The Capitals said Knuble will have surgery. The team did not say which finger was broken.
Knuble has five goals and 10 assists for the Capitals this season. He was one of Washington's major offseason acquisitions, signing a two-year deal, $5.6 million deal on the first day of NHL free agency in July.
The Capitals are still without winger Alexander Ovechkin, who missed his sixth game Saturday against the Devils with an upper body strain suffered Nov. 1. Caps cach Bruce Boudreau said Ovechkin was "close" to returning.