LOS ANGELES — Gavin Stone, the only Los Angeles Dodgers starter to take every turn this season, was placed on the injured list with shoulder inflammation Friday, adding more uncertainty to a star-studded rotation that has been in flux all year.

Stone hasn’t been ruled out for the rest of this season, but the calendar makes a potential return extremely challenging. Stone will shut down his throwing for “10-ish” days, Dodgers president of baseball operations Andrew Friedman said, after which he will hope for the best.

“I’m optimistic he is going to do everything he possibly can,” Friedman said. “There’s just so much unknown around it that we’re going to do all we can to dominate each day, and hopefully when he starts throwing, he can ramp up from there. It’s just hard to speculate right now.”

With 25 days remaining until the start of the postseason, the Dodgers have four key starting pitchers waiting to come off the IL: Stone, Tyler Glasnow, Yoshinobu Yamamoto and Clayton Kershaw.

Yamamoto will be activated to start Tuesday’s game, but he has been out since the middle of June with a strained rotator cuff and isn’t expected to be stretched out to more than four innings. Glasnow, out since Aug. 11 with elbow tendinitis, will throw a bullpen session Saturday that will go a long way toward determining his readiness for October. Kershaw, meanwhile, exited his Aug. 30 start against the Arizona Diamondbacks with a bone spur in his left big toe. His timetable is uncertain.

Jack Flaherty seems to be the only lock to start postseason games for the Dodgers at this point, though Walker Buehler has also shown promising signs of late. The Dodgers called up right-hander Landon Knack and left-hander Justin Wrobleski for temporary relief, optioning right-hander Michael Peterson to create the extra spot on the active roster. Knack and Wrobleski are two of 12 pitchers who have made traditional starts for the Dodgers this season (not counting openers).

The aforementioned injuries don’t even account for promising young starters who have undergone major arm surgeries over the past 14 months, a list that includes Tony Gonsolin, River Ryan, Emmet Sheehan and Dustin May.

“It’s been a really challenging year on that front and something that we’re going to need to spend a lot of time on this winter to really dig in on — from when we onboard a pitcher, when we draft or trade for him, through the development path, at the major league level,” Friedman said.

“Obviously it’s a problem in the industry. And the injuries that are happening to us, we feel. The injuries that are happening to other teams, we don’t feel as much. They don’t quite hit home the same way. And so, we’re going to do everything we can to put ourselves in the best position going forward. But obviously all of our focus right now is to do what we can to finish the regular season strong, be in the best position to go out and win hopefully 11 games in October.”

Stone, 25, has made 25 starts in his first full season in the major leagues, going 11-5 with a 3.53 ERA in 140⅓ innings. Friedman said Stone felt “discomfort” in his right shoulder coming out of his Saturday start against the D-backs, prompting imaging and a subsequent visit with team doctors who recommended rest. An MRI, based on Friedman’s comments, was inconclusive.

“It’s really more symptom-based,” Friedman said. “It wasn’t something that it was like, ‘Oh, we need to have surgery.’ It was, ‘Hey, let’s let everything calm down, let’s pick back up a ball and see where we’re at.’ And to the extent that he comes back and feels good and doesn’t have symptoms, I think we’re in a good spot. If he does pick up the ball and has problems, then we’re in a tough spot. We’ll have a much better feel for that once we get back to the throwing phase of where we are.”