Raiders safety Derrick Gibson was placed on injured reserve Friday, five days after dislocating his left wrist. Gibson was injured early in Oakland's 38-17 victory over Buffalo. The fifth-year pro from Florida State underwent surgery Monday to place pins in his wrist. Oakland signed linebacker Isaiah Ekejiuba from the practice squad to take Gibson's roster spot. Jarrod Cooper, Stanford Routt and Chris Carr all will help fill Gibson's absence on Sunday at Tennessee. Gibson's promising career repeatedly has been derailed by injuries. He missed all of the 2004 season on injured reserve after he dislocated his shoulder in the final preseason game.