Scans on his wrist on Thursday night revealed the damage with Klemmer visiting a specialist in Sydney on Friday afternoon to learn the full extend of his injury. He will be sidelined for four to six weeks, ruling him out of the final two Origin games.

"We are all shattered for him," Knights CEO Phil Gardner said.

"He has been simply outstanding for us this season and he showed his courage by playing with it without knowing on Wednesday night against the Maroons.

"From the club's point of view, it's extremely disappointing but it's a tough game and unfortunately, these things happen."

Klemmer, who has been a hugely influential figure in the Knights' charge into the top four this season in his first year at the club, was a powerhouse for the Blues in Origin l, playing the opening 51 minutes straight before being replaced.

He did not go back on for a second stint after leaving the field in the second half but there was no indication after the game he had suffered a significant injury.

It was only after he linked with his Knights' teammates in camp that he raised alarm bells and was sent for scans.

His loss comes as a savage blow to the Knights' finals hopes, particularly if he is sidelined for a lengthy period of time, which is the fear.

He has been the mainstay of the Knights' pack this season, averaging 176 metres and 35 tackles a game.

His place in the squad for Friday night's clash against South Sydney will be taken by Pasami Saulo, who is expected to come off the bench.