Texans place Clowney on injured reserve
The surgery was the second this season for the outside linebacker. He had arthroscopic surgery on the same knee after being injured in Week 1.
He played three games since the first procedure but continued to struggle with pain and swelling in his knee before deciding to have the second surgery.
The move ends a tough rookie year for the 21-year-old who had sports hernia surgery in the offseason and a concussion in training camp before injuring his knee in his first NFL game.
Houston signed linebacker Jason Ankrah from the practice squad to take his spot on the roster.
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