Gunnarsson was injured in a puck battle with Los Angeles Kings forward Gabriel Vilardi along the boards behind the Blues' net with 9:20 remaining in the second period. He left the ice with help from teammates and did not return.
Gunnarsson is currently undergoing further orthopedic evaluation and imaging to determine the full extent of the injury.
"It's disappointing for sure, and really disappointining for him, I'm sure," said Blues Head Coach Craig Berube. "An injury like that is tough. It's tough to see a teammate and player go down like that with that injury. I feel bad for him. We're losing a great teammate, a great guy, and a real good hockey player for us."
