Ennis collided with Kirby Dach in the second period and was helped off the ice. He didn't return to the game - a 4-3 loss for the Oilers.
Ennis was acquired by the Oilers from the Ottawa Senators prior to the 2020 trade deadline in exchange for a fifth-round pick next year. The pending unrestricted free agent posted 37 points this season, including four in nine games after arriving in Edmonton.
The Oilers trail their best-of-five series 2-1 with Game 4 scheduled for Friday.