A 'quick fix' to the ACL epidemic in women's football is unlikely anytime soon

Every time a women's football star joins the dreaded anterior crucial ligament (ACL) club, attention returns to why they are two to three times more likely to tear their ACL than their male counterparts.

Sam Kerr succumbing to the injury for a second time in her career this month was no exception, as many wondered how the 30-year-old had added her name to the ever-growing ACL list in the women's game.

But even with all the funding being pumped into research to prevent and treat the injury in female athletes, a "quick fix" is unlikely to be found as to why women are more likely to succumb to the injury.

The answer emerging, after more than 20 years of research that has not succeeded in reducing the prevalence of ACL injuries in female athletes, looks at the role gender plays instead.

Medibank's medical director for research, policy and innovation, Dr Jessica Choong admits "it would be great if it was just one simple" answer.

But as more funding is dedicated to researching why women are two to eight times more likely to suffer an ACL tear than their male counterparts when football is left out of the equation, it is becoming more apparent that will not be the case.

"There are multiple factors that contribute. So there are things that we can change and there are things that we can't change. We can't change our anatomy, our body shape, and what we also can't change are female sex hormones without medical intervention and even then, we're not really clear on what role they play in terms of injury rates," Dr Choong told Optus Sport.

"But the things that we can change is how we use our bodies, so the training and the development of our muscles and the way that we learn to move safely in sport. Building that core strength, ensuring that our hips and our supporting leg muscles are strong, making sure that we're learning how to land correctly from a jump, how to pivot and turn quickly and all those sorts of risky manoeuvres for an ACL injury.

"And then there are other things like the equipment and the facilities available to women. The turf that women play on is often not at the same professional level as what's available to the men. So there are just so many different possible contributing factors. But I think the good thing about that is that there are also lots of things you can chip away at.

"Injury prevention programmes are probably one of the most important things that we're seeing and we've noticed that they're reducing the rates of ACL injuries, sometimes by half. So that's actually a massive impact and something that's achievable."

The answer as to how to fix it is where the research differs and becomes complicated.

Money was pumped into researching ACL injuries in the 1990s as a result of an NCAA study. Ever since the biological traits of female bodies have been the leading answer behind why the prevalence is higher in women.

The female pelvis is wider, which puts more stress on the soft tissue of the knee. Women typically have less muscle mass around their knees than men which can cause instability, as they tend to be 'quad dominant' and lower hamstring strength can impact knee control. Women house a narrower groove that the ACL travels through in the femur, have a smaller ACL and are more likely to land flat-footed following a jump with their knees rolling inwards.

Another answer leading the discussion is the effect female hormones play.

The results are still not conclusive, but research has found the hormone relaxin - a hormone that targets tissue and wears down (and prevents new) collagen - strongly binds to female ACLs and that is something that does not happen in men's ACLs. Other studies then showed a correlation between high relaxin levels and ACL injuries.

Football boots being designed for, and based on, male players was alluded to as another thing not helping the problem by a study published late last year in the Sports Engineering journal. Biological concerns were raised by the group of medical professionals and elite women's staff pointing to the need for them - and other technology in the game - to be tailored to female players.

The less popular option, and likely more costly one, emerging after more than 20 years of research that has not succeeded in reducing the prevalence of ACL injuries in female athletes is looking at the role gender plays instead.

A 2021 study published in the British Journal of Sports Medicine concluded that since prevention tactics based on biological differences had not decreased the disparity between the injury in the two sexes, researching it through a gendered lens could lead to answers and inform approaches to prevention and treatment.

This would mean looking at gendered factors externally in pre-sport activities, training, competition, research and rehabilitation environments, and considering social constructs that likely influenced many of the risk factors considered biological traits in female athletes, according to Dr Joanne L Parsons' Anterior cruciate ligament injury: towards a gendered environmental approach paper.

Dr Choong said factors like fewer resources and subpar facilities were contributing to its prevalence in female athletes, especially by impacting prevention programs.

"The first step is awareness and that's where research is really important, so finding out why it's happening," she said.

"But then it's that second step of 'Okay, now we know some of the reasons, how are we actually going to fix them?'. Even with injury prevention programmes, we know that they work, but the clubs can't implement them because they don't have the time or training practices.

"They don't have the sports and exercise physiologist, so that support team to help coach the players into doing these injury prevention programmes, then you're missing that second piece of the puzzle that's going to really sort of shift the dial.

"I don't think we're going to find any sort of quick fix. I think it's about identifying all these different issues and making headway into each of them and to try and bring that number down over the next period of years."

The increasing profile and coverage of women's sports over the last several years is also helping to close the ACL gender gap.

Medibank launched 'the club no one wants to join', ACL United, last year featuring high-profile athletes like Australian basketball star Lauren Jackson to draw awareness to the injury and provide educational resources.

Similarly, high-profile footballers like Kerr, Leah Williamson, Alexia Putellas, Beth Mead, Vivianne Miedema and more succumbing to the injury bring further awareness to it and help drive change.

But those stars likely won't get to reap the rewards from that, the next generation of stars will.

"Australia has the highest rate of ACL injuries in the world and maybe people aren't necessarily aware of that," Dr Choong said.

"I think a lot of it is tied to our participation rates, which is great. We do want our community to be active and healthy and have all of the great things that go along with playing sports - not just physical but also the emotional and social connections - but we need to find a way to do that and allow people to pay and complete in a way that's going to reduce the risk of becoming injured.

"So when you do have high-profile athletes that people look up to and they see them as aspirational or inspirational, then they pay more attention to what's going on. When we bring awareness to a cause, we generate more interest and therefore we also generate more funding, which is really important for research.

Kerr's latest knee injury came at age 30, but it wasn't her first ACL injury.

The Chelsea star first came back in August 2011 as a 17-year-old, forcing her to miss the 2012 London Olympics several months later.

Dr Choong said research found the peak time for injury rates in female athletes was around the 15 to 19-year-old age group.

"It's happening to young girls and there's a reason why that might be," she said.

"Participation drops off as you get older and probably a good chunk of that is because they stopped participating in sport, which is a really suboptimal outcome.

"But you can have repetitive injuries. So damaging your ACL once doesn't mean you can't do it again, and if you aren't learning or you're not developing the muscles, the strength or the technique to keep that safe, then you're going to have an increased risk of injury."

When news broke of the Matildas captain's injury this month, many Australians and fans of the striker went searching for information.

'How long will she be out? What are her treatment options? Can I donate my ACL to her?'.

Treatment options, in particular, have been a big point of contention.

Last year, findings published in the BJSM looked at 80 people treated with a new non-surgical bracing treatment - Cross Bracing Protocol - and found 90 per cent had evidence of ACL healing three months after their ruptures.

Another study published in the BJSM, which was led by a University of Melbourne senior research associate, compared 120 patients who went down either the surgical or non-surgical treatment route and found 30 per cent of ACLs could heal with exercise-based rehabilitation.

Both studies reported those who had ACL healing via non-surgical means, had better outcomes than those treated with surgery.

With those findings in their infancy, Kerr underwent surgery for her injury, presumably under the guidance of some of the best medical experts available through her WSL club Chelsea.

Dr Choong said return times for non-surgical intervention weren't necessarily faster but pointed towards "less risk of developing osteoarthritis down the track".

"There's a lot of research out there at the moment looking at what are the different treatment options for an ACL injury. Australia has the highest rates of surgery for ACL injury in the world, it's pretty stark actually," she told Optus Sport.

"So 90% of Australians who have an ACL injury will have reconstructive surgery for that, but there are other types of treatment that people can have primarily based on active rehabilitation like physical activity, physical exercise, and we're seeing some evidence that these conservative options for treatment are just as good as surgical options."

Originally published for Optus Sport on January 20, 2024