According to the report, Rua ruptured the ACL in his left knee, which is the same injury that forced a surgery after a UFC 76 loss to Forrest Griffin.Here’s the snip:

“Scheduled to make his return to the Octagon this June against Chuck Liddell at UFC 85 in London, light heavyweight star Mauricio “Shogun” Rua has instead been forced to withdraw from the bout due to a ruptured ACL in his left knee, the same injury he had surgery on to repair last October after his UFC 76 fight with Forrest Griffin. Surgery on the injured knee will be scheduled shortly, and there is no word on when Rua will be cleared to return to the Octagon.”

“Liddell’s opponent for UFC 85, which will be held at London’s O2 Arena on June 7th, will be announced shortly. As for Rua, he promises to be back and better than ever as soon as possible. “

Mauricio ‘Shogun’ Rua (16-3) was looking forward to redeeming himself inside the Octagon after a poor performance against Griffin. Prior to his loss to Forrest Griffin, he was considered by many to be the number one ranked fighter in 205-pound category.

source: UFC.com