Harper will need surgery to repair a torn ulnar collateral ligament in the thumb, a source confirms, and Harper could be out for around two months.
ESPN first reported that Harper would need surgery.
Harper injured the thumb sliding into third base on a triple in Friday night's win over the Padres. He remained in the game initially, but came out after the thumb started to swell up.
The Nationals placed Harper on the 15-day disabled list yesterday, initially calling the injury a sprained thumb. They hoped that a second round of tests would reveal no further damage, but after Harper visited hand specialist Dr. Thomas Graham at the Cleveland Clinic today, the diagnosis was confirmed to be a ligament tear.
Harper missed 31 games last season due to bursitis in his left knee, and he required offseason surgery to clean out the knee. He entered spring training bulked up and excited to put last year's injury-plagued campaign behind him, and now a month into the season, he lands on the DL for an extended stretch yet again.
Without Harper, manager Matt Williams will rely on a platoon of Nate McLouth and Kevin Frandsen in left field, with Tyler Moore also getting a chance to play there a bit, as well.
McLouth was signed to a two-year, $10.75 million deal this offseason to provide the Nats a versatile, proven fourth outfielder who could step in should one of the starters go down with an injury. That's what has obviously happened here, and now McLouth will get a good bit of playing time in Harper's stead.
McLouth is off to a slow start to the season offensively (4-for-34), but he homered yesterday and has said that he feels he's in a pretty good place at the plate, just isn't getting much to show for it.
The Nats are already without third baseman Ryan Zimmerman (fractured thumb), catcher Wilson Ramos (broken hamate bone), right-hander Doug Fister (lat strain) and reserve outfielder Scott Hairston (oblique strain). They lost center fielder Denard Span for a week earlier this season due to a concussion.
Now they'll be without Harper, one of their top all-around players, for around two months.