The Chiefs officially announced the news Wednesday, while Adam Schefter of ESPN first reported the news on Tuesday. 

Ed Werder of ESPN noted the Chiefs couldn't determine where Charles' knee pain emanated from, while "Dr James Andrews was having similar difficulty."

Charles has played in just three games this season.

Ian Rapoport of NFL Network said the severity of the injury isn't clear but noted Charles will need another surgery on the knee after he visited with Andrews.

This comes after Chiefs coach Andy Reid said "I think it’s a positive thing" when discussing Charles' decision to check with Andrews, per Terez A. Paylor of the Kansas City Star.

According to NFL.com, Charles will miss at least eight more weeks after heading to IR. Josh Alper of Pro Football Talk said he is eligible to play in Week 17 as of now but pointed out "that doesn’t feel like a particularly likely outcome given the way things have played out with his knee already this year."

Charles amassed a mere 40 yards on 12 carries in those three games he played this season as he attempted to work his way back from last year's ACL tear. While injuries have recently sapped him of his effectiveness, he was one of the best players in the league in his prime.

The four-time Pro Bowler has five different seasons with more than 1,000 rushing yards and earned the first-team All-Pro designation two times.

The 5-2 Chiefs will have to look elsewhere in the backfield as they pursue the 6-2 Denver Broncos and 6-2 Oakland Raiders in the AFC West, and they have some capable options.

Charcandrick West tallied 634 rushing yards and four touchdown runs as Charles' primary fill-in last year, and Marc Sessler of NFL.com noted Kansas City signed Bishop Sankey for depth purposes because Spencer Ware left Sunday's game with a concussion.

Ware will also factor into the rushing attack when healthy, considering he has 511 rushing yards on the season and ran for at least 70 yards in five of his seven games.