The Colts have lost cornerback Marlin Jackson for the remainder of the season with a knee injury. "He did significant damage to the knee, and I'm not exactly sure, but it's probably going to involve some surgery," Coach Tony Dungy said Thursday. "I think he might get a second opinion, but right now, he's probably going to be out for a while." Indianapolis placed Jackson on injured reserve and re-signed cornerback Keiwan Ratliff, who played four games this year.