In a release on its Web site, the team said the 30-minute procedure was performed in New York on Wednesday by New York Mets medical director Dr. David Altchek. The surgery removed some cartilage debris and smoothed some rough spots on the underside of Bynum's kneecap.
Bynum's injury initially was called a partial dislocation and a bone bruise.
He was jurt in a contest against Memphis on Jan. 13 and, despite his desire to play in the post-season, Altchek examined him on April 10 and declined to clear him.
Before the injury, the 7-footer was averaging 13.1 points and 10.2 rebounds in 35 games.
"In three months, he should be 100 percent and ready to play," Lakers coach Phil Jackson told the Los Angeles Daily News.
He is expected to make a full recovery by the start of next season's training camp.