Allen Park — Detroit Lions coach Dan Campbell on Friday delivered some discouraging news regarding All-Pro safety Kerby Joseph.

Joseph (knee), who has been ruled out for Sunday’s game against the Los Angeles Rams, was a limited participant at practice on Wednesday before being a non-participant the following day. Campbell said Joseph suffered a “setback.”

When asked if Joseph could be a candidate for injured reserve, Campbell said: “Could be. I mean, could be. We’re at the backend of the season now. Anything, even if it’s not technically long term, becomes long term because we don’t have many games left.”

“It’s bothers him,” Campbell said of Joseph’s knee. “That’s the best way to say it.”

Joseph hasn’t played since the Lions visited the Kansas City Chiefs on Oct. 12.

Despite both starting safeties dealing with significant injuries — Brian Branch recently had surgery to repair his Achilles — Campbell said he’s not worried about the position because, “I really do trust the guys that are going back there for us, I do, man. What you lose in a couple areas, you may gain in other areas having some of these guys back there.”

Does Campbell have any long-term concerns about the NFL’s best safety tandem?

“I can’t get to next year right now,” Campbell said. “I’m not even thinking about next year right now. My focus is, right now, L.A. and then beyond. Once we get through this one, then we’re onto the next one.”

More injury updates

▶ S Thomas Harper (brain): Harper suffered a concussion in the first quarter of Detroit’s game against the Dallas Cowboys last Thursday. Campbell entered the week unsure if Harper could clear concussion protocol prior to the Rams game, but he was optimistic Friday.

“Harper will be out there at practice today, so feel pretty good about him. We’ll see,” Campbell said. “I can’t give you definitives right now, but that’s kind of where we’re at. Look, (Erick) Hallett’s been taking reps, (Daniel Thomas) has been taking reps, (Avonte) Maddox’s been taking reps. We’ve got plenty of guys, and they’re getting valuable reps. So, we’re good.”

▶ OT Taylor Decker (shoulder): Decker missed his third consecutive practice Friday, as he continues to manage a nagging shoulder injury. He’s questionable for Sunday, as are Harper (concussion), offensive linemen Kayode Awosika (foot) and Christian Mahogany (fibula), running back Sione Vaki (thumb), wide receiver Kalif Raymond (ankle) and tight end Shane Zylstra (knee).

rsilva@detroitnews.com

@rich_silva18