CLEARWATER, Fla. -- How long until Chase Utley returns to the Phillies' lineup?

Nobody knows, but this much is clear: He is sidelined indefinitely with what the Phils call mild patellar tendinitis and chondromalacia. Utley had an MRI exam Monday, which also revealed bone inflammation. The Phillies and Utley are exploring alternative treatments and solutions after a cortisone injection Friday proved ineffective.

Surgery is an option, but the club said it is a last resort.

Utley is likely to open the season on the 15-day disabled list, but Phillies general manager Ruben Amaro Jr. said he expects him to play this season.

"We think he'll be healthy enough sooner rather than later," Amaro said.

Though the Phillies and Utley could not speak specifically about the next step in treatment -- they said they are still researching different methods -- they said they will not rush the process.

"My goal is to alleviate this as quickly as possible, but still keep in mind I have a career ahead of me," Utley said. "There's no black and white here. It's something you have to deal with. And obviously it's a little frustrating right now, but we have to look at the big picture and try to get this resolved, obviously quickly, but also be in good spirits for the long run."

"They can be fairly effective," Phillies head athletic trainer Scott Sheridan said of these potential treatments. "The problem is that nobody wants to take the time sometimes. That's the important thing -- that we do it the right way. That's where we're at."

Utley has had pain in his knee since before Spring Training started. The Phillies initially prescribed rest, but with no improvement, they administered the cortisone injection. The club said Utley has had knee issues in previous springs, but it always dissipated and never required a shot. Utley said, however, he has received injections in the knee before, although it could have been during the season.

Utley said he feels no pain in the knee when he takes batting practice or plays catch, which he continues to do. But he said the pounding his knee takes when he is running or fielding ground balls persists.

Utley has a reputation for playing through pain -- he played with an injured hip that required surgery following the 2008 World Series -- but this pain is too much to tolerate.

"He doesn't feel comfortable enough to be able to play," Amaro said. "If he could, knowing Chase, he would be playing. Frankly, rest might be the best option here.

"That's one of the reasons why we continue to do what we're doing right now, which is some of the rehab stuff Scott has been doing and [team physician Michael] Ciccotti has been doing with him, is rest and some of the other things that he's done. I think rest may be the best option here."

Wilson Valdez is Utley's likely replacement at second base. Amaro said he has no plans to fill the hole from outside the organization.

There are persistent rumors Philadelphia could trade for Texas' Michael Young, but the Phillies have little to no payroll flexibility. Young is owed $48 million over the next three seasons, which would require the Phils to shed payroll in order to add the veteran Rangers infielder.

Joe Blanton's name naturally pops up at these moments, because the Phillies looked to move him after they signed Cliff Lee to a five-year, $120 million contract. Blanton is owed $17 million over the next two seasons, but Amaro has said previously he expects the right-hander to be in the rotation to start the season.

If the Phillies truly believe Utley will be back at some point this season, they might go with what they have internally rather than swap pitching depth for a temporary solution. Valdez filled in admirably last season when Utley and Jimmy Rollins spent time on the DL, but the Phillies also have other infielders in camp such as Delwyn Young, Michael Martinez, Pete Orr, Josh Barfield and Brian Bocock.

"We're just trying to get him well," Amaro said of Utley. "That is our priority. We believe that he is going to be playing. We don't know exactly when he is going to be playing for us, but I expect him to be playing for us at some point -- hopefully in the early part of the season, maybe even the beginning of the season.

"Right now, I think we have the talent in here to go with, and that's where we're at."

What is troubling is that nobody knows how long it will take.

It could be a few weeks.

It could be a few months.

It could be longer.

"It really is unknown," Utley said. "I'm doing everything I can at this point to get back on the field. There is no timetable. We're not going to look for the short-term solution. I want to be smart about this and realize I have three years left under this contract to fulfill."

"Frankly, I do not care if he's making Opening Day, if he's not making Opening Day," Amaro said. "For us, this is for him to be able to play long term. Long term meaning through this year, through next year, through the following year. This is something that we want to make sure he's 100 percent when he gets on the field so that we don't have any missteps beyond that. That's really the goal here. That's why we've been holding him back so much."