The Kansas City Chiefs could be without pass-rushing linebacker Justin Houston when they begin training camp -- and perhaps when they begin the regular season.

Houston had ACL surgery in February and is expected to be sidelined 6-12 months, according to multiple reports.

#KCChiefs announce star pass-rusher Justin Houston had his knee scoped to "fix" his ACL on Feb. 15. Recovery ranges from 6-12 months. Yikes

— Ian Rapoport (@RapSheet) March 22, 2016

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Justin Houston had ACL surgery in February and rehab is expected to be six to 12 months. Trainer Rick Burkholder...

— Adam Teicher (@adamteicher) March 22, 2016

Justin Houston had his ACL "fixed" in Feb. It wasn't torn, but it wasn't functioning the way it should. He's on the road to recovery.

— BJ Kissel (@ChiefsReporter) March 22, 2016

"It's too early to be able to tell," #Chiefs coach Andy Reid on whether Justin Houston will be ready when the season begins.

— BJ Kissel (@ChiefsReporter) March 22, 2016

Houston, 27, had 7.5 sacks and two interceptions in 2015 --€“ one season after leading the league with 22 sacks. He has been named to the past four Pro Bowls and was a First Team All Pro in 2014.

However, he missed the final five regular-season games in 2015 because of a knee injury before returning for the Chiefs' two playoff games.

Earlier this month, the Chiefs re-upped with fellow pass rusher Tamba Hali, who had 6.5 sacks last season and who has 86 sacks in his 10-season NFL career.