The 28-year-old suffered the injury in Wednesday's Capital One Cup defeat at Burton and will now be missing from Harry Redknapp's squad for between six and nine months.
Faurlin signed a new one-year deal at Loftus Road in July having spent a portion of last season on loan at Palermo in an attempt to improve his fitness.
Redknapp, who may now look for another midfielder before the transfer window shuts on Monday, said the club will do all they can to help the player recover once again.
"We're all desperately saddened and disappointed for Ale," he said. "He is a great man and player, and he's suffered terribly bad luck over the last few years with injuries.
"We will, of course, do everything we can to support him and help him back on the road to recovery.
"It's a massive blow, he's a great lad, he's a special lad, but he will work so hard. He'll come back again I'm sure."