Fifpro, the world players’ union, has accused Fifa of failing to protect players during the World Cup over its treatment of concussion and said football is in the dark ages regarding the issue. It warned of the potential for lawsuits worth hundreds of millions of dollars for those injured, following the final in which Germany’s Christoph Kramer was allowed to play on after a blow to the head, before being replaced.

Fifpro claims the problem will become a “tidal wave that will engulf” the Champions League and the domestic leagues of Europe in the new season, citing the knock suffered by Tottenham Hotspur’s Hugo Lloris when he collided with Chelsea’s Romelu Lukaku in the Premier League in November. The goalkeeper played on after protesting to the club doctor.

Kramer suffered his injury in a collision with Argentina’s Ezequiel Garay in the 19th minute of Germany’s 1-0 win. The midfielder continued until the half-hour before being taken off when he appeared unsteady on his feet.

“I can’t remember that much from the game,” Kramer said. “I don’t know anything from the first half. I thought later that I went straight off after the incident. How I got to the changing rooms I do not know. I don’t know anything else. The game, in my head, starts only in the second half.”

This was the third incident at Brazil 2014 in which players continued despite taking a knock to the head. In Uruguay’s 2-1 win over England in the group stage, Álvaro Pereira described his injury as like the “lights going out” when Raheem Sterling’s knee hit his head on 61 minutes. After arguing with the team physician, he was allowed to finish the game.

In Argentina’s semi-final win over Holland Javier Mascherano clashed heads with Georginio Wijnaldum but, again, finished the game.

Fifpro wants a protocol regarding concussion to become part of the rules and for Fifa to review the laws of the game to compensate a team if they go down to 10 men while a head injury is being assessed.

Andrew Orsatti, the Fifpro head of communications, told the Guardian: “The World Cup, being the pinnacle of football, has now become a showcase for how not to handle head injuries. Clearly this World Cup has elevated this discussion to a level that can no longer be ignored and the facts are irrefutable.”

Orsatti said Fifpro wants an “independently managed sideline concussion protocol”, pointing to the growing body of evidence that supports this and the experiences of other sports, in particular the NFL in the US.

“The vast amounts of medical evidence [and] looking at other sports such as the NFL in particular, and the hard lessons they had to learn – hard lessons that ended up in court – ended up in hundreds of millions of dollars in damages to retired players [after having] drawn a very clear link between the repeated blows to the head. Irrespective of what you think of the difference between these sports, these are contact sports.

“It’s very clear that now we have a situation where nobody can any longer ignore the medical advice. We saw with Álvaro Pereira losing consciousness, as he said: ‘The lights went out.’”

Fifpro wants concussion comprehensively checked out during a match to assess whether players should continue. “We’ve seen it on other incidents where it hasn’t been measured, a protocol is not in place to measure it properly,” said Orsatti. “Clint Dempsey, the moment he broke his nose for the United States [against Ghana]: who’s to say that is not a concussion? [Also] of course in the final with Kramer; we can talk about Mascherano in the previous round.

“It can take up to 10 to 15 minutes for a sideline concussion assessment to be carried out,” he went on and he believes that incidents at present are not being investigated for long enough to be certain whether a knock has or has not resulted in concussion.

Fifpro also believes outdated attitudes to injury are impacting on safety. “The fact that players play on through the pain barrier and are celebrated as modern-day gladiators is also ignorance and lack of education. They are to be protected. You cannot ignore the reality of where we are today.

“This is a tidal wave that will engulf the sport. This is a debate that will continue as soon as the new season begins. Around Europe and elsewhere. It’s going to spread from Fifa to Uefa, the national associations. Therefore we may as well be proactive about it.

“Football has become wanting, it’s living in the dark ages .There are clear guidelines that must now become rules. It has to be independently managed without any potential vested interest. It cannot be done without an independent medical professional that has no interest in the score or pressure from the manager because a team is down to 10 men [while a player is being assessed].”

In the NFL more than 20,000 former players are considering how best to proceed regarding their own claims over damage to their health from concussion. Orsatti stated that football may, in time, face similar legal action.

“The first recognition is the damage it causes to one’s health,” he said. “The second is the potential [for] legal consequence – that’s not an easy question to answer. But there’s no way this can be ignored any longer.

“[When] playing on with a concussion there is a second impact syndrome that can be fatal if you were to suffer another blow not long after the first, which hasn’t been diagnosed properly: that is playing with people’s lives.

“Fifa is facing a lot of pressure with regard to the manner in which they have failed to protect the player.”

Fifpro also wants football’s laws to be reviewed. “Once you’ve educated the players you have to look after the managers, so we have called for a review of the laws of the game because we know the manager cannot sustain playing at a high level with one man down for 10 minutes if a player has to be removed and be forced to undergo sideline concussion assessment.”

Fifa did not respond when contacted for comment.