Utley isn't expected to return until the September stretch drive, or longer than the Phillies had hoped.
"Yeah, this hurts," Philadelphia manager Charlie Manuel said Thursday.
The operation was performed Thursday in New York, three days after one of the majors' best all-around infielders was injured trying to stretch a single into a double. He was put on the disabled list Tuesday with a sprained ligament, and doctors later determined part of the ligament was detached from a bone.
"They reattached that -- I would call that severe," Phillies athletic trainer Scott Sheridan said.
Utley, 31, must wear a splint on the thumb for five weeks before he begins rehabilitation. Utley and the Phillies will get a better idea exactly how long he will be sidelined once the stitches are removed from the thumb.
"Can we get through it? Yeah, we can get through it," Manuel said. "I'm going to put it to you like this: We're going to get through it. I look at our team and what I preach is we've got to play. I don't give a damn who we play with, we've got to come here to win."
The Phillies also will be without third baseman Placido Polanco for about a month with an inflamed left elbow, although of the two doctors who examined him determined surgery was necessary. Polanco has been bothered by the injury since April 21, and the team determined a lengthy shutdown was needed for the injury to heal.
"He's had rest in the past, and obviously it wasn't enough," Sheridan said.
While the Phillies will try to get by with utility infielders Greg Dobbs, Juan Castro, Wilson Valdez and Brian Bocock for now, general manager Ruben Amaro is believed to be looking at available infielders with experience.
"What we got right now is what we're work with. ... There's different ways of replacing somebody besides going and getting someone in a trade," Manuel said. "People on your team stepping up, or some guy comes along and he ends up having a career year, you can do it that way."
Replacing Utley for a sustained stretch would be difficult for any team, even if Manuel was encouraged when role players Dane Sardinha, Brian Schneider and Valdez all homered this week. The Phillies also are without catcher Carlos Ruiz, who has been out since June 19 with a concussion.
Utley is leading the fan voting for a starting spot in the All-Star Game later this month. He is hitting .277 with 11 home runs and 37 RBI this season. He had a combined 64 homers and 197 RBI as the Phillies reached the World Series -- winning it in 2008 -- the previous two seasons.
The Phillies went into Thursday night's game in Pittsburgh trailing NL East leader Atlanta by 3½ games and second-place New York by two games. They went 13-13 in June after beginning the month a half-game out of the division lead.