Flyers defenseman Chris Pronger will have surgery on his left knee Tuesday and will be out for one month. "The procedure will clean out some loose particles that have given Chris some problems over the last month or so," Flyers general manager Paul Holmgren said in a statement. "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 yesterday, it was decided that the surgery is the way to go at this time. "We expect Chris will be back playing in four weeks."