Wilson hurt his left knee when Vikings quarterback Brett Favre hit him with a low block in a preseason game Aug. 31. Favre was fined $10,000 for the hit and Wilson hasn't practiced since.
Wilson played in 12 games and started 10 for Houston in 2008. He led the secondary with 63 tackles and intercepted two passes.
Walter caught 60 passes for 899 yards and eight touchdowns for the Texans in 2008. He started all 16 games for the first time in his career.
Nick Ferguson will start for Wilson and Andre' Davis was slated to replace Walter.
Copyright 2009 by The Associated Press