The 22-year-old Czech was injured after taking a crushing hit from Thrashers forward Evgeny Artyukhin in the first period of the Bruins' 4-0 win over the Thrashers on Tuesday night.
He was to be re-evaluated on Wednesday and again Thursday morning, but he likely will not play Thursday night.
The Bruins could use forward Brad Marchand, a healthy scratch the last three games, or they may make a call-up from Providence to replace Sobotka, who has four goals and five assists in 53 games this season.
