Panthers place LB Johnson on IR with knee injury

— -- CHARLOTTE, N.C. -- The Carolina Panthers have lost another linebacker to a season-ending knee injury. The Panthers placed Landon Johnson on injured reserve Tuesday and signed linebacker Jordan Senn. Johnson hurt his medial collateral ligament in Thursday's loss to Miami in his second start at weakside linebacker after Thomas Davis was lost for the season. Johnson's injury leaves James Anderson as the likely starter Sunday at the New York Jets. Senn adds depth at linebacker but also provides a needed body on special teams. He played with Indianapolis as an undrafted rookie in 2008 and was released before the start of this season. Senn was later re-signed and played in two games before being released again. Johnson had 12 tackles in the past two games.