The effects of Sunday’s prime-time loss continue to worsen for the Panthers.Fullback Mike Tolbert was placed on the injured reserve/designated to return list on Tuesday, and the guy who took his spot on the active roster may be a sign that linebacker Thomas Davis could be out for more than just one week.Tolbert, who was at running back in the fourth quarter against the Steelers after Jonathan Stewart was injured earlier in the second half, suffered a hairline fracture in his left leg after he was tackled on a screen pass.Since this is the first time the Panthers have used the IR/designated to return list since it was implemented in 2012, here’s what it means for the Panthers and Tolbert:

• Teams can use the list on a maximum of one player per season.
• It allows teams to take an injured player off their active roster, while also giving them the option to bring that player back once healthy, instead of losing him to the season-ending injured reserve list.
• A player on the list has to sit out at least six weeks of practice, and he cannot play in a game for at least eight weeks.
• The Panthers will be in their bye week eight weeks from Tuesday, so the earliest Tolbert could return to game action is the Week 13 trip to Minnesota on Nov. 30.

The Panthers filled Tolbert’s spot on the 53-man roster by bringing back linebacker D.J. Smith, a Charlotte native who was released earlier this month. That move may be a hint that Davis, who suffered a leg injury in the fourth quarter on Sunday, will be out at least a few weeks.The extent of Stewart’s injury is unknown. But head coach Ron Rivera said Monday that Stewart had a “severely” sprained knee, so the Panthers will likely be without his services for a while as well.For lack of a better word, the Panthers running back situation is a mess right now.Rivera is again hopeful that DeAngelo Williams, who missed the last two games with a hamstring injury, can return this week. Fozzy Whittaker was labeled ‘week-to-week’ after pulling his quad against the Lions. Undrafted rookie Darrin Reaves and Lache Seastrunk, who was signed to the practice squad last week, are the only truly healthy running backs currently on the roster.