San Francisco 49ers running back Marcus Lattimore is planning on retiring from the NFL due to knee issues, a league source confirmed to ESPN.
Lattimore was not at the 49ers' 13-10 loss to the St. Louis Rams on Sunday at Levi's Stadium and, per the reports, is contemplating his future.
Lattimore, who began practicing Wednesday, sat out practice on Friday. He blew out every ligament in his right knee on Oct. 27, 2012 at South Carolina and the 49ers made him a fourth-round draft pick six months later.
Other outlets say an official decision hasn't been made as of yet. Lattimore spent the entire 2013 season on the non-football injury list and remains on that list this season. However, he did begin practicing last week with the hope that he would be able to play later this season. The 5-foot-11, 220-pound back suffered serious knee injuries in 2011 (tore the ACL and MCL in his left knee) and 2012 (right knee) during his time at the University of South Carolina.