The ACL Crisis in Women's Soccer Part 1: Risk Factors
Women's fútbol globally is experiencing a surge of anterior cruciate ligament (ACL) injuries. This series will look at what's causing it, and what can be done to combat it.
This is the first of a series that will look at why we’re seeing an uptick in anterior cruciate ligament (ACL) injuries in women’s fútbol globally, how it can be prevented, and what clubs are doing already to prevent these injuries and help players who have suffered them return from them.
With the World Cup starting in less than a month, the talk of who isn’t going is almost as loud as about who is going. A laundry list comprising some of the world’s best players will miss the tournament due to anterior cruciate ligament (ACL) injuries. How can something just over an inch long fell such giants of the game?
The ACL is “one of the primary ligaments in the tibiofemoral joint and acts to stabilize the knee under multiple loading conditions” (NIH), or in layman’s terms is one of a series of ligaments that keeps the parts of your leg above and below your knee in line, not allowing for what we think of as an unnatural motion. This in turn helps us walk and run with confidence that our leg won’t bend the wrong way.
Dr. Holly Silvers-Granelli is one of the world’s leading experts on the ACL in the context of soccer and sports in general. Dr. Silvers-Granelli has been a physical therapist for the US Men’s National Team, US Women’s National Team, LA Galaxy and Chivas USA, been an ACL Prevention Medical Consultant for Barcelona, US Soccer’s ACL Prevention Task Force, the National Football League’s ACL Musculoskeletal Task Force Committee and FIFA Women’s Development Programme’s Football Health Committee.
During an hour-long interview, Dr. Silvers-Granelli tells Golazo del Gringo that in the 1990’s in conjunction with Dr. Bert Mandelbaum, “we established that there were four categorical risk factors for ACL injuries… anatomical risk factors, environmental risk factors, hormonal risk factors which are unique to women, and biomechanical risk factors.”
“And now in the last two decades,” she continues, “we’ve expanded that to include genetic risk factors and also resource risk factors.” Of course some of these risks are easier to overcome than others, and some risks aren’t as critical as others as well.
For instance, anatomical and genetic risk factors can’t be altered in players, and in dystopian scenarios could conceivably be held against players who may have these risk factors despite them never presenting an issue. Even under less horrific circumstances, there isn’t anything that can be done about how someone’s body is.
Dr. James “Hash” Hashimoto is also a world renowned ACL specialist with an impeccable résumé, serving as Head Athletic Trainer and Physical Therapist for the U.S. Men’s Olympic Soccer Team. He was referred to as “US Soccer’s Miracle Trainer” in a 2015 article in VICE magazine. During an interview with Golazo del Gringo, Dr. Hashimoto acknowledged that while structure was a factor but stressed what most doctors focused on were “mainly the mechanics,” especially around two critical areas: landing and decelerating. He spoke about the anatomical differences in men and women athletes and how that could have an impact, especially with the ACL.
When asked if there were significant physiological differences in men’s knees and women’s knees that would explain why women were experiencing this at the rate they are, Dr. Hashimoto said “it's not that simple,” he says flatly. While yes there are some physiological differences in the knees themselves, there’s a lot more to it than just that.
“Women have a wider pelvis,” he explained, “so your angles are going to be different in how you attenuate forces.” And it’s these differences in how forces are attenuated where women become more susceptible to injuries.
Dr. Hashimoto went on to say “Some of the technical factors that are really kind of looked at are really landing, deceleration, and the mechanics of those things. So if you look at how a female athlete jumps and lands, or how a female athlete decelerates, the mechanics of how they do it are different and don't attenuate the forces as well. And the knee takes the load.”
The science is always evolving, too. “We used to look at a ratio of quad versus hamstring strength. And if you were within a certain parameter, you were considered more balanced. The thought is hamstrings are dynamic stabilizer for, for ACL. And that with female athletes, they had a greater ratio difference in strength between their quads and their hamstrings. But I think, from my standpoint, experientially, I think the biggest thing is really the, mechanics of deceleration and landing.”
Hormonal risks for women also occur, with menstrual cycles effecting ligamentous laxity, or the amount of slack ligaments have. Dr. Silvers-Granelli tells Golazo del Gringo that during ovulation, women and girls get a huge peak of estrogen and then a couple of days later in the luteal phase they get a peak of progesterone, and while it depends on the individual and how high their peaks are, it’s during those peaks that “you actually get a little bit of ligamentous laxity. And this is this is ubiquitous throughout the body.”
Dr. Silvers-Granelli goes on to say that “there have been some interesting studies that have been done over the last 20 years showing that injury rates are a little higher during ovulation,” but also that despite the groundbreaking work at the professional level by people like Dr. Dawn Scott and Dr. Georgie Bruinvels, Dr. Silvers-Granelli says “we don't have the sports scientists available, nor the resources to do that on the larger, broader scale.”
As in almost every other avenue of life, some of the environmental and resource risk factors are inextricably linked. Playing on artificial turf as opposed to natural grass is both an environmental and resource risk, with more affluent teams often playing only on natural grass. That said however, it isn’t as clear-cut a risk as it may seem. “The literature (is) sort of all over the map,” according to Dr. Silvers-Granelli, who pointed out that “athletes adapt (even) subconsciously when they’re (not) on grass, so the game is a little bit slower,” in terms of motions like cutting and decelerating. This could account in part for the data not being as clear as expected when it comes to the two surfaces.
Resources (and lack thereof) however do have an impact on ACL injuries. It’s not just players from less-affluent backgrounds that struggle with resources however, it’s all women and girls. A June 2023 article in The Guardian talked about how “boots (soccer cleats) have tended to be marketed towards women without being truly designed for them,” with Ida Sports “releasing its first boot (designed specifically for women) in 2020.”
Most cleats aren’t designed with the subtle but real differences between men’s and women’s feet in mind, and as we’ve seen, these tiny differences can have big impacts on a holistic level. Instead, women’s cleats are usually cleats designed for men and repackaged in a process derisively called “pink it and shrink it”. Dr. Silvers-Granelli points out that “the cut on the jerseys is a little different for women. So why would we expect a shoe to be worn equally by gender?”
She goes on to say that it’s incumbent upon the big shoe companies to step up and make cleats specifically designed for women that account for anatomical differences. “There's a huge audience, (and) there's a lot of money to be made. So it'd be it would behoove them to put in the research.”
Not any one of these risk factors by themselves can be pinned as the sole cause of the uptick in women’s soccer injuries. But reducing any or all of them should help ensure a safer environment for players.
In the next installment, we’ll explore what the doctors recommend to help prevent ACL injuries in players of all ages.