The Phillies said an MRI of the five-time All-Star on Monday revealed tendinitis, bone inflammation and chondromalacia, which is pain due to irritation under the kneecap.
"We're still doing and researching who exactly we want to get opinions from," Philadelphia general manager Ruben Amaro Jr. said. "We're just trying to find the best people to treat this."
Utley wants to avoid surgery.
"I think that's the last resort at this point," he said. "We're going to try to exhaust every avenue prior to that."
The 32-year-old has had tendinitis in his knee at other times in his career, but the pain never persisted as long as at it has this spring training. Utley has been limited to pregame batting practice.
"Batting doesn't bother me. Playing catch doesn't bother me," Utley said. "The pounding on it — the jumping and the running — there's definitely pain there. Those are things that I've had in the past that have gone away with treatment, but right now it's not going away. We're just trying to do the best things we can to alleviate this."
Philadelphia doesn't have a timetable for Utley to play.
"For us this is a long-term thing," Amaro said. "Frankly I do not care if he's making opening day or not making opening day. For us, this is for him to be able to play long-term, long-term meaning through this year, through the next year, through the following. This is something we want to make sure that he's 100 percent when he gets on the field so we don't have any missteps beyond that."
Utley agreed to an $85 million, seven-year contract in January 2007. He was limited to a career-low 115 games last season following surgery in July to repair a torn tendon in his right thumb.
He had right hip surgery after the 2008 World Series and missed a month in the second half of the 2007 season after a right wrist operation.