"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."