The Ravens on Saturday also activated special teams standout Brendon Ayanbadejo (quadriceps) from the PUP list and released linebacker Edgar Jones.
Gaither was inactive in Baltimore's first six games because of a back injury. Visits to several specialists did not improve his condition, and the Ravens finally decided it was time to free up a spot on their 53-man roster.
Gaither started at left tackle last year, but was moved to the right side during the offseason in a switch with Michael Oher.
Reed is expected to make his season debut Sunday against the Buffalo Bills. He had been sidelined while recovering from hip surgery.
Copyright 2010 by The Associated Press