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.
When we started our journey we made a commitment to our fans to be relevant and to see the Chicago Blackhawks become the best professional hockey organization. There are not two finer symbols of that than Jonathan Toews and Patrick Kane. The commitment we have made to these incredible young men is equal to the commitment they have made to our team, our fans, our entire organization and the city of Chicago.
— Chicago Blackhawks owner Rocky Wirtz on signing Jonathan Toews and Patrick Kane to contract extensions