The 42-year-old left-hander, a likely future Hall of Famer, will require a four to five month rehabilitation period, the Braves said in a report on their Web site.
"I think four months is more realistic, and five months is a much more conservative timetable," Glavine said. "I'm confident from what I've heard from doctors and from what the MRIs have shown (that) four months is a much more realistic timetable."
Glavine has said he would pitch in 2009 if the Braves welcomed him back, mlb.com reported.
Doctors said Glavine has a partially torn tendon.
Orthopedic surgeon James Andrews in Birmingham, Ala., who examined Glavine Wednesday, said he will get a better understanding of the extent of damage when he operates.
Glavine is 305-203 in 22 major league seasons.
The pitcher went to the 15-day disabled list Friday, a day after he gave up seven earned runs and seven hits in four innings of an 11-7 loss to the Chicago Cubs.
Glavine complained of elbow soreness before he left the game.
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