(Al Behrman/AP)

Nationals catcher Wilson Ramos will require surgery to repair a torn anterior cruciate ligament in his right knee, Manager Davey Johnson said. The full severity and complexity of the injury is not yet known, Johnson said, but Ramos will miss most of, if not all of, the remainder of the season.

Ramos, 24, is a primary piece of the Nationals’ future, the catcher they acquired in a 2010 trade and “our backstop for the next 10 years,” General Manager Mike Rizzo said. This winter, Ramos endured a harrowing kidnapping episode in his native Venezuela. He arrived for the season with steely grace, grateful to be unharmed and eager to move on with his promising career.

After a strong start to his second full season, Ramos now must recover from a devastating injury.

“It hasn’t been a very good year for him,” Johnson said. “I was telling him earlier, if he didn’t have some bad luck, he wouldn’t have no luck.”

Jesus Flores will replace Ramos as the Nationals’ starting catcher. He has played frequently this year, batting .200/.256/.229 in 13 games. Flores, 27, became the Nationals’ everyday catcher in 2009, only to miss almost two full years after a foul tip off his right shoulder led ultimately to a torn labrum.

“I’ve been in that position before,” Flores said. “I feel ready for it. I’m going to keep helping the team win. I feel very confident I can do my job.”

The Nationals called up Sandy Leon, 23, from Class AA Harrisburg as his backup. Leon is perhaps the best defensive catcher in the organization, strong-armed and “an outstanding reciever,” Johnson said.

While chasing a passed ball in the seventh inning last night, Ramos caught a spike in the grass and twisted his right knee. He writhed on the ground and had to be helped off the field by trainers. Immediately, the Nationals feared Ramos had been seriously injured. He went for an MRI after the game, and the Nationals had little hope for good news.

While Ramos had showed signs of regression defensively, he had been one of the Nationals’ most consistent hitters. He clobbered his third home run of the season Friday night, a 409-foot blast to center. Ramos was hitting .265 with a .752 OPS, and his .354 on-base percentage ranked ninth among major league catchers.

“Wilson’s done such a good job,” second baseman Danny Espinosa said Saturday night. “Obviously everyone knows how good he is defensively, and offensively he’s hitting the crap out of the ball. To lose Wilson, that’d be a big blow. That’d be horrible.”

Ramos’s injury adds to the Nationals’ nearly unfathomable list of significant injuries. Ramos becomes the ninth regular to land on the disabled list, joining cleanup hitter Michael Morse, right fielder Jayson Werth and closer Drew Storen among the high-impact, long-term losses.

The Nationals have also played without their third baseman (Ryan Zimmerman), their best utility man (Mark DeRosa), their set-up man and back-up closer (Brad Lidge), their projected fifth starter (Chien-Ming Wang) and their center fielder (Rick Ankiel).

Through it all, the Nationals have gone 21-12 and surged to first place in the National League East. Now they’ll have to overcome another blow.

“We got to start eating bananas or something, change our luck,” Johnson said. “We’ve had more than our fair share of players going down.”