Now 635 days later, Marcus Lattimore hasn’t fully recovered from the knee injury he sustained at South Carolina.

The 49ers running back isn’t on field this afternoon for the first practice of training camp after he was placed on the non-football injury list last week. Today, Jim Harbaugh said Lattimore was placed on the injured list because of two issues: his surgically reconstructed knee and a hamstring injury he sustained during the offseason program.

“The trainer, doctors evaluate and make those decisions as an organization and we do what’s best for the member of the team, the youngster,” Harbaugh said. “Because ultimately that’s in our best interest. … We believe in talking to the (medical staff) we’re doing the best thing for Marcus.”

Wide receiver Bruce Ellington and center Marcus Martin, a pair of rookie draft picks, are also on the NFI list. They both sustained ankle injuries away from the facility in the month between the end of the mandatory minicamp and the start of training camp. Rookie linebacker Aaron Lynch (hamstring), a fifth-round pick, is on the PUP list after sustaining a hamstring injury in offseason workouts. Harbaugh said all three players would join practice soon. Ellington, who was a point guard at South Carolina, will be the first to return to the field.

“It doesn’t seem to be anything real serious,” Harbaugh said of the injuries to Ellington and Martin. “Both involved rolling an ankle. Basketball-type rolling of the ankle. Not playing basketball, according to them. And you have to take a man at his word. Said they were doing football drills.”

Tight end Garrett Celek was placed on the PUP list Wednesday. Harbaugh said Celek’s back stiffened after he passed the team’s conditioning test. He will have an MRI.