"We feel it's patellar tendinitis," Amaro said. "Could it be more than that? Perhaps. I just, right now . . . that's what we have."
The Phillies and Utley should know more in the coming days when the cortisone shot takes effect. If the inflammation can be reduced and the pain alleviated, then perhaps the tendinitis can be maintained with extra care.
"If not, we'll have to look more intently on it to see what the story is," Amaro said.
No one, not the general manager or the second baseman, would close the door on this injury being more serious than originally diagnosed.
Utley has been prevented from running or fielding drills since the diagnosis of tendinitis a week ago. In his place, five players have started games at second base, and nonroster utility man Delwyn Young has started the last three.
"The whole goal for me is to try to get this fixed as soon as possible but also keep it in perspective," Utley said. "I have to keep it right for the long haul as well. I think we're making the right progressions."
Utley, who has experienced the tendinitis in his knee before, said it has never lasted this long. The chronic nature of the condition could worsen as Utley, 32, ages.
"I've had it maybe in terms of pain here and there," Utley said. "But this is lingering longer than it has in the past. So with that said, there is a little bit of level of concern. But I think we're doing the right things to try to get it better."
Utley said he has wondered if it could be worse, but doctors have not told him anything to indicate that. Amaro said the MRI done on Utley's knee Feb. 26 showed no structural damage. The team is "still piecing this together," he said.
"I think we have an idea of what's causing it; it's just not progressing," Amaro said.
The cortisone shot is a short-term solution designed to attack the inflammation in the affected area. More shots are a possibility during the season, but repeated injections can cause damage. Placido Polanco had at least three cortisone shots last season. Amaro did not rule out more for Utley.
Last season offered many examples of how baseball players have handled differing bouts with patellar tendinitis. Oakland outfielder Ryan Sweeney had surgery in late July last season and didn't play again. Seattle outfielder Milton Bradley played his last game July 26 and had surgery in August that ended his season.
Others played through it. Texas slugger Josh Hamilton had two cortisone shots during the 2010 season to help him play with patellar tendinitis. He ended up as the American League's MVP. Detroit third baseman Brandon Inge played through the condition all season - with diminished results - and had offseason surgery.
Utley has played through his share of undisclosed pain before, but when asked whether he could play through this current injury, he was very clear.
"I don't think at this point I'd be much help to our team or to myself," Utley said. "But the goal is to get this better. There's still three weeks left in spring training and probably 190 games left to go in the season. So we'll do what's best for the team and myself."
Contact staff writer Matt Gelb at email@example.com. Follow him on Twitter at twitter.com/magelb