A day after undergoing surgery to repair a torn meniscus, the Broncos placed the running back on injured reserve, a source informed of the situation told NFL Network Insider Ian Rapoport on Friday.
Anderson's recovery time is expected to last months, Rapoport reported, although he could start jogging again in six weeks. There is a very slim chance he could return to the team if it makes an extended playoff run, Rapoport said on NFL Network's Up to the Minute Live on Friday.
The running back initially denied reports regarding the serious nature of the injury, writing "false" on Twitter, but then later deleted the posts.
Later on Thursday, Anderson tweeted out a statement thanking his family, teammates and fans for their support.
The initial diagnosis was a bone bruise in Anderson's right knee that would have cost him at least a few weeks. Worse news came with a second opinion.
The news is a brutal blow for Anderson, who was coming off the best performance of his season: 107 yards on 16 carries and a touchdown. The 6.7 yards per tote average was more than two yards better than his season average.
Rookie Devontae Booker saw his role increase heavily in Week 7, toting 17 times. He'll now take over the workhorse role. Booker displayed power between the tackles, good vision and a bowling-ball running style. Third-year pro Kapri Bibbs will play a support role with fullback Andy Janovich possibly seeing increased snaps. The Broncos promoted Juwan Thompson from the practice squad to the 53-man roster.