Ron Brooks and Jalen Mills will be the players who are most impacted if McKelvin can't play Monday night against the Bears.
There is good news, however, as tight end Trey Burton (calf) was a full participant after missing the season opener against Cleveland.
Wide receiver Bryce Treggs, who was claimed off waivers from the 49ers after the final roster cutdown, was also a full participant with a knee injury. Treggs also did not play due to the injury against the Browns.
Running back Kenjon Barner did not practice Thursday, but the reason was not injury related.