The FA's statement following Keira Walsh's knee injury spoke volumes about the crisis gripping the women's game.

In it, the FA did not specify the injury Walsh suffered against Denmark on Friday, but they did feel the need to clarify she had not damaged her anterior cruciate ligament (ACL).

That stance pointed to the ACL injury epidemic that has cast a shadow over the World Cup.

"Those three letters scare the absolute you-know-what out of me," said Lionesses defender Rachel Daly on Saturday.

The relief for Walsh, who missed England's final Group D game against China here in Adelaide today, is that she is not the latest player to fall victim to an ACL injury.

But many of the midfielder's friends, team-mates and fellow professionals have not escaped the injury that is creating havoc within the game.

England's Beth Mead and Leah Williamson have been deprived of playing at this World Cup after ACL injuries, while five of the 20 nominees for the 2022 Ballon d'Or Feminin suffered ACL damage last year.

Research suggests female players are at least three times more likely to be hit by the injury than men.

What steps are being taking to find a solution and are female athletes being let down?

"I think if it happened with a [Lionel] Messi, a [Cristiano] Ronaldo, a [Antoine] Griezmann there is probably going to be a lot more done," said Mead in the wake of her injury.

One of those trying to find answers is Dr Katrine Kryger, who is an academic in sports medicine and works at St Mary's University in Twickenham. She has conducted years of research with FIFA, national teams and WSL clubs, and says the cause of the ACL crisis is complex.

"It is multi-faceted," says Kryger. "There are internal and external factors. There are factors within the female body that makes us more exposed [to ACL injuries] and I think that is interesting, because there is only so much you can do.

"But there are things that we think we can change and that is where it is really interesting."

Those internal factors centre around the physical make-up of the female body and joint alignment, with wider hips meaning greater load is put through the knees.

There are some factors, though, that can be influenced.

A key one is the schedule, with the women's calendar exceptionally congested. Players have had an unprecedented run of a major tournament every summer since 2021, and that will continue until 2026 when they will finally get a break.

"We need to start putting the players first," warned Chelsea boss Emma Hayes last season. "It's killing the players."

Another area that can be improved is their boots. Kryger worked on research with the European Club Association and surveyed 350 female players from 16 top-tier teams.

It found that 82 per cent of players experience discomfort in their feet when they play, with the market lacking dedicated boots for women.

Big brands are responding. Nike launched the Phantom Luna before this World Cup, its first boot designed specifically for women. Puma this month announced it is conducting its own research to explore ACL injuries in women's football.

More research into how to slow the ACL epidemic in women's football is needed because the current data is not detailed or clear enough. There is a debate, for example, over the impact of biological factors like the menstrual cycle.

Chelsea are one club who do track the menstrual cycles of their players, using the FitrWoman app, and since 2018 only two of their squad have suffered ACL injuries — Maren Mjelde and Lucy Watson.

"To do good research on the menstrual cycle you probably need saliva and blood samples daily," says Kryger. "Is that ethical to do blood samples every day?"

Clubs and national associations are starting to work together to find answers, with everyone aware of the benefit of sharing data.

"We need good quality research. We need big samples," says Kryger. "I think we are getting there.

"I think clubs are concerned and I think they are willing to do things to make sure their players are safe, healthy and available."