"They have not given me a timeline on Clay," Packers coach Mike McCarthy said Friday about Matthews' return.
Matthews had surgery the next day to have pins placed in his hand to repair what was diagnosed as a Bennett's fracture. He had the pins removed Nov. 4 and returned for the Nov. 10 game against the Philadelphia Eagles.
He wore a hard, protective cast that covered his entire right hand for one game and wore a smaller cast after that.
After Matthews hurt his thumb again Sunday on a sack of Steelers quarterback Ben Roethlisberger, McCarthy said it was a similar injury.
The four-time Pro Bowl selection leads the Packers with 7.5 sacks despite missing four games following his first injury. He was ruled out for Sunday's game against the Chicago Bears, and if the timeline is similar to his first injury, he probably could not play before the Super Bowl on Feb. 2, if the Packers were to make it that far.
"Obviously he's not happy," Packers outside linebackers coach Kevin Greene said. "He's not a happy camper. I mean, he's a professional; he understands that's the nature of the game. It's a bad luck deal."
The Packers will rely heavily on Mike Neal and Nick Perry in Matthews' absence. Neal (abdomen) and Perry (foot) both were held out of practice Friday but were listed as probable for Sunday's game. The only other outside linebackers on the roster are rookies Andy Mulumba and Nate Palmer.
Palmer has been inactive the past five games.