McManus' four-year legal battle was settled on Saturday, two days before a NSW Supreme Court hearing was meant to commence for the former Knights winger.

"The claim brought by James McManus against the Newcastle Knights, which was managed by the NRL, has been finalised with the NSW Supreme Court ordering judgment for the Knights," an NRL statement read.

"The NRL is pleased that this long-running matter has been resolved in the Knights' favour.

"The NRL was confident in its defence of the claim under the Civil Liability Act and we are pleased that the matter could be resolved without further cost and expense for all parties."

McManus was the first player to take serious legal action against the sport over concussion, after the landmark $US1 billion class action against the NFL in the USA in 2015.

The former NSW State of Origin flyer launched action in 2017 over the Knights' handlings of concussions late in his career, with his lawyers arguing he suffered several in 2015.

He played his last NRL game in round 20 of that season, before retiring the following August.

It prompted his legal team to claim he'd missed out on more than $700,000 in wages that would have come later in his career, as well as claims for other medical costs.

In an early court hearing in 2017, Justice Ian Harrison had described how McManus had planned to sue the Knights for allegedly breaching its duty of care to him by continually exposing him to the risk of concussion and failing to monitor or assess him properly.

''He also contends that he should have been warned of the risks of playing when concussed or doing so when recovering from concussion but that he was not," Justice Harrison said at the time.

McManus' statement of claim detailed a number of ongoing disabilities including cognitive impairment, impairment of memory, mood swings, headaches, anxiety, depression, lethargy and sleep disturbance.

But in a defence filed by the Knights at the time, the club had claimed the risk to McManus was "obvious" and any claim should be waived.

The most recent news means the NRL's concussion protocols will not be contested in court.

It could also have a further impact on players considering taking action against the game and its clubs over the handling of concussion cases.

Australian Associated Press