Portland center Joel Przybilla suffered a ruptured right patella tendon and dislocated patella in Tuesday night's game against Dallas.
Przybilla suffered the injury in the first quarter after jumping for a rebound.
The Blazers began the game with just 11 healthy players and announced during the game that Przybilla would be out indefinitely.
Przybilla is averaging 4.1 points and 7.9 rebounds per game.