The news comes after star winger Mikko Rantanen was ruled week-to-week with a lower-body injury last week.
It's not clear when Landeskog, the Avs' captain, was injured.
The 27-year-old Landeskog has three goals and four assists in 11 games.
The Avalanche lead the Central Division with 17 points. They are an early favorite to go deep into the playoffs, in large part based on what some consider the best top line in hockey.