Maikel Franco's recovery from a bruised left wrist had stalled, so the Phillies sent their third baseman in for an MRI exam on Monday. The test revealed a small fracture - a diagnosis last week's X-ray had missed - that could prematurely end the 22-year-old's promising rookie campaign.

The Phillies do not believe the injury will affect Franco in the future. The fracture is of the "very small, non-displaced" variety, according to general manager Ruben Amaro Jr. Franco is wearing a splint and will continue to do so for about two to three weeks. He was placed on the 15-day disabled list retroactive to Aug. 12, the day he took a pitch off the wrist in Phoenix.

"I don't know whether he's going to be able to be back by the end of the year or not, but we're going to be cautious with him," Amaro said. "We have to be as cautious as we can. He's too important to us. We'll see how he progresses."

Franco's first three months as a major-league regular offered a glimpse of the Phillies' future. He was named National League rookie of the month for June. Franco compiled an impressive .830 on-base plus slugging percentage over 296 at-bats, slugged 13 homers, and drove in 48 runs.

Cesar Hernandez and Andres Blanco will man third base in Franco's absence. Unless second baseman Chase Utley is traded by the end of the month, Hernandez will likely be the team's primary third baseman for the season's final seven weeks. Cody Asche will remain in left field, though Amaro said the team may have Asche field ground balls to be ready in case a double-switch sends him back to the hot corner.

The Phillies promoted versatile outfielder Aaron Altherr from triple-A Lehigh Valley to fill Franco's spot on the active roster. Altherr, always known more for his defense than his offense, took a big step in the right direction with his bat this season. He will spell centerfielder Odubel Herrera and also garner playing time in right field and perhaps some in left.

On Tuesday, Herrera batted out the third spot typically occupied by Franco.

"It's going to be tough missing that righthanded bat, especially in the lineup," interim manager Pete Mackanin said of Franco. "But we're going to do everything we can to get through it and just keep battling. There's nothing we can do about it."

The original diagnosis on Franco's wrist was a contusion. He was hit by a Jeremy Hellickson fastball in the first inning of the Phillies' 13-1 loss to the Arizona Diamondbacks. Franco was out of the lineup the next four games but had been expected back as early as Tuesday. He was not available to speak to the media.

"It's a big blow," Amaro said. "We want to have one of our better young players [in the lineup]. He's having a heck of a year for us. He's been playing great and [he was] obviously a pretty strong force in the middle of the lineup for us. But you can't do anything about it. A guy got hit and you've got to deal with it."