TEMPE, Ariz. -- Cardinals running back David Johnson will seek a second opinion on the left wrist injury he suffered in Sunday's 35-23 loss to the Detroit Lions, but the early prognosis is a dislocated wrist that will require surgery, coach Bruce Arians said Monday.
The Cardinals will know the full extent of Johnson's injury by Tuesday afternoon.
If a second doctor confirms Johnson dislocated his wrist, he'll go on injured reserve with a possible return. Arians wouldn't put a timeline on Johnson's return, but Arians mentioned rookie running back T.J. Logan, who will end up missing eight to 12 weeks with the same injury.
The Cardinals are signing running back D.J. Foster off the Patriots' practice squad, a source confirmed to ESPN. Foster is a former Arizona State running back.
The news of Foster's signing was first reported by NFL Network.
"It's always a huge blow to lose a top player," Arians said. "But it's not the end of the world. We've got quality guys on our team. It's an opportunity for somebody to step up. David Johnson became David Johnson because of somebody's injury."
Arians said Monday that Johnson suffered the injury on his 24-yard catch in the third quarter on Sunday. The coach had said after Sunday's game that Johnson suffered the injury on his fumble on the only play of the next drive. Johnson went down after he was hit by three players on the reception. He writhed on the ground in pain, and according to game replays, team trainers examined Johnson's lower midsection.
Johnson came off the field and said he could play, Arians said, but later couldn't play and left the game.
The wrist injury, however, contributed to Johnson's fumbling the ball on his next carry. On the replay, Johnson can be seen rolling his left wrist after the play.
Once Arians finds out the official diagnosis of Johnson's injury, he'll address the team's depth at running back, saying he has "all the confidence" in the running backs on the roster.
"Andre [Ellington] looked very good. Kerwynn [Williams] was good," Arians said. "Our young guys, we'll see what we got and what's available."
Re-signing Chris Johnson, who was cut on Sept. 1, could be an option, Arians said.