Johnson rushed eight times for 32 yards and a touchdown while failing to haul in his lone target in Sunday's 42-21 loss to the Packers.
Johnson rushed seven times for 14 yards and was not targeted in the passing game during Sunday's 27-23 loss to Chicago.
Johnson is facing more competition in the backfield from Adrian Peterson, who signed a one-year contract with the Lions on Sunday, Michael Rothstein of ESPN.com reports.
Johnson said he wears a knee brace for peace of mind, Tim Twentyman of the Lions' official site reports.
Head coach Matt Patricia said Johnson's lack of practice reps Tuesday was planned, Michael Rothstein of ESPN reports.
Johnson (undisclosed) was spotted on the sidelines with his helmet off during Tuesday's practice, Brad Galli of WXYZ Detroit reports.
General manager Bob Quinn said he views Johnson and second-round draft pick D'Andre Swift as complements to each other, Michael Rothstein of ESPN reports.
Johnson recorded 11 carries for 53 yards and a touchdown in the team's Week 17 loss to the Packers.
Johnson ran for 42 yards on 10 carries and caught his only target for one yard during Sunday's 27-17 loss to Denver.
Johnson (knee) is listed as active Sunday at Denver.