The Broncos will open training camp with guard Chris Kuper and center J.D. Walton on the Physically Unable to Perform list, the Denver Post reports.
Kuper suffered an ankle injury and missed most of last season. He's expected back with the team in mid-August. Walton also has an ankle injury but his return isn't expected anytime soon after having a second surgery in mid-June. Walton could miss the entire 2013 season.