Johnston (knee) was placed on injured reserve Tuesday, Dale Lolley of the Steelers' official site reports.
Johnston suffered a season-ending knee injury in Sunday's 18-10 win over the Falcons, Ian Rapoport of NFL Network reports.
Johnston (leg) left the field on a cart and is likely out for the rest of Sunday's game against the Falcons, Alan Saunders of SteelersNow.com reports.
Johnston (calf) was activated from injured reserve Saturday.
Johnston has recovered from his calf injury, Brooks Kubena of the Houston Chronicle reports.
Johnston signed a three-year deal with the Texans on Friday, Aaron Wilson of the Houston Chronicle reports.
The Eagles will not tender Johnson, instead allowing him to become an unrestricted free agent this offseason, NFL.com reports.
Johnston (concussion) is active for Sunday's game at Dallas, Dave Zangaro of NBC Sports Philadelphia reports.
Johnston (concussion) has not cleared the league's five-step concussion protocol as of Wednesday, Daniel Gallen of PennLive.com reports.
Johnston (head) has been ruled out for the remainder of Sunday's game against the Cardinals.