Bills starting linebacker Angelo Crowell was placed on season-ending injured reserve Thursday in a surprise move that came after the player elected to have surgery on his left knee.

The Bills issued a one-sentence release announcing the move hours after coach Dick Jauron said Crowell missed practice because he had elected to have arthroscopic surgery. It's not clear whether Crowell had surgery before the Bills placed him on IR, and the team did not disclose the nature of the injury, which comes as Buffalo prepares for its regular-season opener against Seattle on Sunday.

Jauron had previously said that the surgery was related to a nagging injury that kept Crowell in and out of practice during training camp and forced him to miss two preseason games last month.

Yet Jauron said he didn't anticipate the injury was so severe Crowell would require surgery. The decision was made after Crowell consulted with team doctors Thursday, a day after he practiced with the team.

"It came pretty much out of the blue. It was certainly nothing that we saw coming," he said. "It's not as we would've planned it or would have liked it certainly, but it's the way it is, so we'll just keep working. We'll go forward and be optimistic and be confident."

The Bills' 2003 third-round draft pick, Crowell was entering his fourth season as a starter and was part of a revamped linebacker group that was rounded out by veteran free-agent addition Kawika Mitchell and Paul Posluszny, who missed all but three games of his rookie season with a broken forearm.

Backup Keith Ellison will start in Crowell's place on the strong side. Ellison, Buffalo's 2006 sixth-round draft pick, has proven to be a capable backup in his first two seasons.

Crowell becomes the second Bills linebacker to go on IR after rookie fifth-round pick Alvin Bowen required reconstructive knee surgery after being hurt in training camp last month. The Bills are down to five linebackers, including untested reserve Jon Corto, who made the team after being converted from safety this offseason.

Posluszny was held out of practice as a precaution on Thursday after he twisted his ankle a day earlier. Jauron said Posluszny's ankle was still sore, but he is expected to play.

Reserve defensive lineman Spencer Johnson practiced on a limited basis because of a sore back.

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