SANTA CLARA, Calif. (AP) — Dee Ford will miss at least another week of training camp with knee tendinitis.

The San Francisco defensive end received a platelet-rich plasma injection this week to accelerate the healing process in his knee. The 49ers officially list Ford as day to day, but will be cautious and not rush him back with more than a month before the regular season starts.

"He could have toughed it out and gone through (practice) like a lot of guys try to do because they're trying to make the team and get better," head coach Kyle Shanahan said of Ford on Sunday. "We feel good about where Ford's at. We wanted to make sure we took care of him so he could be fresh going into the season."

Ford injured his knee Tuesday, July 30 during practice and left halfway through it. "He's fine," defensive coordinator Robert Saleh said at the time. "Just aches and pains of training camp."

Ford attempted to return to practice on Friday — he participated during individual drills with his position group. But, he still felt pain in his knee, so he left practice and did not participate in 11-on-11 team drills. After practice, the 49ers discovered he had knee tendinitis.

"(Ford) says it happens about every camp and then usually goes away," Shanahan said. "He went out there and it was bothering him, so we just pulled him."

Ford participated in every practice of OTAs and minicamp, as well as the first three days of training camp. But, since he injured his knee, he has missed team drills in five straight practices, and likely will miss the 49ers' preseason opener against the Dallas Cowboys Saturday, Aug. 17.

"It doesn't seem like a cause for concern," Shanahan said. "You can tell usually when you talk to a player and he says he's used to (the injury) and it's something that happens to him every camp."

The 49ers traded their second-round pick in 2020 to the Kansas City Chiefs for Ford on March 12, and immediately gave him a five-year, $87.5 million contract extension through 2023.

Ford, 28, was a first-round pick in 2014. The Chiefs took him with pick No. 23. In 2018, his final season under contract with Kansas City, Ford recorded 13 sacks and earned his first trip to the Pro Bowl.

Despite his stellar performance last season, the Chiefs chose not to offer Ford a contract extension. Instead, they gave him the franchise tag on March 4, then traded him to the 49ers eight days later.

Ford has not always been a consistent producer since entering the NFL. In five seasons, he has recorded double-digit sacks only twice. And he generally struggles to defend the run. Last season, he was one reason the Chiefs defense gave up 5.0 yards per carry - second highest in the NFL.

Ford also has had injury issues. In 2011, his junior season at Auburn, he injured his back and missed 10 of 13 games. Then, in 2017 with the Chiefs, he reinjured his back. This time, the injury required surgery and he missed 10 of 16 games.

The 49ers were aware of Ford's back issues when they traded for him this offseason. Shanahan would not say if the 49ers also were aware of Ford's history of knee tendinitis.

"I mean, you hear about wear and tear with guys," Shanahan explained. "You get every medical report that they've ever had from their trainers. Usually, you've got to do something like what we did (with Ford's knee) once in the year. We thought it would be better to do it sooner than later."