Penguins defenseman Olli Maatta is expected to sit out the rest of this season because of a shoulder injury.

Although the decision on that might not be finalized for a few days, a source familiar with his situation said the injury that has prevented Maatta from playing since Dec. 6 has not responded satisfactorily to rehabilitation efforts.

Maatta is expected to undergo an operation once he is officially ruled out of the rest of the season, but a decision on surgery has not been finalized yet.

Maatta, 20, had one goal and eight assists in 20 games this season.