The first Australian footballer to take legal action against a professional sporting club over the handling of his alleged repeated concussions says the Newcastle Knights should have forced him to retire from rugby league.

Former winger James McManus, 31, is suing the Knights for damages for "permitting or requiring him to continue to be exposed to traumatic brain injury when they knew the cumulative effect could create a permanent impairment".

In a statement of claim filed with the NSW Supreme Court, McManus said he suffered multiple head knocks and concussions during his time playing with the Knights during the last three years of his eight-year career.

McManus played 166 NRL games including three State of Origin games for NSW.

He said his ongoing disabilities included "cognitive impairment, impairment of memory, mood swings, headaches, anxiety, depression, lethargy and sleep disturbance".

"The [Knights] owed a duty to exercise reasonable care to prevent [McManus] from suffering permanent brain injury as a result of injuries sustained to the head during and in the course of [his] employment while playing the game of rugby league or participating in training sessions," the statement of claim said.

"Since at least 2001, the [Knights] knew, or ought to have known that requiring a player who has suffered successive sequential head injuries to continue playing in accordance with his employment contract ... could produce permanent brain damage."

McManus argues club failed to retire him after injuries

McManus said the club failed to conduct proper medical assessments following his concussive injuries, relied on medically unqualified personnel, such as trainers, to form opinions on brain injuries, failed to retire him on various occasions after head injuries, failed to warn him of the possibility of permanent brain damage from concussive injuries and failed to tell him to get his own medical assessment.

He lists 10 incidents between 2012 and 2015 where he suffered a concussion but was permitted or required to keep playing, either the same day or in the days and weeks and months that followed.

The Knights say McManus was presumed to have known that rugby league is dangerous. ( AAP: Grant Trouville )

Because of these incidents the Knights referred him to a neurologist for examination and assessment, which revealed McManus "was suffering from concussion, disorientation, memory impairment and balance disturbance".

Notwithstanding those symptoms, McManus claims he "was required and/or permitted to play" in a match on July 25, 2015, where "he sustained another blow to his head causing severe concussion resulting in his being transferred by ambulance to the Royal North Shore Hospital".

Knights defend 'dangerous' game of rugby league

In its defence, the Knights said the game of rugby league was a "dangerous recreational activity" and denied the club was at fault for McManus' injuries.

It said the risk of harm to McManus was "an obvious risk" and he was presumed to have been aware of that.

"With the knowledge of the risk of harm the plaintiff voluntarily consented to incurring that risk and to waive any claim in respect of loss, injury or damage," court documents said.

"[The Knights] did not owe the plaintiff a duty of care to warn [him] of the risk of harm ... [the harm was] an inherent risk of playing the game of rugby league."

McManus said he was receiving ongoing medical treatment and took prescribed medications.

He claimed that because the Knights failed to manage his concussive injuries he has been deprived of the opportunity to play rugby league both in Australia and overseas.

He further alleged he missed out on sponsorship and advertising deals, and lost earning capacity in other types of employment.