The Detroit Lions placed running back Jahvid Best on the physically unable to perform list Friday, ending his season, according to the team's website.
Best had not been cleared to play by doctors this season because of past concussion issues. The team decided to shut him down after he recently took a battery of post-concussion tests.
The Lions hoped Best could play this season after he sat out a significant portion of last year with multiple concussions. Considering he still cannot play, his career may be at risk.
"There has been subsequent evaluation and consultation regarding Jahvid since our last update (Oct. 15)," Lions general manager Martin Mayhew said on DetroitLions.com. "As has been the case throughout, we have deferred to the medical experts and support their current recommendation that Jahvid not return to the field this season. Jahvid's approach to this situation and his adherence to the process and protocol have been exemplary.
"No one has worked harder or shown more dedication than Jahvid has over the past year. As disappointing as this decision is for us and Jahvid we do believe it is in his long-term best interest."
Best played in six games last year and rushed for 390 yards with two touchdowns. He also caught 27 passes for 287 yards with a TD.