LOS ANGELES — Los Angeles Lakers center Andrew Bynum might undergo exploratory arthroscopic surgery on his injured left knee if there is no significant improvement in the next three to four weeks.

Lakers spokesman John Black said Bynum was examined Wednesday by Dr. Steven Gecha in Princeton, N.J. Black said the team was told there had been some improvement in the 20-year-old center's knee, but Gecha's recommendation was exploratory surgery if there wasn't more in the upcoming weeks.

"I'm not surprised about it," Lakers coach Phil Jackson said, adding that it was only recently Bynum had said he felt pain-free.

"That's why the doctor said, 'Let's wait three weeks,"' Jackson said before the Lakers faced the Utah Jazz in Game 2 of their Western Conference semifinal series Wednesday night. "It's still touch and go. We'll address this more later."

Bynum hasn't played since injuring his knee Jan. 13 in the third quarter of a 100-99 victory over Memphis at Staples Center. He averaged 13.1 points, 10.2 rebounds and 2.1 blocked shots in 35 games.

The Lakers estimated the day after Bynum was injured that he would be sidelined 8 to 12 weeks. But Jackson said on April 21 that a return this season was remote, and Bynum said much the same thing last week.