Howard, who also missed eight games earlier in the season, went back on the shelf after leaving Monday's loss to St. Louis in the second period.
The goalie originally sprained the medial collateral knee ligament Dec. 11 during practice.
"There's fluid back on the knee. Just hopefully it gets out of there fast," Howard said.
He was selected Jan. 1 as one of three goaltenders for the American squad at the upcoming Winter Olympics in Sochi, Russia.
Howard has compiled a 9-12-8 record with a 2.64 goals against average and .916 save percentage in 29 games this season.