The Redskins have placed running back Clinton Portis on injured reserve, the team announced on Tuesday.
Portis is still recovering from a concussion he suffered on Nov. 8 at Atlanta.
Portis visited with a concussion specialist in Pittsburgh this week. It was thought he would get final clearance to resume playing, but instead it was decided he should not play again this season.
"We felt at this juncture in the season, it was best to place Clinton on injured reserve," Redskins executive vice president of football operations Vinny Cerrato said. "After consulting with our medical staff and other specialists, Clinton's prognosis is good and we expect him to make a full recovery and return to the Redskins."
In an interview on ESPN 980 on Tuesday, Portis said he continues to be diagnosed with vision problems as a result of the concussion.
"I was really hoping I could get back on the field," he said. "I think we had a key stretch with the Saints, Dallas and New York all being this month, and then we had Oakland and San Diego as well.
"I came up here hoping to be cleared to resume normal activity, but the doctor said he wasn't going to do it. He didn't like what he saw [in the exams]...the doctor feared that if I took another hit like that, then it could get worse."
Portis was optimistic that he would "get well," but admitted to uncertainty about his future in the NFL and with the Redskins.
"I think I have to go and really put the time into rehabbing and continuing to do what the doctors say," he said. "But at the same time, to have the opportunity to play for eight years and compete.
"I look back today, I feel like I've had a great career...No one wants to finish with an injury, but at the same time I enjoyed it and I'd love to get back on the field."
Portis played in eight games this season and rushed for 494 yards on 124 carries and one touchdown. He also caught nine passes for 57 yards and a touchdown.
For his career, Portis has compiled 9,696 rushing yards on 2,176 carries and 73 touchdowns. He has caught 81 passes for 290 yards and five touchdowns.
-- ROBINSON ADDED TO PRACTICE SQUAD
The Redskins signed wide receiver James Robinson to their practice squad on Tuesday.
To make room for Robinson on the practice squad, the team released wide receiver Keith Eloi.
Robinson, 6-3 and 200 pounds, has spent parts of the 2009 season on both the Cleveland Browns' and Miami Dolphins' practice squads. He signed as a member of the Browns' practice squad on Nov. 18, but was released on Dec. 1.
Robinson originally entered the NFL as a free agent with the Miami Dolphins on Aug. 10, but was later released on Sept. 5. He re-signed with the Dolphins' practice squad on Sept. 7, but was released on Nov. 3.
Robinson played college football at Butler (Kan.) Community College.
Eloi was signed to the Redskins' practice squad on Dec. 2.