Anderson, who signed a four-year, $27 million contact prior to the season, suffered the injury -- and had difficulty putting any weight on it -- in the second half last Sunday during the 45-3 blowout at San Francisco.
"It looks like he needs surgery and he is going to be out. I don't know how long," Bills coach Chan Gailey said. "He will be back. It is not like he is going to miss the rest of the season. They just said indefinite and they will no more when they go in."
According to general manager Buddy Nix, Anderson will visit Dr. James Andrews to determine the severity of the injury.
That leaves 10-year veteran Chris Kelsay to take over the starting duties at right defensive end. Kelsay traditionally plays the left side. Kyle Moore will also see action and former All-Pro Mario Williams will remain at his left end spot.
"(Anderson) has been a very good addition to our football team. You hate to lose people that have his kind of energy and have been playing the way that he has been playing," Gailey said. "It hurts your depth, it hurts your pass rush, and it hurts every little thing there. Next guy in line has to step up. We got three defensive ends right now and those guys are going to have to make it happen."
Copyright 2012 by The Associated Press