Team spokesman Rob Raichlen says an MRI shows Rush tore his anterior cruciate ligament when his knee buckled during the first quarter of the Clippers' game at New Orleans on Tuesday night.
The injury occurred as Rush hopped into the lane to receive a pass and then crashed to the floor, holding his knee while grimacing in pain.
Rush also was fouled by Marcus Thornton on the play, but contact appeared to be minimal. Rush had entered as a reserve only two minutes before the injury occurred.
The Hornets won 110-102, handing the Clippers their fourth loss in five games.