Alex Okafor (biceps) out for season

All Bruce Arians could do was laugh.

During an interview on SiriusXM NFL Radio on Tuesday night, Arians announced that rookie outside linebacker Alex Okafor tore a biceps tendon during the five snaps he played Sunday in New Orleans and will miss the rest of the season.

Okafor, who was drafted in the fourth round out of Texas, was inactive for Arizona's first two games and came in to replace Sam Acho against the Saints.

"So all three of our linebackers are gone," Arians said with a chuckle, the reality of the situation possibly setting in. The Cardinals are in scramble mode to replace Okafor, Lorenzo Alexander (Lisfranc) and Acho (fibula). Arians said John Abraham and Matt Shaughnessy are both better suited to play linebacker from the defensive end position.

On Tuesday, the Cardinals signed linebacker Vic So'oto to the 53-man roster and added linebacker Bruce Taylor to the practice squad. During his interview, Arians said Arizona promoted rookie practice squad linebacker Kenny Demens to the active roster. He joins linebacker Dontay Moch, who was promoted to the active roster Monday after Arizona placed Alexander and Acho on injured reserve.

Arians also said the Cards are looking to add another inside linebacker because Alexander backed up starters Karlos Dansby and Jasper Brinkley. Rookie Kevin Minter is out with a hamstring injury and isn't expected back for a few weeks. Inside linebacker Daryl Washington can return Monday from a four-game suspension for violating the NFL's substance-abuse policy.