"He felt something, and they looked at it," Reds general manager Walt Jocketty said. "He came in the next day and saw there was probably an issue."
An MRI exam confirmed the meniscus tear. The surgery was held up until team medical director Dr. Tim Kremchek could get to town and perform the operation. A small flap of the cartilage was removed during the arthroscopic procedure.
"[Kremchek] said everything went well," Jocketty said. "It was an easy repair, a quick repair. It was a very minor surgery."
Over 32 starts in 2013, Latos was 14-7 with a 3.16 ERA. In 210 2/3 innings, he allowed 197 hits and struck out 187 batters with 58 walks. He became the team's de facto ace while Johnny Cueto was on the disabled list. After the season, Latos needed surgery to remove bone chips from his right elbow, and his rehab and throwing program had been going smoothly.
What isn't known yet is whether Latos will be ready by Opening Day, on March 31.
"We'll just see how he progresses," Jocketty said. "Right now, I can't say whether it would or not. We don't think so, but we'll see."
The Reds, who added depth behind their five-man rotation during the offseason, could have an opening for free-agent signings like Chien-Ming Wang or Jeff Francis. Both were signed to Minor League deals and are non-roster invites. Rookie David Holmberg was acquired in a trade from the D-backs in December.
Reds broadcaster Chris Welsh, who pitched in the big leagues from 1981-86, noted during Jocketty's session with reporters that he once had his meniscus repaired.
"I think I pitched on it the 22nd day, in a game," Welsh said.
"And that was 50 years ago. Technology has advanced," Jocketty joked.
Jocketty downplayed worries over Latos' status. The Reds will certainly need his contribution to contend in the National League Central again.
"Is it unfortunate? Yeah, but it's not something that we are overly concerned about," Jocketty said. "I didn't want to start the camp off with an injury before we got started. Sometimes, it happens."