With Kerby Joseph heading to IR, a tumultuous season-long saga is over. Here is the complete analysis based on what we know as of December 20, 2025.
Let’s start with the full timeline…
Chronological timeline of Kerby Joseph left knee injury
2024 season Did not miss a game and made All-Pro.
2025 July training camp Bothered by an unspecified left knee issue the first few weeks of camp. The knee was still bothering him on August 14. He was able to return to practice on August 21.
Here is a pic of him wearing a knee sleeve in late-July (credit @DrLurker6223 for the spot).
September 14 (Week 2) Knee pops up on Friday injury report
September 22 (Week 3) Knee is on report all week
September 28 (Week 4) Injures or aggravates knee as he is blocking on an interception return. My hope at the time was for “only” a mild PCL sprain or a simple contusion.
October 5 (Week 5) Plays with left knee brace.
October 12 (Week 6) Did not wear knee brace this game. Clearly hampered by knee early in game. You can see in the video that he has discomfort with flexing his knee causing his foot to drag.
He ends up being helped off field, but then returns to finish the game. This was his last game of the season of which he played 6 games.
November 30 (Week 14) Dan Campbell provides first details of injury.
Key statements are:
“Trying to get some stability… which will help some of the pain and wear-and-tear… so it doesn’t wear out as fast.”
“I don’t think it’s necessarily going away but you do the best you can to manage it…. It’s like a lot of these guys that have deals which could be cartilage or meniscus…. There will always be a little wear-and-tear. It’s just how bad is it.”
“Bone bruise is certainly part of it… He’s got some wear.”
Kerby Joseph himself stated: “My knee’s messed up. Don’t fix it. Just keep the faith.”
December 1 Joseph starts the week with a limited practice which is his first practice since before Week 6. In this video courtesy of @colton_pouncy, you can see him trying not to put weight on that left leg.
He did not practice the rest of the week.
December 10 (Week 15) Joseph again starts the week with a limited practice and does not practice the rest of week. This was also his last practice of the season.
December 12 Dan Campbell in his press conference says there has been a “setback”.
December 20 (Week 16) Joseph placed on IR. While he is eligible to return in Week 2 of the playoffs, his season is likely over.
ANALYSIS
What is the main concern?
(I have no inside information so these thoughts are educated guesses and speculation based on what we know publicly. No definitive diagnosis has been reported or disclosed so far.)
The main concern and suspicion is Joseph has significant damage to the articular cartilage of the knee - specifically to the tibia and/or femur, with the patella also a possibility. The articular cartilage is the slick surface that coats the bones and allows joints to glide smoothly.
Here are the points of data leading to this suspicion:
The phrases “not going away”, “wear-and-tear”, and “wear out” used by Campbell are often used to describe the effects of articular cartilage damage.
Confirmed bone bruise which can be a cause or effect of articular cartilage damage due to tibia and femur impact in the joint.
Discomfort with flexing and bearing weight on left leg as seen in videos. Bearing weight on missing cartilage can cause discomfort.
Unpredictability of recovery causing the delayed placement on IR as well as inability to practice more than once in a week. The effects and recovery of articular cartilage damage are difficult to predict.
Was the knee injury during training camp the same as the one that is going on now?
It’s possible he has multiple injuries, but my suspicion is that the main problem started prior to training camp. He rested for a while early in training camp and the hope was probably that it would be stable through the season. The knee was then aggravated in Week 4 and never really got better after that.
Why was he not put on IR initially?
Medical likely felt he had a chance to return within 4-6 weeks. Cartilage effects and recovery are difficult to forecast. With a star player, carrying him on the active roster is worth it even if it only saves a single game. The Lions have had healthy inactives every game so the gameday impact was minimal.
Does the knee brace tell us anything?
Here is a pic of him wearing a knee brace (credit @j_ekks for the spot).
