Hedman, 23, will have the surgery on Tuesday.
"You feel for Hedman," Lightning head coach Jon Cooper said, according to the team's website. "Our team, we've got some depth back there. Injuries happen. You really feel for him. He's come out of the gate so strong. He's poised just to build on the year he had last year. Now, he might be sidelined here for a little bit."
In five games this season, Hedman has seven points (three goals and four assists), tied with Steven Stamkos for the team lead. He was the second pick in the 2009 draft.
Hedman is averaging nearly 20 minutes of ice time per game, fourth most among Lightning skaters. He skates alongside Anton Stralman on the team's top defensive pairing.
- Brad Rowland