NFL rules allow for one player to be eligible to return to the active roster eight weeks after his injured reserve designation, so one of the two could return in early December while the other will miss the rest of the season.
Johnson and Branch are both dealing with groin injuries suffered during Sunday's 17-13 loss to the Los Angeles Rams.
Both players are having sports hernia surgery according to reports. Andre Ellington and Stepfan Taylor are the other two backs on the Cards roster and Ellington has had his share of injuries in his career. The team, on Tuesday, re-signed running back Kerwynn Williams, who was released before the season began.