Chris Pronger, a defenseman for the Philadelphia Flyers and two-time Olympic champion with Canada, will be sidelined for the next month following knee surgery, the Flyers said on Monday. The 37-year-old National Hockey League star, who won the Stanley Cup with Anaheim in 2007 and Olympic gold with Canada in 2002 and 2010, will undergo left knee surgery Tuesday, Flyers general manager Paul Holmgren said. "The procedure will clean out some loose particles that have given Chris some problems over the last month or so," Holmgren said. "We were hopeful that the time missed with a virus that Chris has been fighting would settle things down in his knee but after an examination, it was decided that the surgery is the way to go at this time. "We expect Chris will be back playing in four weeks." That would be a welcome Christmas gift for the Flyers, who have 13 wins in 23 games to stand third in the Eastern Conference and second in the Atlantic Division on 29 points, three adrift of NHL overall leader Pittsburgh.