The Royals had announced on Tuesday that Perez had a lateral meniscus tear; the surgery will take place in the next few days at a location to be determined.
Perez, 21, met with reporters on Wednesday afternoon in the clubhouse, leaning on crutches and answering questions with the catcher who'll likely replace him, Brayan Pena, acting as translator.
"I'm very sad. It's my first year, and I was very motivated, and it's very painful. But hopefully I can bounce back and I'll be fine," said Perez, who was injured while warming up pitcher Jonathan Sanchez prior to Tuesday's Cactus League game against the Reds.
"I was catching Sanchez in the bullpen, and I felt something funny in my knee, but I didn't expect that it was something very dangerous," he said. "But right now they told me that it was way more than I thought it was. It was a pitch inside, so I was trying to move in, and that's when my knee tweaked. My spike got stuck, and ... my knee moved out of place."
The club said that no timetable will be set for Perez's return until the medical team performing the surgery determines the severity of the injury. The meniscus cushions the knee between the femur and the tibia, and Perez's tear is on the outside. That type of surgery typically requires several weeks' recovery before a player is game-ready.
Although his knee was sore, Perez was able to get into his crouch, and he caught Sanchez in the first inning but then was taken out of the game. Head athletic trainer Nick Kenney sent Perez for an MRI, which revealed the injury.
Perez said he'd never had problems with the knee.
"Usually meniscus injuries are very fixable, and there's really not any long-term ill-effects, assuming the surgery goes well and the rehab goes well," general manager Dayton Moore said. "We know what a great worker Salvy is, and he'll do everything in his power to get back and ready to go."
The Royals have dodged the injury bullet with two of their other prize youngsters, first baseman Eric Hosmer and third baseman Mike Moustakas, both of whom hit the dirt in Monday's game. Hosmer tweaked his right shoulder and Moustakas was drilled in the right knee by a pitch, but both were pronounced OK. Perez isn't as fortunate.
"It's really a freaky thing, but the important thing is [that] he's going to get it fixed, and hopefully it's not too severe when they get in there and we can get him back playing at some point in time this season," Moore said.
The loss of Perez means that the Royals will rely on Pena as their starting catcher, at least early in the season, or try to make a deal for an experienced backstop. Pena is regarded as a good hitter, but he does not have the defensive or game-calling credentials of Perez.
Last season, Pena shared catching duties with Matt Treanor, who was obtained from the Rangers at the end of Spring Training when the Royals decided that Lucas May had shortcomings behind the plate. In addition, veteran Jason Kendall's recovery from shoulder surgery was not coming along as fast as expected.
Pena, a switch-hitter, batted .248 in 72 games and was recognized as improving his defensive skills throughout the year. Treanor sustained a concussion in a home-plate collision on July 30 at Cleveland and never returned. Manny Pina came up briefly, but Perez was summoned on Aug. 10, and Treanor subsequently was sold back to the Rangers. Treanor signed this winter with the Dodgers.
Pina is the third catcher on the Royals' 40-man roster, but he underwent surgery on his right knee on Feb. 27 in Kansas City after tearing the meniscus while catching in batting practice on Feb. 22. He is expected to be out for the rest of Spring Training and possibly beyond.
Moore said that the Royals are scanning the marketplace for more catching depth.
"With Manny Pina going down in almost the exact same situation, we were trying to find some depth already, so we're going to have to continue to search for solutions and more depth there," he said.
Manager Ned Yost noted that the injuries to Perez and Pina are strangely similar in how they happened. Both were reaching for pitches, and both caught their spikes in the dirt, twisting their knees.
"When it happened to Manny, he went down right away," Yost said. "Sal didn't even hardly flinch. He came in and said, 'My knee's a little sore.' The trainer checked him, he was squatting fine, and Sal said, 'I'm fine, time to go.' When he came back in, he was having problems. ... He could squat fine, but when he tried to straighten it out, he was having some pain."
Among the other catchers in camp are Cody Clark and Max Ramirez, both of whom have considerable Triple-A experience.
Clark, 30, took Perez's place in Tuesday's game, and had two hits. Last season he played 51 games for Triple-A Omaha and batted .233 as he shared catching duties with Pina, May and, briefly, Perez. He's been a solid backup catcher in the organization since 2007.
Ramirez, 27, has grabbed attention in Cactus League play by slamming three home runs, and he leads the team in RBIs, with seven. A right-handed hitter, he's played 45 games in the Majors, with the Rangers, with a .217 average. He's caught in Triple-A since 2008.
But aside from them, the catching cupboard in the organization is rather bare, experience-wise.
The Royals thought so much of Perez that, after just 39 games of big league time, they signed him to a five-year, $7 million guaranteed contract through 2016, with club options for the following three seasons. If all the options are exercised and all the performance bonuses are achieved, the deal could be worth $26.75 million.
During his seven-week stay in the Majors last year, Perez earned respect from the pitchers for his ability to analyze opposing hitters, manage a game, cover the position and throw. In addition, he hit much better than anticipated -- .331 with 21 RBIs and 13 extra-base hits, including three home runs.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.