Concerns are growing about the long-term outlook for Detroit Lions safety Kerby Joseph after a sobering assessment from a well-known NFL medical expert.

Dr. David Chao, who spent 17 seasons as an NFL head team physician and now runs Sports Injury Central, shared his thoughts on Joseph’s knee situation while speaking with the Detroit Free Press during Super Bowl radio row. Among several Lions players discussed, Joseph’s case stood out as particularly troubling.

Chao was informed that Joseph, a former third-round draft selection, has been exploring non-surgical options to address his knee issue, including potential stem cell therapy. While Chao emphasized that he has not personally reviewed Joseph’s medical records, the mere discussion of such treatments raised red flags in his view.

“This is a risky situation,” Chao said, while stressing that he is rooting for the 25-year-old. He explained that damage to articular cartilage presents one of the biggest challenges in sports medicine. According to Chao, cartilage does not regenerate easily due to limited blood supply, making it far more difficult to repair than other tissues. He compared it to the tread on a tire—once it’s worn down, replacing it is not straightforward.

To illustrate the concern, Chao referenced veteran pass rusher Jadeveon Clowney, who underwent microfracture surgery early in his career to address cartilage damage. Chao noted at the time that the procedure could dramatically alter Clowney’s career trajectory. Although Clowney has exceeded many expectations in terms of longevity and production, teams have remained hesitant to offer him long-term contracts because of lingering concerns about his knee.

In Joseph’s case, Chao suggested that even considering stem cell therapy could indicate a more serious situation than one that would typically be treated with microfracture surgery alone.

“I don’t know how severe Kerby Joseph’s knee condition is,” Chao said, “but when stem cells enter the conversation, that usually means you’re dealing with something beyond standard options.” While he acknowledged that stem cell treatments can sometimes provide benefits, he cautioned that the outcomes are unpredictable and far from guaranteed.

Chao expressed concern not only for Joseph but also for the Lions organization. He suggested that if Detroit is able to get a productive year or two out of Joseph moving forward, that might already be considered a success under the circumstances.

“Expecting him to fully play out this contract and then earn another one would be a long shot,” Chao said, adding that he hopes his assessment proves overly pessimistic.

As of now, there has been no official update on Joseph’s recovery timeline or rehabilitation progress. Sources contacted by Detroit Lions On SI did not provide additional details regarding his current status.