Barner was tended to on the field for nearly 10 minutes on Saturday left the stadium in an ambulance. Medics brought out a backboard, but Barner eventually sat up and walked with assistance very slowly to a stretcher. He was loaded in an ambulance and taken to Pullman Regional Hospital for further evaluation.
The school announced during the second half that Barner was in stable condition. He is expected to stay the night in Pullman before returning to Eugene.
Barner was hurt when he was hit by Washington State's Anthony Carpenter and fumbled. Hallston Higgins recovered the fumble and two plays later, Washington State scored to take a 14-8 lead.
Barner is Oregon's third leading rusher with 215 yards and four touchdowns.
Oregon also lost quarterback Darron Thomas with an apparent shoulder injury. Thomas ran back to the locker room in the second quarter and after coming back out to the sideline never re-entered the game.
Nate Costa replaced Thomas. Costa finished 13 of 15 for 151 yards and one touchdown. He also ran for 84 yards and another score in a 43-23 Oregon win.
Thomas said after the game that he could have returned, but was held out for precautionary reasons.
Information from The Associated Press contributed to this report.