Seidenberg injured his ACL and MCL in the third period Friday against the Ottawa Senators in an awkward fall.
Bruins general manager Peter Chiarelli said the team has recalled defenseman Zach Trotman from Providence of the American Hockey League on an emergency basis and assigned goaltender Niklas Svedberg to Providence. Trotman will join the team in Ottawa on Saturday and is eligible to play.
The Bruins said Seidenberg is expected to need 6-8 months to recover.
Seidenberg, 32, had one goal and nine assists in 34 games this season. He is second on the Bruins in time on ice at 21:50 per game, behind the 25:02 of Zdeno Chara.