Brown was placed on PUP after surgery on a torn ligament in his left hip in August. Tuesday was the last day the Redskins could activate him to the 53-man roster.
Brown was a two-time Pro Bowler with the New Orleans Saints but missed the 2009 season after hip surgery. He was then traded to Washington, where he has struggled to stay healthy but was nevertheless re-signed to a five-year, $27.5 million deal last year.
Brown re-injured his hip while running sprints before this year's training camp. He returned to practice two weeks ago but suffered another setback a few days later.