City's assistant manager Arthur Cox confirmed: "It's a grade three tear and I don't expect to see him again this season. It's very unfortunate because he has done very well since joining us."
That means that Van Buyten's 'tangle' with Alan Smith on Monday that resulted in a red card at Leeds will probably be his last moment of action in a City shirt.
Kevin Keegan has already said he believes that even if Van Buyten's club Marseille want to sell him in the summer that a bigger club will step in.