CINCINNATI -- It could be weeks. It could be months.

The Phillies said they do not know how much time Chase Utley and Placido Polanco will miss because of a sprained right thumb and an injured left elbow, respectively. They just know they are on the 15-day disabled list and will be sorely missed, the latest casualties on a team that now has seven players on the DL.

The Phillies called up Greg Dobbs and Brian Bocock to take their places on the 25-man roster, but losing Utley and Polanco clearly leaves a major hole in the lineup. Utley had hit .367 with one home run and 11 RBIs in his past 13 games and is arguably the best second baseman in baseball. Polanco had hit .318 with five homers and 27 RBIs for the season.

"We're a good team," said Phillies right fielder Jayson Werth, asked how the Phillies can survive. "We have faith in each other. We've been here before. We're resilient. We lost Jimmy [Rollins] in '08. We lost Chase in '07. We lost J-Roll this year. We're still where we're at. We play the [National League] East a lot in September."

Utley sprained the ulnar collateral ligament of his right thumb in Monday's 7-3 loss to the Cincinnati Reds at Great American Ball Park. Utley had a MRI on Tuesday morning in Cincinnati, but returned to Philadelphia on Tuesday afternoon and will undergo further testing Wednesday. The Phillies said once they know the severity of the sprain, they will know how to treat it. It could require surgery, although Phillies head athletic trainer Scott Sheridan said that would not necessarily mean a longer stint on the DL.

"Look back at Chase's fracture of his hand," said Sheridan, referring to the broken hand that kept Utley out for a month in 2007. "We decided to pin that. If we didn't pin it, it could have been four weeks. When we did pin it, it was four weeks. Again, we've got to get better information. That's the biggest question going forward. How do you treat it?"

Sheridan said there remain some questions on the grading of the sprain -- a Grade 1 is the least severe, a Grade 3 is the most severe -- and until trainers know the grading, they cannot recommend a treatment for it.

Polanco has been bothered with inflammation in his left elbow since a pitch hit him there April 21. He received cortisone injections May 31 and Sunday, but the latest shot did not take like they had hoped. The Phillies and Polanco said they thought he could be back in the lineup Tuesday, but that changed late Monday night.

"We weren't satisfied with the way he responded to the treatment," Sheridan said.

Polanco also returned to Philadelphia on Tuesday and was scheduled to have a MRI in the afternoon. A prior X-ray revealed no fracture but showed a bone spur that had been there for some time. An earlier MRI also showed the spur.

"The question is, why is it so persistent?" Sheridan said. "You would expect if you treat it with anti-inflammatories and the types of things we've done with it that it should respond. And it's not. I think it's time to put him on the DL, rest him and get some better answers."

Polanco said Monday that surgery was a possibility.

Sherdian said the Phillies expect to know more about Utley's and Polanco's timetables Wednesday. At the very earliest, Utley could return July 15 against the Chicago Cubs at Wrigley Field. Polanco, who has not played since Friday, could return July 11 against the Cincinnati Reds at Citizens Bank Park, the final game before the All-Star break.

The time Utley and Polanco miss could impact the Phillies' desire to make a trade. The performance of their substitutes -- Dobbs, Wilson Valdez, Juan Castro, etc. -- also will influence that decision. The Phillies acquired Tadahito Iguchi from the Chicago White Sox in 2007 after Utley broke his right hand and missed a month. It paid dividends, as Iguchi hit .301 with two homers and eight RBIs in 27 games as Utley's full-time replacement, helping the Phillies win their first NL East championship since 1993.

"We're always looking to get better," Phillies assistant general manager Scott Proefrock said. "Our focus may be a little different than it was, but we're willing explore whatever options are available. But the main thing is finding out the length of both Polly's and Chase's stays on the DL, and that we don't know just yet.

"Quite frankly, we've got a bunch of good players on this team. We've got four guys who were All-Stars last year. We've got a couple former MVPs. A former Cy Young winner. A couple 20-game winners. A World Series MVP. The cupboard is not bare. We're still a good team."

There are infielders available, if the Phillies choose to pursue one. But do they have enough to get one?

The Orioles are shopping second baseman Ty Wigginton, who entered Wednesday hitting .266 with 13 homers, 40 RBIs and an .823 OPS. Wigginton makes $3.5 million and will become a free agent after the season. The Reds released infielder Chris Burke from Triple-A Indianapolis this weekend. He was hitting .238 with five homers and 26 RBIs.

The D-backs could move second baseman Kelly Johnson, who is hitting .261 with 13 homers and 35 RBIs. The Indians released second baseman Mark Grudzielanek earlier this season, and he remains unsigned. He was hitting .273 with 11 RBIs in 30 games. The Royals have Willie Bloomquist and Chris Getz in reserve. Rangers infielder Joaquin Arias is out of options and could be had in a trade. Second baseman Josh Barfield is hitting .305 with Triple-A Portland. The Padres could move him because they have him only for infield depth.

In the meantime, the Phillies have Dobbs and Bocock filling out the roster.

The Phillies outrighted Dobbs to Triple-A Lehigh Valley last Wednesday after they designated him for assignment June 22. He went 2-for-17 in four games with Lehigh Valley after hitting just .152 with the Phillies.

Bocock was hitting just .179 with one homer and 12 RBIs in 65 games with Lehigh Valley. The Phillies had hoped to call up infielder Cody Ransom, but Proefrock said Ransom has a balky knee.

"We didn't want to call up a player that may have a health issue," Proefrock said. "We didn't feel comfortable bringing him up until it's resolved."

The Phillies have injuries even with their injury replacements. It has been that kind of season. Utley and Polanco join Carlos Ruiz, J.A. Happ, Ryan Madson, Chad Durbin and Antonio Bastardo on the DL. The roster has six players who have spent time this season in Lehigh Valley: Dobbs, Bocock, Valdez, Dane Sardinha, Nelson Figueroa and Mike Zagurski.

"I hope we get [Polanco] back in a couple weeks," Werth said. "Chase seems like he's going to be out for a while. Guys are just going to have to pick it up."