GREEN BAY, Wis. -- The most important offseason of Clay Matthews' career began with knee surgery.
A source told ESPN that the Green Bay Packers linebacker underwent a procedure that was described as "a cleanup" last week shortly after the season ended.
Matthews, the Packers' career sacks leader with 80, missed two games last season, but neither was because of a knee injury. In 14 games, he recorded 7.5 sacks -- his highest total since 2014.
The 31-year-old former Pro Bowler is entering a critical offseason. He's scheduled to make $11.4 million in salary and bonuses in the final season of his five-year, $66 million contract that still has him as one of the highest-paid linebackers in the league. The Packers could ask Matthews to restructure his deal this offseason.
Matthews' status with the team will be one of the first decisions for new general manager Brian Gutekunst.
Matthews, who missed one game last season because of a groin injury and another because of a hamstring injury, has not recorded a double-digit sack season since he had 11 in 2014.