Coach Dan Bylsma says Kobasew was hurt in the first period of Monday's 3-1 win over the Carolina Hurricanes. Kobasew, who signed with Pittsburgh as a free agent in the off-season, has two goals in 12 games for the Penguins.
Kobasew's injury came one game after the Penguins lost defenceman Rob Scuderi with an ankle injury that will require surgery.
The Penguins are already playing without forward James Neal (upper body), forward Beau Bennett (undisclosed injury) and goaltender Tomas Vokoun. Vokoun is out until at least January while he recovers from a blood clot.
Pittsburgh forward Brandon Sutter did not practice on Tuesday. His status for Wednesday's game against Boston is unclear.
He's a winner. We want winners here, and he's a proven winner. He's won two Stanley Cups. He's 22 years old and been a big part of it. He's got all the right tools. He's got size (6-foot-1, 204 pounds) and strength. He's exactly what we were looking for. He's going to be a big piece of our team for many, many years to come.
— Blue Jackets GM Jarmo Kekalainen on Brandon Saad, who he acquired in a trade with the Blackhawks on Tuesday