Lee was hurt in the fourth quarter of Saturday's loss to the Denver Nuggets in Game 1 of the teams' first-round Western Conference playoff series.
The extent of the injury was revealed after a magnetic resonance imaging exam, resulting in a key blow to Golden State's playoff hopes.
Lee was hurt when he landed hard on his right hip following a foul by Denver's JaVale McGee.
The 6-foot-9 Lee led the NBA with 56 point/rebound double-doubles this season, averaging 18.5 points, 11.2 rebounds and 3.5 assists per game.
Notable deaths of 2014 [PHOTOS]