Terrion Arnold’s shoulder problems have lingered all year, and the Detroit Lions finally reached the point where shutting him down was the only realistic option.

The second-year corner has officially been placed on injured reserve, ending his season with five games still left to play. According to NFL Network, Arnold is expected to undergo shoulder surgery sometime this week.

Earlier in the season, Arnold missed two games with what was initially an unclear shoulder injury. A favorable second opinion helped him return quickly, but head coach Dan Campbell said the problem never truly healed — and it was clearly affecting him during Detroit’s Thanksgiving loss to the Packers. He also missed time recently due to a concussion before returning last week.

After logging over 1,000 snaps as a rookie — leading the league in man-coverage reps — Arnold simply couldn’t stay on the field in 2025. He exited early in five of the eight games he played and missed four others entirely.

Injuries first popped up for him coming out of training camp, and from there, the setbacks kept piling up.

“It’s frustrating — for him especially,” Campbell said. “It just feels like one of those years. He had a great start to camp, then injuries hit, and it kept snowballing. It’s just a tough year for him.”

With Arnold out, Detroit will rely heavily on Amik Robertson and Rock Ya-Sin to hold down the outside corner spots. D.J. Reed has two games under his belt after returning from a long hamstring recovery, giving the Lions another option.

Expect Robertson and Ya-Sin to rotate on Thursday against the Cowboys, while Robertson’s ability to slide inside adds some flexibility. It’s a tough draw against a Dallas offense rolling behind CeeDee Lamb and George Pickens as Dak Prescott continues a hot streak.

Pickens has racked up 378 yards and two touchdowns in the past three games, while Lamb has added 253 yards and two scores. Prescott has surpassed 300 passing yards in back-to-back games. For Detroit to survive with its man-heavy scheme, the pass rush needs to regain its early-season effectiveness.

Safety Kerby Joseph practiced once this week but was absent again Tuesday, leaving his return timeline uncertain. Thomas Harper and Brian Branch are expected to handle most of the safety duties for now.

Defensive coordinator Kelvin Sheppard didn’t hold back when discussing the defense’s recent struggles.

“We haven’t pressured the quarterback enough to play our style,” Sheppard said. “The players know that. And it starts with me. Yeah, guys need to win one-on-ones — that’s obvious — but I also have to help put them in the best situations to do that.

“That’s coaching, communication, and adjustments. We haven’t disrupted quarterbacks the way we did earlier in the year. So we’ll be changing some things up — personnel-wise and scheme-wise.”