The 24-year-old was initially knocked out in the first quarter, then returned for one second-quarter carry of 2 yards. He then went back to the sideline and remained there for the rest of Pittsburgh's scoring drive (which culminated in a field goal), with no helmet and wearing a jacket.
He returned to the sideline in the second half but never took the field, finishing with 20 yards on six carries.
DeAngelo Williamsrushed for 34 yards on 14 carries and a touchdown in relief of Bell.
Coming into the game, Bell had rushed for a combined 337 rushing yards in the 2017 AFC playoffs, an NFL record for a running back's first two career playoff games.