Bills head coach Sean McDermott said Wednesday that Rapp (neck) will not practice, Maddy Glab of the Bills' official site reports.
Rapp played 100 percent of defensive snaps during Buffalo's loss to the Rams in Week 14, in which he tallied a season-high 13 tackles (eight solo), but he appears to have picked up a neck injury in the process. The Bills are only hosting a walkthrough practice Wednesday, so Rapp's participation level, or lack thereof, Thursday will be more telling regarding his chances of suiting up Sunday against Detroit.