Hartenstein (Achilles) has been ruled out for Thursday's game against the Nuggets, Stefan Bondy of the New York Post reports.
Hartenstein was questionable for Thursday's matchup, but he'll be unavailable for a second consecutive game due to an Achilles injury. Jericho Sims will likely draw another start for the Knicks on Thursday, while Hartenstein's next chance to return will be Saturday against Miami.