The Knicks announced that Noah underwent arthroscopic surgery on his left knee to remove a loose body on Monday afternoon and will be re-evaluated in three to four weeks.
The 6-foot-11 Noah had surgery on the same knee during the 2014 offseason, but Monday's procedure was due to a new injury, a source told ESPN's Ramona Shelburne.
The Vertical first reported that Noah was likely to have surgery.
Knicks coach Jeff Hornacek said Monday that Noah first felt the effects of the injury after the All-Star break.
While Noah is not expected to return this season, Hornacek said the Knicks still hoped that he would. A source with knowledge of the surgery said Noah should be clear within the team's timetable, barring setbacks or the Knicks' change in plan toward the end of the season.
The Knicks signed Noah to a four-year, $72 million contract over the summer with the hopes that he could be a defensive anchor for the club. Noah, 32, has performed well below expectations, missing time throughout the season because of a hamstring injury.
Noah is averaging 5.0 points and 8.8 rebounds in 46 games (all starts) this season.
Hornacek said the Knicks were satisfied with what they got from Noah when healthy.
"You think back at some of the games, he was rebounding at a high clip, probably one of the highest in the league per minutes," Hornacek said of Noah, who was eighth in the NBA in rebounds per minute among centers. "That's what we expected from him. We expected the defensive talk, him to anchor the back there and really talk to guys. He was doing that. We think he can get there."
Still, Hornacek stopped short of committing to having Noah start at center next season. Willy Hernangomez, Kristaps Porzingis and Kyle O'Quinn are all potential candidates for the starting center spot, along with Noah, entering next season.