A statement from the team said there is no time frame for his return:
"While Andrew and the 76ers are both eager for him to resume game play as soon as possible, given the long regular season and the playoffs, the team intends to act with caution as to the date of his return," read a statement issued by the team.
The 76ers will host the Denver Nuggets at 7 p.m. Wednesday.
Bynum has been battling knee problems for the last month. He had Orthokine therapy on the knee in late September and hasn't played since.
As of two weeks ago, it was expected that Bynum would play in the season opener.
Bynum was traded from the Los Angeles Lakers to the 76ers over the summer in a four-team deal. Bynum was one of the biggest pieces in the trade, as well as Magic center Dwight Howard going to the Lakers.
Bynum, who turned 25 on Saturday, had his best season of his career last year. He averaged 18.7 points and 11.8 rebounds per game. He's played in 392 games in seven seasons with the Lakers.