Josh Harrellson was scheduled to undergo surgery to repair his fractured right wrist on Tuesday, according to the team.
He suffered the injury Saturday night against the Nuggets and is expected to be sidelined for six weeks.
After practice on Monday, Mike D'Antoni was blown away with the rookie's toughness while he was stricken with the injury, which occurred when Harrellson fell to the ground in the latter part of the game.
"Can you believe he's out? Here's a guy who played four minutes with a broken wrist, takes a 3-point shot," he said. "But he's a tough guy. You hate to lose him because I thought he was playing really well. But that's good for the future. He'll be back after All-Star break some time."
On Tuesday morning, Harrellson tweeted from his verified account: "Woke up this morning ate a bowl of nails! Then had glass for a snack! Now Im headed to surgery soon! I have ice in my veins! #CountryStrong"
Jerome Jordan was called up from the D-League on Monday, likely to replace Harrellson as the Knicks' third-string center. Harrellson had played in all 18 games, averaging 5.2 points and 4.3 rebounds in 18 minutes, while shooting 35.6 percent (16-for-45) from downtown.
Information from ESPNNewYork.com's Jared Zwerling was used in this report