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.
I first met him when I was 19 years old and he coached me for 13 consecutive years. I don't know how many athletes who have had that pleasure. Al Arbour was a man that left us not only feeling like champions, but left us with a lot of great memories that we can carry on through life.
— Islanders Hall of Fame defenseman Denis Potvin on former coach Al Arbour, who passed away Friday at the age of 82