The Kansas City Chiefs could be without Justin Houston for at least part of the 2016 season following a knee operation.
Outside linebacker Houston underwent surgery last month to repair his anterior cruciate ligament, the team announced on Tuesday, revealing that the injury may sideline the 2014 NFL sacks leader for next season.
Houston missed the last five games of the 2015 regular season after hyperextending his left knee in November and visited Dr. James Andrews in February for arthroscopic surgery.
Chiefs trainer Rick Burkholder said Andrews found Houston's ACL wasn't functioning properly - though it was not torn - and made a repair. Burkholder estimated Houston's recovery time to be six to 12 months.
"When Dr. Andrews took a look inside his knee, he determined his ACL was intact,'' Burkholder said. "It just wasn't functioning. He didn't do anything at that moment, brought him out of surgery.
"We all got on the phone, discussed everything and decided to have his ACL fixed.
"Right now he's in the middle of the process of total rehabilitation for an ACL injury. It was a little bit tricky because his ACL wasn't torn but it wasn't functioning the way it should. So Dr. Andrews fixed that.''
"It's too early to tell where he's at right now. But he's on the road to recovery."
Chiefs head coach Andy Reid said on a conference call: "We're hoping, just because of his work ethic and he's been a fast healer in the past, we're hoping that's not the case, that he'll be able to play this season.
"When and where that is, it's just too early to tell."
Houston, 27, led the NFL with 22 sacks in 2014 and has 56 sacks in five seasons with the Chiefs.