The All-Star defenseman got hurt while taking a shot Saturday during the Bruins' 2-1 home victory over the Washington Capitals. He left the game for a while but returned in time to score the tying goal in the closing minutes.
"It's not long-term, it's short-term," Bruins coach Claude Julien said after the Bruins' 1-0 shootout loss to the Rangers. "It's hard for me to give you a timetable right now, but we'll probably go day by day."
Boston's next game is Tuesday at Ottawa.
The 6-foot-9 Chara has scored a career-high 48 points this season and has matched his best NHL totals with 16 goals and 32 assists in 68 games. He hadn't missed any contests this season before Sunday.
Chara, 30, was replaced in the Bruins lineup against the Rangers by defenseman Matt Lashoff, recalled Saturday from Providence (AHL).