The 28-year-old is staring at a five- or six-month absence following shoulder surgery on Wednesday. Drewiske suffered the injury on Sept. 18 at training camp and was originally diagnosed to miss four weeks.
Drewiske was acquired from the Los Angeles Kings in early April and signed a two-year contract extension with Montreal in June.
The Wisconsin native appeared in nine regular-season games for the Canadiens and posted seven points and a plus-3 rating in a combined 29 games with Montreal and the Kings. Drewiske was a healthy scratch during the playoffs.
Montreal’s defence is still minus newcomer Douglas Murray (upper body) and Alexei Emelin (right knee) so Jarred Tinordi and Nathan Beaulieu are expected to remain with the NHL club at least until they return.
Drewiske has five goals and 25 points in 135 NHL regular-season games.
In other injury news, Canadiens forward Max Pacioretty underwent tests Wednesday after sustaining a lower-body injury in Tuesday’s 3-0 win at Winnipeg.