He likely will be replaced by Jeff Linkenbach.
Reitz has been inactive for seven games this season because of knee and head injuries, though he had started eight of Indy's (11-5) past 10 games. He was kicked in the head on an extra-point during last Sunday's win over Houston.
Coach Chuck Pagano says nobody else has been ruled out. Only three other Indy players did not practice Thursday and one of those, Pro Bowl linebacker Robert Mathis, was listed as not injury-related.