As though the quantity of their injuries wasn't enough cause for concern, the San Francisco 49ers are even having trouble finding out the severity of their many ailments as they begin their week at the Greenbrier Resort in West Virginia.

Niners coach Kyle Shanahan had only limited injury updates in his usual Monday media session because of something else entirely out of the team's control.

"We had an MRI truck scheduled up here, and that truck broke last night," Shanahan said. "The local hospital is helping us out with MRIs, so that's why we're behind on everything."

The 49ers are still awaiting official word on the knee injury to defensive lineman Solomon Thomas, who is feared to have torn an ACL, though Shanahan said Sunday there was at least a little hope he had not.

The team confirmed later Monday that defensive lineman Nick Bosa suffered a torn left ACL on Sunday and will miss the rest of the season.

Shanahan did have some updates on some of the many other injuries the Niners suffered in Sunday's 31-13 win against the New York Jets.

Quarterback Jimmy Garoppolo, who has a high right ankle sprain, is still considered day-to-day, according to Shanahan. While that injury usually requires at least a month to recover, Shanahan said the "severity is not real bad," which means Garoppolo has a chance to play Sunday -- rather than backup Nick Mullens -- against the New York Giants.

"If he's good to go and the doctors say he's healthy and he can go out there and protect himself, and if Jimmy feels confident in doing it and it gives us the best chance to win, if that's the case, then Jimmy will be out there," Shanahan said. "If Jimmy is not safe and can't protect himself, then we'll go with Nick."

A source told ESPN's Adam Schefter that running back Tevin Coleman is expected to miss multiple weeks with a sprained knee. Running back Raheem Mostert, who suffered an MCL sprain, will "most likely" miss this week's game. With Coleman and Mostert both expected to be out, Jerick McKinnon and Jeff Wilson Jr. will handle the primary running back duties against the Giants.

The 49ers are also monitoring an ankle injury to defensive tackle D.J. Jones and keeping tabs on injuries to players who were already dealing with ailments before Sunday's game. Tight end George Kittle (knee) will be evaluated as the week goes on while cornerback Jason Verrett (hamstring) is expected to return to practice Wednesday.

Of more concern is defensive end Dee Ford, who was a pregame inactive because of what was then called a neck injury. Shanahan explained Monday that further testing to Ford revealed more of a back issue.

"It's more of a back injury than neck spasms, so anytime it's the back, that is an issue," Shanahan said. "So, we're still working into that, but at least we can clarify what it is."

With Ford's status uncertain and Bosa out for the rest of the season, the 49ers agreed to terms with veteran defensive end Ziggy Ansah on a one-year deal. Ansah visited with the team twice previously but did not come to an agreement.

In San Francisco, Ansah reunites with defensive line coach Kris Kocurek, who worked with him in Detroit. Ansah must go through the COVID-19 testing, but assuming he is cleared, he will be able to practice this week and could play against the Giants.

"I've played against Ziggy a ton," Shanahan said. "He's a hell of a player, can rush the passer and play the run well. Hopefully, we can get him in here soon, get him caught up."

Ansah joins a thin group of healthy defensive ends that also includes Arik Armstead and Kerry Hyder Jr. Shanahan said the Niners could add more at the position as the week goes on and other injury issues get more clarity.

As for returning to the playing surface at MetLife Stadium that the 49ers found problematic on Sunday, Shanahan said general manager John Lynch reached out to NFL head of football operations Troy Vincent to try to get some reassurances for their team.

As the league and NFL Players Association reviews the 49ers' complaints about the "sticky" MetLife Stadium turf, sources told ESPN's Chris Morytensen that the field has undergone 20 inspections since being installed in June. A final inspection on Sept. 12 certified it as compliant with mandated policies for artificial turf and the Jets certified again Thursday, the source said.

Shanahan also acknowledged that the Niners will take the playing surface into consideration before asking players already dealing with injuries such as Kittle to come back and play against the Giants.

"We'll think about that with everything, especially with George coming back and especially the issue with the field," Shanahan said. "Nothing has changed with me with the field yet. I haven't been able to talk to anyone. I know John talked to Troy earlier today and they're definitely looking into it. So, hopefully at some time we get some answers back that can make our players feel a little bit more at ease playing there next week."

In the meantime, the 49ers will hold out hope that nothing else goes wrong this week on their two-game, 10-day East Coast swing. Perhaps it should have been an ominous sign that the trip to the New York area got off to a rough start on Friday.

According to Shanahan, the plane the team was supposed to take out of San Jose airport was crashed into by people working, leaving it dented and deemed unsafe to fly. So, the Niners had to go to San Francisco airport to get on a new plane. After a six-hour delay, they were finally on their way.

"It just got us in real late," Shanahan said. "We didn't get in until about 2:30 [a.m. Saturday], and got to the hotel around 4 [a.m.] and we were supposed to get there at 9 [p.m. Friday]. Luckily, we came on Friday. It would've been a big issue if we came on Saturday."