GREEN BAY – Packers defensive lineman Muhammad Wilkerson needed surgery on his injured ankle on Sunday night in Washington, D.C., and did not return to Green Bay with the team.

Head Coach Mike McCarthy said on Monday that Wilkerson's injury was "significant," but he did not elaborate.

Following Sunday's 31-17 loss at FedExField, the Packers are also dealing with injuries to starting offensive lineman Bryan Bulaga (back) and Justin McCray (shoulder), while outside linebacker Nick Perry is in the concussion protocol.

McCarthy did not have any updates and said it could be until Wednesday or Thursday before the lineup at those spots for Sunday's home game vs. Buffalo takes shape.

"We're beat up coming out of the game," McCarthy said. "You look at the course of these first three weeks, they're battling like hell. We're going to have to see how it sorts out. (The injury report) will be part of our game-planning."

Discussion also continues this week on roughing-the-passer calls, which have frustrated Clay Matthews and the Packers.

McCarthy said he's been in communication with President/CEO Mark Murphy, who is on the league's competition committee, in search of more clarity to rules that the officials don't appear to be applying consistently.

Shortly before Matthews was flagged for another hit he felt was within the rules, Packers QB Aaron Rodgers was tossed down for a sack on which his helmet hit the ground.

"I think we can all safely say, without criticizing, the play with Aaron definitely could have warranted a flag," said McCarthy, who regretted getting as visibly upset on the sideline as he did after the Matthews call.