McManus played 166 games for the Knights and believes he was let down by the NRL club’s concussion management policy and will have his case heard at the NSW Supreme Court next month.

Fairfax Media state McManus’ suit against the club arose from the Knights allegedly urging the winger to continue playing after a head knock in a 2013 semi-final against Canterbury.

McManus claims he was allowed to return to play after being dazed and suffering a suspected facial injury in a round 20 game in 2015 against South Sydney.

He never took the field again and sat out the 2016 NRL season due to complications resulting from concussion with the 31-year-old officially retiring in August last year.

It's also reported McManus, who is employed by the Knights in a marketing role, will allege unqualified people made on-field decisions relating to him playing after head-knocks.  

Newcastle have strenuously denied mismanaging McManus' injuries.

"My health is my number one priority and I have been closely managing the injuries that prompted my retirement from professional rugby league last year," McManus said in a statement through his lawyers Slater and Gordon.

"This is not a situation I ever wanted to be in and I'm working closely with my legal team at Slater and Gordon and the club to resolve the matter and try to ensure no other player, at any other club, on any level of sport, falls through the cracks in the same way again.

"The Knights are an integral part of the Newcastle community that my family and I call home and I would ask that our privacy be respected as discussions with the club continue."