WASHINGTON -- Injuries have crippled the Nationals this season, and the situation grew even worse on Tuesday when the team announced that first baseman Nick Johnson would miss the rest of the year, following wrist surgery at the Mayo Clinic.

Johnson injured his right wrist on May 13 and was placed on the 15-day disabled list two days later with a torn tendon sheath, an injury first expected to keep him out four to six weeks.

But the pain didn't go away, and Johnson was evaluated on Monday by Dr. Richard Berger, a hand and wrist specialist at the Mayo Clinic. Berger performed arthroscopic surgery on Tuesday to evaluate the ulnar side of the wrist and had to repair a small split tear in a ligament there.

Team officials said Johnson is done for 2008, but expect him to be ready for Spring Training next year.

"I feel bad for Nick, because I know how much Nick loves to play and how important he is to our ballclub," said Nationals manager Manny Acta. "He loves to play. He's the ultimate professional."

Johnson played in just 38 games this season after missing all of 2007 after breaking his leg late the previous year in New York.

He was hitting .220 when he injured his wrist, but led the Nationals with a .415 on-base percentage, something that impressed Acta.

"Even when his batting average is not there, he's getting on base four out of 10 times, which sometimes a guy who's hitting .330 on your club is not doing," Acta said. "Defensively, he was brilliant this year. We're going to miss him."

The 29-year-old first baseman has battled injury problems throughout his career. He missed parts of 2003 (with the Yankees) and 2004 (in Montreal) due to injuries and lost the 2000 season in the Minors for the same reason.

"I feel bad for Nick and his family," general manager Jim Bowden said. "He's had a tough career of injuries, [and] this setback is almost amazing. But it's what's happened this year to our club, and we'll just have to overcome it. He'll work hard. We'll get him rehabbed and, hopefully, [he'll] be 100 percent by Spring Training."

The news that Johnson was done for the year saddened his teammates, who know how hard the first baseman worked to get ready for the season.

"It's frustrating for him, I'm sure," said third baseman Ryan Zimmerman. "But like he always does, he'll work through it, and I'm sure he'll be back. It's just weird. It's like it always happens to him."

Injuries have limited catcher Paul Lo Duca to just 23 games this season, and the veteran clearly was saddened when talking about Johnson's plight on Tuesday.

Lo Duca said Johnson sent him a message by text, but he didn't answer back because he just couldn't find the right words.

"I don't know what to say to him, to be honest with you," Lo Duca said. "I've been injured all year, and I'm finally getting back to healthy again. I can only imagine what he's going through. It's definitely a difficult situation for him. He's still young. He's still a great player. He's just been unlucky."

So have the Nationals, as both Acta and Bowden said. Lo Duca and Ronnie Belliard recently came off the disabled list, and the Nationals have seven more players on it -- including Zimmerman, closer Chad Cordero and others. Four players on the DL were in the Opening Day lineup.

Dmitri Young, last year's Comeback Player of the Year in the National League, will replace Johnson, but he also missed 40 games in April and May.

The Nationals now have made 16 disabled list moves involving 13 players -- and the season isn't even halfway finished yet.