The Lions moved Campbell (neck) to injured reserve Saturday.
Campbell suffered a neck injury while making a tackle in the third quarter of last Sunday's win over Minnesota and remains in the hospital. Detroit head coach Dan Campbell shared Friday that the linebacker continues to improve, but his placement on IR means he'll miss at least the team's next four games. K.J. Britt, who Detroit signed off New England's practice squad Wednesday, may be asked to immediately step into a starting role.