Gore suffered a fractured right hip Monday night in the Niners' 27-6 victory over the Arizona Cardinals. He was joined on IR by wide receiver/special teams contributor Dominique Zeigler, who has a torn ACL in his left knee.
The moves were two of several made by the 49ers, but none will have more impact than the loss of Gore, who is the team's leading rusher (853 yards) and pass receiver (46 catches). He was injured in the first quarter Monday.
Coach Mike Singletary had already spoken with the media before the Niners' announcement on Gore. Later, the team issued a statement from Singletary that said: "It is unfortunate that we had to place Frank on IR. He is not only a great football player but a tremendous leader. He plays with such passion and desire, two traits that will serve him well as he recovers from the injury."
The 49ers filled the roster spots of Gore and Zeigler by promoting running back DeShawn Wynn and safety Chris Maragos from the practice squad. Additionally, kicker Shane Andrus was waived from the active roster and tackle Xavier Fulton was cut from the practice squad. The moves leave the team with one open spot on the 53-man roster.
Veteran Brian Westbrook rushed for 136 yards in 23 carries in relief of Gore – both were personal highs for Westbrook since the 2008 season when he played for the Philadelphia Eagles– but Singletary said the 49ers will exercise caution going forward.
"We need to be careful because of the past history with Brian, some of the injuries and things like that," he said. "It's smart for us to be careful about how we use him, how often we use him. He's a talented guy but we want to be smart about that."
Because of injuries, Westbrook has never played a full 16-game season in his previous eight seasons. Last season, he was limited to eight games with the Eagles because of two concussions. His 23 rushing attempts Monday night was the fourth highest one-game total in his career.
Dixon has 24 carries for 72 yards this season, but the team has had concerns about his ability to pick up proper pass protections. He also plays on special teams, but Singletary said his time there would probably be reduced.
Asked how he felt about Dixon's improvement in pass protection, Singletary said, "I'm pretty comfortable. Obviously, he's not Frank, but he's gotten a lot better than when we first started. We're getting to the point where we can trust him to know exactly who he has to pick up and allow him to be able to do his job."