PHOENIX (AP) Arizona has placed Chris Johnson on the injured reserve/designated to return list, a move that means the only way the running back will play again this season is if the Cardinals reach the Super Bowl.
A person with knowledge of the situation said Tuesday that Johnson chipped or fractured his tibia where it meets his left knee. The person spoke on condition of anonymity because the team has not revealed details of the injury.
Coach Bruce Arians said on Monday that Johnson was hurt when he took a helmet to the knee in Sunday's 19-13 victory at San Francisco. At the time, Arians called it a bruised knee but had not seen the results of an MRI.
By being on the designated to return list, Johnson can't resume practice for six weeks and can't play in a game for eight weeks.
The 30-year-old running back was in the midst of a big comeback season. He is fourth in the NFL in rushing with 812 yards.
With backup Andre Ellington also injured (turf toe), the No. 1 running back job would go to rookie David Johnson. The Cardinals said Tuesday they had elevated running back Kerwynn Williams from the practice squad. Stepfan Taylor is the other running back on the active roster.
The loss of Chris Johnson is a blow to an Arizona team that, at 9-2, has the second-best record in the NFC. The players had Tuesday off and return to practice on Wednesday, preparing for next Sunday's game at St. Louis.
Johnson signed a one-year contract at the veteran's minimum of $870,000 - a deal loaded with incentives that he won't be able to reach because of the injury.
Johnson was released by the New York Jets after one season last year. He was wounded in a shooting on an early March morning in Orlando, Florida, when someone opened fire on the van in which he was riding. A passenger in the van was killed and another injured. Johnson still has a bullet in his shoulder.
He has said he believes the shooting scared teams away from him, which was why he was still available when Arizona signed him late in training camp.
When Ellington was nursing an injury, Johnson took the starting running back job with strong early performances.
In the third game of the season, at home against San Francisco, he rushed for 110 yards on 22 carries. Later, at Detroit, he gained 103 yards on 22 attempts. He gained a season-high 122 yards (on 18 carries) in a Monday night game against Baltimore and followed that with a 109-yard game on 22 rushes at Cleveland. His production had dipped in recent games.
In Sunday's game, he carried 12 times for 17 yards before limping off with the injury.
Johnson made the Pro Bowl three times and topped 1,000 yards rushing in each of his six seasons with the Tennessee Titans. In 2009, he led the NFL in rushing with 2,006 yards.
The Cardinals, who had the worst yards-per-carry statistics in the NFL last season, drafted David Johnson in the third round out of Northern Iowa, the 86th selection overall. The rookie leads the Cardinals in touchdowns with eight - four rushing, three receiving and one on a kickoff return. He scored on a one-yard run in Sunday's victory.
Johnson leads all NFL rookies in touchdowns scored. He has rushed for 139 yards in 35 carries, an average of four yards per attempt, and caught 19 passes for 241 yards.
Williams played in the Cardinals' Week 2 win at Chicago but has spent most of the season on the practice squad. Last year, he appeared in five games for the Cardinals after being brought up from the practice squad, rushing for 246 yards in 53 carries, an average of 4.6 yards per attempt.
Arizona also signed cornerback Corey White. White played in seven games for Dallas this season, one as a starter, and was released by the Cowboys on Nov. 17. He played his first three NFL seasons with New Orleans, appearing in 41 games, 19 as a starter. To make room, the Cardinals released cornerback Robert Nelson Jr.
In another move, the Cardinals released tight end Brandon Bostick from the practice squad and replaced him with safety D.J. Swearinger.
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