Chara will be re-evaluated in four weeks.
The Athletic's Fluto Shinzawa reported Friday that the initial timetable was expected to be four to six weeks.
Missing games is not something Chara is accustomed to. He has appeared in 70-plus games 15 times during his two decades in the league, including in each of the past three seasons. The last time he missed extended action was in 2014-15, when he was limited to 63 games.
He has not missed more than 19 games in a season since becoming a regular in 2000-01, as the Boston Globe points out.
The 41-year-old Bruins captain re-signed with Boston on a one-year, $5 million deal back in March. That ensured he would be back for a 13th season with the team. In 18 games this season, he has recorded three goals and one assist along with a plus/minus of positive-three.
Chara is just the latest Boston defender to be banged up. Charlie McAvoy (concussion), Kevan Miller (broken hand), John Moore (lower body), Brandon Carlo (upper body) and Urho Vaakanainen (concussion) have all dealt with injuries this season.
The Bruins are 10-6-3 through their first 19 games, with their 23 points good enough for the top wild-card spot in the Eastern Conference at the moment.