Gallagher, 23, has missed the last 17 games after undergoing surgery on two fractured fingers on his left hand.
Gallagher was injured during his team’s Nov. 22 win over the New York Islanders, when his left hand was struck as he blocked a shot from defenseman Johnny Boychuk.
At the time of his injury, Gallagher was tied for 23rd in the NHL with 19 points, and ranked 16th in the league with 70 shots on goal.
Montreal was 16–4–2 when Gallagher was injured, and has since fallen to 21–15–3 in his absence.
The Canadiens meet the Bruins at Gillette Stadium on Friday at 1 p.m. ET in the Winter Classic.