The center will have surgery next week and is expected to be ready for training camp next season. He will not play the final four games this season, beginning against the Vancouver Canucks on Thursday (9 p.m. ET; ESPN+, SN, NHL.TV).
"He did battle through it," Flames coach Darryl Sutter said. "He's done it not for two or three games. He's done it for the last 20 games. It tells you about his character and desire and give you what he's got. I've said that all along about him. Sean tried to do everything that I asked him to do and he did it with pain. I give him a lot of credit."
Monahan scored an NHL career-low 28 points (10 goals, 18 assists) in 50 games this season, the first time in his eight NHL seasons that he didn't score at least 22 goals. He missed the final seven games of the 2017-18 regular season and had wrist, groin and two hernia surgeries.
"He's a teammate I've been close with ever since I've been a part of the Flames," forward Milan Lucic said. "He battled through a lot just to get through this season, fighting with the hip injury that he's had. A lot of people can say what they want to say about him, but at the end of the day he's one of the guys who will battle through anything to help his teammates and try to help them be in the best position that they can. He is a really good character guy and a great teammate. I wish him nothing but the best with his surgery and rehab and recovery."
Calgary (23-26-3) is fifth in the seven-team Scotia North Division and will not qualify for the Stanley Cup Playoffs.
NHL.com independent correspondent Aaron Vickers contributed to this report
