PITTSBURGH (AP) -- Pittsburgh Steelers defensive end Aaron Smith will miss the rest of the season with a torn rotator cuff in his right shoulder, an injury that significantly weakens what was the NFL's best defense the last two seasons.
The Steelers placed Smith on the injured reserve list Wednesday, which means he cannot play again this season. He is scheduled to have surgery later this week.
To replace Smith on their 53-man roster, the Steelers re-signed Ra'Shon "Sunny" Harris, a sixth-round draft pick that they cut in September. Harris had been on the Carolina Panthers' practice squad.
Steelers coach Mike Tomlin plans to use several players to replace Smith, one of the NFL's top defenders against the run. Tomlin said first-round draft pick Ziggy Hood isn't ready to step into the job full time, and that Travis Kirschke and Nick Eason also will play.
Smith last missed playing time during the 2007 season, when a torn biceps kept him out of the Steelers' final three regular season games and a playoff loss to Jacksonville. The Steelers allowed 629 yards rushing in those four games without Smith.
The Steelers are fourth in the league in total defense and second against the run.