Before Sharks center Joe Thornton heads into an uncertain offseason where he could be a free agent, he had more pressing business.

Thornton underwent surgery on a torn ACL and MCL in his left knee Monday to repair an injury that sidelined him less than two weeks before he returned to play the final four games of a first-round series loss to the Oilers.

"I've been in this business a long time," GM Doug Wilson said. "You see a player play with that type of injury tells you all you need to know about him."