Michalek has played in two games since Feb. 12. He tried to return and play through the injury, recording assists against the Toronto Maple Leafs on March 6 and the New York Rangers on March 8, but hasn't been in the lineup since.
In 15 games this season, Michalek has two goals and 10 points. He led the Senators with 35 goals last season and was third with 60 points.
The Senators' top-two scorers from last season, forward Jason Spezza and defenseman Erik Karlsson, also have been out of the lineup with long-term injuries.
We're buyers. We're committed to winning. That's what [owner Vinnie Viola] has said all along and what we've said all along. We want to win. We want to win a championship. We're putting the pieces together, step by step, and we're hopeful that Jaromir can lead these young guys to the promised land. It's a win-win for us.
— Panthers GM Dale Tallon on Jaromir Jagr, who he traded for from the Devils on Thursday