Gardenhire said it's unclear just how much Willingham's knee affected him at the plate. Willingham has maintained that the knee only bothered him while running.
"I think Josh is the only person that can tell you that," Gardenhire said. "We've asked him about it -- 'Is it bothering you when you're swinging?' And he'll say no. But if you're physically not able to turn and spin on your legs, it probably does, but he would never admit to that; he's not an excuse-maker."
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.