"It isn't one specific injury," Stoops said during his weekly news conference of Phillips, who is expected to have the surgery Tuesday. "It's bothered him for the last couple years and is not improving like they [the doctors] want it to."
The sophomore had emerged as one of the best players on the Sooners' defense in the first four games but had missed OU's last two games due to the back injury. Phillips was becoming the anchor of OU's defense and had seven tackles, two sacks and 1.5 tackles for loss in four starts before the injury sidelined him.
Wade has six tackles, including one sack, in five games and Peterson has three tackles in four games. Junior Chuka Ndulue could provide help at defensive tackle, and junior college transfer Quincy Russell could also factor along the interior.
"They've played hard but they need to play better," Stoops said of Wade and the rest of the defensive tackles. "Hopefully they'll keep improving as we go."
The loss of Phillips is another blow to a defense that lost linebacker Corey Nelson for the season last week. Nelson, a senior, suffered a pectoral injury against TCU. He is also expected to have surgery Tuesday.
There was some good news for OU: All-Big 12 cornerback Aaron Colvin, who left the Sooners' 36-20 loss to Texas on Saturday with an injury, is expected to play against Kansas this weekend.