Allen underwent biceps surgery following Saturday's win over the Raiders, Mark Kaboly of The Athletic reports.
While the Steelers haven't confirmed that Allen had surgery, the linebacker's recent Instagram stories would seem to indicate that he had a procedure following Saturday's contest. Expect the Steelers to provide an update on the 26-year-old's status within the next few days, but the fact that he had surgery clouds his availability for the final two games of the season.