San Francisco 49ers reserve tackle Garry Gilliam remains in the concussion protocol, general manager John Lynch and head coach Kyle Shanahan confirmed on Saturday. He sustained the concussion during the team's exhibition opener against the Dallas Cowboys on August 9 and remains on the roster after the cut-down to 53 players.

"Any time you're dealing with the head and concussions, you don't know (when the player will return)," Shanahan told reporters via a conference call on Saturday afternoon. "It could be anywhere from a day to a year. There's no way of knowing. It is a concern when you haven't had your third tackle play since the first preseason game, but it's also the reality of what that injury is."

With no timetable for Gilliam's return, the 49ers traded a seventh-round draft pick in 2019 for Cleveland Browns tackle Shon Coleman on Friday.

"It is important to have another option because you never know when that's going to happen," Shanahan continued. "That's why we felt very fortunate that John and his guys were able to find this guy and target him. We feel good getting him here for what we gave up. We thought it was pretty important."

Coleman, a third-round draft pick by Cleveland in 2016, started all 16 games at right tackle for Cleveland last season and appeared in 23 games since entering the league.

"Shon Coleman is just a guy we had just been doing a lot of work on," Lynch added. "The more work we did, the more appreciation we had for him. Most teams carry nine offensive linemen. That's the number we're at.

"Sure, Garry's condition and being in the protocol may have contributed to [the trade], but he was a guy we were excited about independent of that, as well."