"The Indianapolis Colts have placed cornerback Marlin Jackson on injured reserve and filled his roster spot by signing free agent defensive end Josh Thomas.

The club also announced that on Thursday wide receiver Anthony Gonzalez underwent arthroscopic right knee surgery to "clean out loose particles" and safety Bob Sanders visited Dr. James Andrews to get an opinion on the left elbow injury Sanders suffered on Sunday against San Francisco.

Jackson tore the anterior cruciate ligament in his left knee during a non-contact drill on Wednesday and will require season-ending knee surgery. Jackson also suffered a season-ending knee injury during practice last year.

Gonzalez aggravated his injury during a recent practice, the Colts said. There is no timetable for his return."