The hidden opponent: How ACL tears threaten women’s soccer

ACL injuries are sidelining women and girls from the World Cup to the playground.

Written by Anoushka Oke, Sports Editor
Design by Sofia Stankovic

As the 2023 Women’s Soccer World Cup kicked off Down Under, a shadow loomed over the tournament for players and fans alike: The absence of many of the game’s most electrifying stars. 

Notable absentees included Canada’s Janine Beckie, England’s Leah Williamson, and the United States’ Catarina Macario. They were missing not due to a lack of skill or determination, but by a common and devastating injury: A torn anterior cruciate ligament (ACL). 

The injured stars were just three of the many players who had torn their ACL during their club seasons, thereby side-lining them for the international tournament. They are just a small part of a concerning trend with ACL injuries disrupting women’s soccer.

ACL injuries in women athletes

The ACL, a ligament located in the middle of the knee, connects the patella, or kneecap, to the tibia, the shin bone. Its main function is to ensure knee stability and balance, which is crucial for movement. However, the ligament is susceptible to tearing, a common yet serious injury typically resulting from rigorous physical activity. For instance, when running, stopping quickly and changing directions can cause an ACL to tear.

Sustaining an ACL injury is devastating for an athlete, frequently requiring surgery to reconstruct the ACL to prevent future injury and thus pushing them out of action for some nine to 12 months. The recovery period is so long because following surgery, athletes face the daunting task of regaining lost muscle mass, restoring mobility, and overcoming psychological hurdles from fear of re-injury. Avoiding surgery also runs the risk of sustaining another injury because daily activities such as walking up the stairs or stepping off the curb can lead the knee to buckle, causing the injured person to fall.

“You need an ACL reconstruction because your knee is unstable,” Dr. Moreno Morelli, a faculty lecturer in McGill’s Department of Orthopaedic Surgery, explained. “An unstable knee also causes a lot more stress inside the joint, so there’s a greater risk of having additional damage to the inside of your knee.”

In my years of playing youth soccer, my coaches consistently drilled the heightened risk of ACL tears in women and girls into our heads. Experts from Yale Medicine state that women are two to eight times more likely to experience an ACL tear than men are. When I stopped playing soccer after my sophomore year of high school, the fear of sustaining the injury stopped lingering in the back of my mind. 

“As [people assigned female at birth] start to grow, [the] pelvis changes shape, and it changes the alignment of [the] legs,” Morelli said. “So it puts you more into what you call a valgus position or knock-knees alignment, and that kind of alignment puts more strain on your ACL. As soon as you push off the limb or land on the limb when the leg is in that knock-knees position, it puts more strain on the ACL, and it could rupture.”

This strain becomes exacerbated by a larger Q angle in women—normally around 17 compared to 12 degrees in men—due to pelvis shape differences. The Q angle measures the angle between the line from the knee up the femur and an imaginary line connecting the knee with the bottom part of the pelvis. This larger angle also puts more pressure on the ACL, increasing the risk of injury.

Research from 2017 also suggests that hormonal fluctuations during the menstrual cycle increase ACL tear risk, as it has been shown that elevated estrogen and progesterone cause the hormone relaxin, which loosens ligaments, to be more active. The greater ligament laxity, or looseness, makes the joint less stable, increasing the risk of injury. However, despite this observed connection between the menstrual cycle and increased ACL tears, we still lack definitive evidence.

Research gaps

A deficit in data and research on the increased ACL risk among women leads athletes to keep getting injured. According to Alireza Monajati, a senior lecturer in the University of East London’s Department of Bioscience and Sport, there is currently not enough data related to the circumstances surrounding ACL injuries. These gaps in the research make it more difficult for doctors and trainers to analyze the causes of the injury. There are also limited studies with high internal validity that detail ACL injuries in elite female athletes, so how can we find available research that could be used for preventative measures?

More data on elite female athletes will help develop better training and nutrition plans. For instance, should evidence conclusively establish a link between ACL injuries and the menstrual cycle, it would provide compelling cause for managers at elite clubs to tailor menstruating players’ training and match loads based on their cycles. However, this approach might also overreach into players’ intimate lives, giving coaches too much access to their bodies; in the pursuit of more complete data, research ethics is also crucial.

In an interview with The Tribune, Monajati discussed the challenges in gathering data on ACL injuries among athletes. 

“Experimental research on professional [athletes] is limited because of their availability, but in terms of the type of research, it doesn’t always have to be experimental research [where] you bring the professional athlete to the lab,” Monajati said. “Sometimes it's just gathering the data around the event where the injury happened, and when you have a big pool of data, then you can make the right decisions.”

To enhance this process, Monajati proposed a procedure that he believed would enable greater collection of such data in women’s soccer, inspired by the existing protocols for cardiac risk management in soccer. According to these protocols, set by governing bodies like the FA and UEFA, players participating in European or FIFA competitions are required to undergo cardiac screening every two years as a condition to play. Monajati believes a similar approach can be done for ACL tears.

“They should undergo certain screening every one or two years, and when injuries happen, the data of that must be reported by the medical team to the FA. The data can involve so many things, [like] the load of the training, the surface where they’re playing, [and] the menstrual cycle phase they’re in. All of this data can be gathered so that you have a big [set of] data eventually, and with big data, you can then apply statistical analysis to process and find the patterns.”

Professionalization and inadequate medical care

Beyond gaps in data, women’s clubs’ frequent lack of sufficient resources puts players at risk of increased ACL tears. In theory, the more at-risk demographic should be offered extra protection and preventative measures, such as supportive exercises and nutrition. However, this is not the case. 

A typical women’s soccer regular season is between 20-30 games depending on the number of teams in the league—National Women’s Soccer League (United States) teams play 28 games, while the Women’s Super League (England) and the Frauen-Bundesliga (Germany) play 22. This doesn’t factor in extra tournaments, like domestic cup games or the Champions League, and the intensity only heightens for players who also compete with their country’s national team. Samantha Kerr, one of the best women’s soccer players, competed in 38 games for Chelsea in the 2022-23 season and 12 games for Australia in 2023. 

In recent years, women’s soccer has been working toward greater professionalization to bring it up to the standard that men’s teams play at. In that process, the women’s teams have been playing a growing number of matches. Several global invitational tournaments that women players can compete in have grown in the past ten years, from the Arnold Clark Cup (2022) to the Cup of Nations (2019) to the SheBelievesCup (2016). Pre-existing competitions have also welcomed more teams, increasing the game count. In 2011, the World Cup featured 16 teams; the 2023 World Cup included 32.

However, as playing time increases, medical support has failed to keep pace. According to a FIFA report from 2021, more than 25 per cent of first-division women’s soccer teams did not hire a physio or a team doctor. Christina Le, a physiotherapist at the University of Alberta’s Glen Sather Sports Medicine Clinic and a passionate Arsenal fan, discussed the state of medical staff availability at women's soccer clubs in an interview with The Tribune.

“Even clubs like Arsenal and Chelsea are just now starting to support their women’s sides better. I don’t think there were any full-time physios and stuff like that that were part of the [women’s] clubs until maybe the last couple of years,” she said. “So I think that’s a big thing: Just trying to get a steady medical team instead of contracting a physio just for the season or just for like three months, [because otherwise] you have to build a whole new relationship with somebody else who comes in and takes over that role and maybe has a totally different treatment approach and style.”

Le believes the lack of permanent staff members is largely tied to the way that soccer fans and even club employees still see the women’s game as second-tier to the men’s.

“When they’re trying to pursue these sports [medicine] jobs, there are a lot of people who look at the women’s league as a stepping stone to get to the men’s league,” Le said. “That is not how this should work. They are different entities, and the women’s game should be the end goal for somebody. It shouldn’t be like people get their ‘in’ at a club by helping out with the women’s team and eventually get a promotion to the men’s side.”

Similar pressures appear in the coaching context. The media linked England Lionesses manager Sarina Wiegman to the England men’s coaching job in August, while broadcasters repeatedly asked Chelsea F. C. Women manager Emma Hayes if she would switch to coach in the Men’s Premier League. In both cases, the move to the men’s side is seen as a step up by the media and by fans—despite the fact that their teams had more successful years than the corresponding men’s teams. 

In an interview with Sky Sports, Lioness Georgia Stanway responded to rumours of Wiegman being linked to join men’s soccer coaching roles by emphasizing that managers enjoying their roles in women’s soccer is what will allow it to continue to grow—they should not view women’s teams as a stepping stone. Hayes had a similar reaction to the rumours, telling an interviewer that Wiegman’s role as a women’s coach is important in and of itself and that women’s teams deserved top-tier coaches just as much as men’s teams do. Similarly, women’s teams also deserve top-tier medical staff.

Prevention Strategies

To address the disproportionately high risk of ACL tears, experts and sports professionals alike are emphasizing the need for comprehensive medical support. This focus pushes to overcome the physiological factors that uniquely, adversely affect women. A starting point is incorporating preventative exercise programs, which have demonstrated efficacy in reducing ACL injuries.

“There are several studies that have looked [at] specific exercise programs with the intent of decreasing the incidence of ACL tears,” Morelli said. “There’s a big study out of Los Angeles that was published almost ten years ago where they looked at about 1500 [14-18 year old female athletes] who did a specific exercise program and compared [them] to those who didn’t do the exercise program, and the exercise program reduced the incidence of ACL tears by about 80 per cent. They carried this study out over two years, and in the second year, it reduced by 70 per cent.”

But to build a solid foundation, young women pursuing elite soccer need adequate exposure to high-level training early on. Bad running form, for example—which entails habits like heel striking and overstriding—can lead to running-related injuries. Training that builds good patterns related to form and strengthens players’ bodies in a way that fortifies them against ACL injuries is essential.

“There’s a lot of attention put on the biological pieces, and I think it absolutely makes sense to integrate a part of that, but I think the tricky part with the biological pieces is that they’re not modifiable,” Le said. 

She explained that non-biological factors like having a medical team and access to proper strength and conditioning help. 

“In England at all of these big clubs, there are boys who are like nine and ten years old being signed to academies and then getting exposed to strength and movement patterns at that age. There’s not much of an academy for a lot of the women’s clubs, and if there are, they are a little bit older, maybe 15 or 16.”

According to Monajati, an injury-prevention program targeting ACL tears combines improving coordination, balance, and strength. 

“The framework of that is basically these three aspects: The technique during landing and changing directions, which is something that can be taught, the balance in the lower limb muscles, which comes from strength and conditioning, and perception exercises, to improve coordination,” Monajati said.

Physiological factors that increase women’s risk of ACL tears are not an excuse for the elevated frequency of the injury in the women’s game. Rather, they offer a call for increased attention, research, and data related to professional women’s soccer that will allow for the establishment of more adequate preventative measures.

Without preventative measures that target ACL tear risks, women soccer players will continue to miss out on momentous opportunities like the World Cup—devastating both players and fans.