Avs defender Nikita Zadorov drove Kotkaniemi hard into the boards in the first period, and the center was flipped upside down while falling to the ice.
Kotkaniemi remained on the ice until the Canadiens' medical staff helped him to the dressing room. There was no penalty called on the play.
There's no update yet on a recovery timeline, but Habs head coach Claude Julien confirmed the sophomore won't travel with the team to New York for Friday's game versus the Rangers.
Julien also said Zadorov should be suspended for what he thought was a dirty hit.
Kotkaniemi previously missed seven games this season with a groin injury. The Finnish forward has struggled in his second NHL campaign, producing just five points in 22 contests.