The 33-year-old right-hander from Japan was placed on the 10-day injured list Aug. 24 with right forearm tightness. Texas Rangers orthopedic surgeon Keith Meister performed the surgery.
Meister added an internal brace to the arm, a recent development in the Tommy John technique that could help speed the rate of recovery, which is traditionally at least a year. The Twins hope Maeda could return in nine to 12 months.
"There are never any guarantees, but we are pretty good on the medical side with rehabbing this kind of injury and getting guys back to full health,'' Twins manager Rocco Baldelli said.
Maeda was the runner-up in the American League Cy Young Award voting last season, when he went 6-1 with a 2.70 ERA in 11 starts. In 21 starts this season, Maeda was 6-5 with a 4.66 ERA.
Baldelli noted that the surgery addressed other issues in Maeda's arm that had been bothering the pitcher throughout his six-year MLB career, which began with a four-year stint with the Los Angeles Dodgers.
"Hopefully, when he's ready, we might see a version better than anything we've seen before, because they were able to go in there and clean some things up that he's been pitching with,'' Baldelli said. "This wasn't just a simple acute injury that he was dealing with. He's been pitching with some of this stuff for a while now. This gives him an opportunity to be at full strength going forward.''