The center, who has 36 points (19 goals, 17 assists) in 51 games this season, is out indefinitely because of a lower-body injury sustained in the second period of a 3-2 win at the Minnesota Wild on Sunday, when he fell awkwardly during a face-off. Forward J.T. Compher will replace Kadri on the second line, playing between Valeri Nichushkin and right wing Andre Burakovsky.
The Avalanche, 7-1-0 in their past eight games, are in second place in the Central Division, three points behind the St. Louis Blues.
The Senators, trying to end a five-game winless streak (0-3-2), are 2-8-7 in their past 16 games. Ottawa is 15th in the Eastern Conference.