Early reports from Brown himself indicate that his knee injury is most likely a sprained MCL, according to Larry Holder.
#Saints T Charles Brown said in the locker room he probably sprained the MCL in his knee. Left locker room on crutches.— Larry Holder (@LarryHolder) November 19, 2012
Brown left the game before half time and was replaced by undrafted rookie Bryce Harris.
This isn't good news for Drew Brees and the Saints, who lack depth at the tackle position.