Ekman-Larsson was defending against Avalanche forward Matt Duchene when the two collided and the Swedish blue-liner slid into the boards behind the Arizona net. He left the game and did not return.
It's unclear if the injury was caused by the original collision with Duchene or with the impact made with the boards.
The loss of Ekman-Larsson for any period of time would be a damaging blow to Arizona's already slim playoff hopes. The defenceman is their leading scorer with 49 points (19 goals, 30 assists).
With Monday's loss, the Coyotes remained 10 points out of the final wild-card spot in the Western Conference, with just 16 games left to play.