The initial assessment of Christian McCaffrey’s injury was accurate.

The San Francisco 49ers running back has a PCL injury in his knee, as confirmed by an MRI on Monday. The team will place McCaffrey on injured reserve, anticipating he will be sidelined for approximately six weeks.

49ers head coach Kyle Shanahan shared this information during a press conference on Monday.

“His recovery is estimated at about six weeks, so he will be going on IR,” Shanahan stated.

Concerns arose that McCaffrey had hurt his PCL during the recent 35-10 defeat against the Buffalo Bills.

The injury likely occurred during an 18-yard gain in the second quarter, where McCaffrey was tackled by Bills safety Taylor Rapp. Shortly after, he caught a toss from quarterback Brock Purdy but fell to the ground in visible pain. McCaffrey then hobbled to the sideline and entered the team’s medical tent with 11:23 remaining in the second quarter.

McCaffrey was assessed in the medical tent and was taken to the locker room shortly thereafter.

Midway through the second quarter, the 49ers announced he was questionable to return, later confirming he would not return at the beginning of the second half.

McCaffrey has faced significant injury challenges in the 2024 season.

The standout running back began the season on injured reserve and missed the first eight games due to issues with his calf and Achilles.

In four games this year, McCaffrey recorded 202 rushing yards and 146 receiving yards.

The defending NFC champion 49ers have experienced numerous injuries throughout the 2024 season. Notables like wide receiver Brandon Aiyuk (knee) and defensive lineman Javon Hargrave (triceps) are among the 10 players currently on injured reserve. Recently, they also played without offensive tackle Trent Williams (ankle) and defensive end Nick Bosa (hip, oblique).

Backup running back Jordan Mason, who performed well in McCaffrey’s absence, is also heading to injured reserve due to an ankle injury sustained during the defeat to the Bills.

This means the 49ers’ top three running backs are now out. In addition to McCaffrey and Mason, running back Elijah Mitchell (hamstring) is already on IR.

With the current injuries, running back Isaac Guerendo will be next in line for playing time in San Francisco.