Markov, unable to put weight on his right leg, was helped off the ice in the first period Friday night in the Eastern Conference semifinals.
He was skating toward a loose puck in the corner when Penguins forward Matt Cooke leveled him with a hit at 11:46. No penalty was called on the hit.
Markov's glove flew high as he dropped to the ice. As several players held and grabbed each other at mid-ice, Markov remained down for several minutes before being helped to a runway leading to the Montreal dressing room.
The Canadiens did not say Saturday how long their top defenseman will be out. Game 2 of the Eastern Conference semifinal series is Sunday in Pittsburgh.
On March 7, Cooke's blindside hit badly injured Bruins forward Marc Savard, who suffered a Grade 2 concussion and only this week received clearance for game action.
Information from ESPN.com's Scott Burnside and The Associated Press was used in this report.