49ers: McCaffrey’s knee injury could end his season

ORCHARD PARK, N.Y. — Christian McCaffrey exited Sunday night’s game against the Bills with a knee injury to suddenly halt the best start of his already truncated 49ers season.

It also may have ended his season.

Coach Kyle Shanahan said after the 35-10 loss that McCaffrey has a posterior cruciate injury that could cut short his third season as the 49ers’ offensive catalyst. He’s set for an MRI on Monday to determine if that right knee will sideline him the remaining five games this regular season.

“Potentially. I’m not exactly sure yet. But PCL is usually a couple of weeks,” Shanahan said.

McCaffrey, on his seventh carry of this snowy night, ran to his right and intentionally slid for a 5-yard loss at the Buffalo 34-yard line. After a 5-minute exam in the 49ers’ sideline medical tent, he jogged into the locker room, with his right sock pulled down to his ankle.

Last season’s NFL Offensive Player of the Year, McCaffrey missed the first two months of this season (eight games) because of Achilles tendinitis.

This was his fourth game back, and he racked up 58 yards on his first six carries, including season-long gains of 19 and 18 yards.

He appeared to hurt his knee by landing hard on Highmark Stadium’s synthetic turf, having been tripped up by safety Taylor Rapp to end an 18-yard run 12:15 before halftime.

Said Shanahan: “He had a great week of practice. I could feel his urgency. He came out great, looking real good. Looked like he got him by the shoestring, was about to break a house call. … I never got to talk to him. I hurt for him, and it’s tough for our team not to have him.”

McCaffrey also had two receptions for 14 yards for the upset-seeking 49ers (5-6).

The 49ers initially listed him as questionable to return before downgrading him to out at halftime.

“Always when you lose great players like that, it doesn’t help,” Shanahan said. “JP (Mason) came in and ran well. (Isaiah Guerendo) ran well, too. But losing Christian isn’t fun.”

The 49ers jumped out to a 3-0 lead on their first possession, which included a third-down conversion and later a 19-yard run by McCaffrey.

McCaffrey’s injury came just after a Bills penalty nullified an interception of a Brock Purdy pass; that 49ers drive ended in a missed field goal by Jake Moody.

The injury-laden 49ers were without linebacker Fred Warner (forearm cramps) when the Bills’ James Cook scored on a 65-yard run to open their drive that followed McCaffrey’s exit.