The USA international has been ruled out for at least two months as he requires surgery on the hip injury which has kept him out since the summer.
The Lions remain short in defence with skipper Paul Robinson still recovering from last season's metatarsal injury and Danny Senda (Achilles) and Pat O'Connor (cruciate) long-term absentees.
But Jackett was boosted by the return of versatile defender Tony Craig on the bench during Saturday's goalless draw with Carlisle following a back injury.
Striker Jason Price also returned as a substitute at the weekend following a short spell on the sidelines with a dead leg and should be involved again.
