Injuries continue to weaken the 49ers; McCaffrey and Mason are both going on injured reserve

The San Francisco 49ers’ disastrous season continued Monday with news that both top running backs will be out for several weeks, the latest in a series of injuries as the team’s playoff chances fade.

In a conference call with reporters on Monday, head coach Kyle Shanahan said starting defender Christian McCaffrey would be placed on the injured reserve list because of a posterior cruciate ligament injury in his right knee that occurred during the team’s 35-10 loss to the Buffalo Bills on Sunday evening.

Additionally, backup running back Jordan Mason will also go on IR and miss at least four games with an upper ankle sprain. Defensive lineman Kevin Givens suffered a torn pectoral muscle that will sideline him for the remainder of the season, Shanahan said.

Shanahan admitted Sunday that McCaffrey’s injury could spell the end of his season. On Monday, Shanahan said the injury did not require surgery but that the expected recovery time would be six weeks. The reigning NFC champions are 5-7 and in last place in the NFC West with five games remaining.

McCaffrey, last season’s NFL Offensive Player of the Year, missed the 49ers’ first eight games with Achilles tendonitis. He was beginning to return to his 2023 form and had put in several long runs on Sunday when he went down badly with his knee on the snowy turf in Buffalo. During a subsequent run, after taking a few steps he slipped onto the grass without making contact and immediately went to the sidelines to be examined in the medical tent.

Mason carried the ball 73 yards on 13 carries on Sunday before also getting injured. Rookie Isaac Guerendo, who scored a 15-yard touchdown in the third quarter, now assumes the starting role for a weakened Niners team that has struggled with injuries to many of its starters all season.

The 49ers were missing five starters against Buffalo; This season, the team lost Brandon Aiyuk, Jon Feliciano, Javon Hargrave, Talanoa Hufanga and Elijah Mitchell to the injured reserve list. They also played the entire season without star linebacker Dre Greenlaw, who tore his Achilles tendon in last year’s Super Bowl loss to the Kansas City Chiefs.

On Sunday, All-Pros Trent Williams and Nick Bosa sat out and were joined by Aaron Banks, Jordan Elliott, Demetrius Flannigan-Fowles and Deommodore Lenoir. Last week, the 49ers also had to play Brock Purdy, George Kittle, Deebo Samuel, Jauan Jennings, Ricky Pearsall and Jake Moody due to various injuries.

The 49ers were also rocked by off-the-field tragedies that befell several players. This was announced on Monday Williams and his wife lost one of their expected twins during her pregnancy, and that the other was stillborn in late November. Star cornerback Charvarius Ward in October announced that his 23-month-old daughter had died after complications from birth. Ward was on bereavement leave for weeks after her death and his first game back was Sunday.

Before the season began, Ricky Pearsall was the 49ers’ top draft pick shot in the chest near Union Square in San Francisco. He has since recovered and made his on-field debut with the team in Octoberjust 50 days after the shooting.