The procedure was needed to clear out debris around the area. Michalek will be out indefinitely while recovering.
Michalek has been dealing with lingering issues with his knee, which forced him to miss 10 games beginning on Feb. 13 against the Pittsburgh Penguins. On March 6, the 28-year-old forward was able to return to the lineup to face the Toronto Maple Leafs and was available two nights later against the New York Rangers.
After practicing the Sunday after the Rangers game, Michalek was unable to skate the next day, which prompted head coach Paul MacLean to announce that he had suffered a setback and was considered day-to-day.
Michalek had already stated that he was going to require surgery on the knee after the season. Once the setback occurred, speculation began about the surgery needing to occur in the immediate future. That ultimately turned out to be the case.
Earlier on Tuesday, Bruce Garrioch of the Ottawa Sun published a story that stated that the Senators were hopeful that Michalek would be back in time for the playoffs if he did opt to have the surgery.