Collins, a defensive tackle, suffered the injury during last week's organized team activities and is looking at a possible return late in training camp or early in the season. He is likely to start camp on the physically unable to perform list.
Collins' break is similar to the one Cowboys receiver Dez Bryant suffered last year to his fifth metatarsal. Collins had a screw inserted into the foot to stabilize the joint, plus a bone graft.
The Cowboys selected Collins in the third round (67th overall) in hopes he could bolster the interior pass rush and possibly allow Tyrone Crawford to move to defensive end with Randy Gregory suspended four games and DeMarcus Lawrence looking at a similar penalty.
Collins' production slipped last season at Nebraska in part because of a switch in the team's defensive philosophies. In 2014 he had 45 tackles, 14 tackles for loss and 4.5 sacks. He had seven tackles for loss and 2.5 sacks in 2015.
The Cowboys were already planning on being without second-round pick Jaylon Smith as he recovers from a serious knee injury, and now have to hope Collins can return to form without much offseason work, training camp or preseason games.
In 2014, Lawrence, a second-round pick, broke his foot in training camp and missed the first seven games of the season. He did not post a sack in the regular season but had two in the Cowboys' playoff run.
Collins is the Cowboys' lone unsigned draft pick. The injury, however, will not affect the negotiations.