"It's a very difficult injury," Bulls coach Vinny Del Negro said on Wednesday. "It's very difficult to treat. He might rest for three weeks, he might rest for two months and come back and it's still bothering him. Rest will help usually, no question. But he's got to come back, fight through the pain.
"We'll give him a few weeks and hopefully he reacts better to that sooner. But that's the plan right now."
Noah, the Bulls' leading rebounder, has not played in the Bulls' past two games. On Friday, he played 27 minutes, the most since Feb. 3, against the Portland Trail Blazers.
Noah, in his third season, averages 10.7 points and 11.4 rebounds a game.
"I don't know if you do replace him," Del Negro said. "He's the second-leading rebounder in the whole NBA. And brings a lot of energy, a great spirit to the game for us. Gets us up possessions. Gets us out on the break. His offense has been developing all year and his development overall has been [good].
"It's a big loss, but other guys have to step up, and we're going to have to manage it. This biggest concern is rebounding the basketball. When we play bigger front lines, not having his length back there is an issue. Like I said, other guys have to step up and play well. And other guys have to pick their performance up until he gets back."
Nick Friedell covers the Bulls for ESPNChicago.com.