Markstrom was injured in Saturday's victory over the Boston Bruins. Thatcher Demko has taken over as Vancouver's starter and won his first start as the club's No. 1 on Tuesday in Montreal.
The Canucks also acquired Louis Domingue before the trade deadline for some insurance in goal.
Markstrom has been solid for the Canucks this season, posting a 23-16-4 record along with a .918 save percentage. He's an impending unrestricted free agent, although Benning has said he hopes to extend the 30-year-old netminder.
Vancouver enters Wednesday's slate of action in the second spot in the Pacific Division, tied with the third-place Edmonton Oilers at 74 points while holding a game in hand.