Allar was carted off late in the fourth quarter against Northwestern after a 1-yard scramble.
Specific game designations are to be announced as the Lady Lions will play in their historic home on a "more permanent" basis.
Spell is the No. 1 running back in the class of 2027.
Starting safety Zion Tracy and offensive lineman Anthony Donkoh are listed as questionable.
Can Penn State end its two-game skid against the Wildcats?
