It is no surprise that England is in the final of the Women’s World Cup. They are the world’s fourth-ranked team, the reigning European champions, and were among the semifinalists at the World Cup four years ago. The final was the expectation, not the goal. When England dominated Germany in the Euro finals last September, there were more than eighty-seven thousand fans at Wembley Stadium. England beat the United States at a friendly a month later, and some seventy-seven thousand people came to watch.

And yet that team is not this one. The revelation of that roster was Beth Mead, who established herself as an almost unstoppable force in a dazzling display at the Euros, winning the Golden Boot for most goals and the Golden Ball for the tournament’s best player. In November, she tore her A.C.L. A few months later, England’s captain, Leah Williamson, bent her leg awkwardly as she came over the ball on a challenge in a game for her club team, Arsenal. Face down on the field, she threw up a hand to signal for help, then pounded the earth in obvious pain and frustration. Surely, she knew, even then—before she limped from the pitch, supported by medics; before the MRI confirmed the grim diagnosis; before the surgery—that she’d torn her A.C.L. Everyone knew. Everyone had seen it happen too many times before.

In early May, the England midfielder Fran Kirby, a two-time F.A. player of the year, announced that she, too, would be undergoing surgery to repair an injured knee, and would miss the World Cup. And the tournament had hardly started when Keira Walsh, the team’s fulcrum in the midfield, went down with a leg injury. “I’ve done my knee,” she reportedly told medical staff as she was carried away on a stretcher. When it was announced that her A.C.L. was, in fact, still intact, and that she would be able to return—in the end, she missed only a game and a half—the news was presented as a kind of miracle.

Even without these players, England is still a phenomenal team. It overcame a surging Australia—propelled by the passion of the home country’s fans and the unstoppable force of Sam Kerr—with ruthless, clinical play, despite missing yet another star: the dynamite young forward Lauren James, who had to sit out for two games after receiving a red card for stomping on a Nigerian player, Michelle Alozie. But England has been gritting out wins, not racing to them. It’s tempting to wonder what the team would look like if not for the rash of ligament ruptures.

But you could say that of several teams. England is far from the only one dealing with A.C.L. injuries. The Netherlands, last year’s finalist, might have gone further than the quarterfinals if they’d had their best player, Vivianne Miedema, who tore her A.C.L. last winter. The United States’ inability to score goals is less shocking when you consider that Catarina Macario, perhaps their best player, was out with a torn A.C.L. (Their top goal scorer in 2023, Mallory Swanson, missed the tournament, too, with a torn patellar tendon.) Canada, the reigning Olympic champions, lost their star forward, Janine Beckie, to an A.C.L. tear in March. France’s Marie-Antoinette Katoto, a nominee for the 2022 Ballon d’Or, tore her A.C.L. last year. Her French teammate Delphine Cascarino tore hers in May. The list goes on. Myriad factors have played into the chaos and surprise of this World Cup—none of the four semifinalists has ever won the championship—but the ripple effect of A.C.L. injuries is one of the biggest. You might even call it a crisis—if it were anything new.

The anterior cruciate ligament is a thick band of tissue connecting the thigh bone (the femur) to the shinbone (the tibia). It’s found inside the knee joint, in front of the posterior cruciate ligament (P.C.L.), which it crosses to form a kind of sturdy “X.” The A.C.L. keeps the shinbone from sliding in front of the thigh bone and keeps the knee in place. But when it is stressed in certain ways—during a quick pivot, for instance, or an awkward landing or sudden impact—it can rip. When that happens, the knee loses stability. After a full rupture, it generally won’t regenerate or heal on its own. Instead, doctors will take a portion of the patient’s hamstring, quadriceps, or patellar tendon, or tissue from an organ donor, and graft it into the knee to create a new A.C.L.

This can work well, particularly if you have access to top-flight doctors, as most professional athletes do. But it is painful, and recovery is long and arduous. It’s expensive, too, if you’re footing the bill: out-of-pocket costs in the U.S. can be upward of ten thousand dollars. Full recovery can take anywhere from nine months to more than a year—an eternity in the short life of an élite athlete. Even when an athlete regains most of her form, the reconstructed knee can be vulnerable. A significant percentage of athletes who have torn their A.C.L. once do it again within a few years. Around half develop osteoarthritis five to fifteen years after surgery. People who tear their A.C.L.s are around seven times more likely to need a total knee replacement down the road. And, no matter how common the surgery has become, the healing process can be unpredictable. Christen Press, a key player on the U.S. team that won the 2019 World Cup, recently underwent her fourth operation on a knee that she tore up last year.

Male athletes tear their A.C.L.s, too, in alarming numbers—in the Premier League earlier this month, Jurrien Timber had barely stepped on the field after a flashy, forty-million-dollar transfer to Arsenal when he damaged his. But the rate is significantly higher among female athletes, particularly in sports that involve sudden stops, pivots, and accelerations. Just how much higher is unclear. (Kathryn Ackerman, a doctor specializing in sports medicine—she runs the Wu Tsai Female Athlete Program at Boston Children’s Hospital—told me that women are four to six times more likely than men to tear their A.C.L.s.) Why there is such a difference is not entirely clear, either. There are morphological factors: women often have a smaller notch on their femurs than men, which gives the ligament less leeway when stretched; they typically have wider hips, which changes the angle of the femur. Women tend to have stronger quadriceps relative to their hamstrings, and to land more flat-footed and with stiffer knees. There is a strong suspicion that menstrual cycles increase the risk of ruptures, by affecting ligament laxity, but, as is the case with so many medical issues affecting women, the theory has not been the subject of sufficient rigorous study.

Still, biology is not destiny, and for too long it was treated as such. The Football Association, English soccer’s governing body, banned women’s teams in 1921, stating “the game of football is quite unsuitable for females and ought not to be encouraged.” The ban was not lifted until 1970. A narrow focus on how the morphology of women affects injury rates not only runs the risk of deterring girls from competing in the first place; it also threatens to reinforce the false idea that sports are unsuitable for women, while ignoring crucial social and cultural factors. For decades, women have often played on inferior fields, which is known to increase the risk of non-contact leg injuries. (This was a sticking point for the U.S. women’s national team in their fight for equal pay and conditions.) They have played without sufficient medical infrastructure or training support. They have participated in training programs that are insufficient for their needs. As opportunities and access have expanded, the quality of their environment hasn’t quite kept pace.

England’s domestic league wasn’t fully professional until five years ago. Since then, traditional powerhouses—Chelsea, Arsenal, Manchester City, Manchester United, and so on—have begun investing more of their resources and influence in the women’s game, to tremendous effect. Now England’s women’s league and national team both occupy spaces in the upper echelon of international sport. The teams have legitimate television contracts with the BBC and Sky Sports, and receive continual coverage from places like the Guardian and the Athletic. Increasingly, the stars are superstars. The schedule has grown along with demand; players are playing more, and with greater intensity. But that extra load on their legs has consequences. And, even now, at all levels, women’s teams are more likely than men’s teams to travel by coach instead of business class, commercial instead of charter. A National Women’s Soccer League game was once played on a fifty-eight-yard-wide field in a Triple-A baseball stadium. Women typically wear cleats made from molds of men’s feet, and that shape affects how arches and heels are supported when an athlete lands. (This could be especially significant when it comes to A.C.L.s, given the way that perilous ground-foot interactions can stress the knee.) They are often, even at the élite level, supported by smaller medical staff, with less training, than the men receive.

The disparity in resources extends down through the youth levels. That, in fact, is where some of the biggest problems are. For all the attention that A.C.L. injuries among élite players are getting, many of the hundreds of thousands that occur each year happen to younger players. Generally, girls are at high risk of A.C.L. injuries after they have gone through puberty but before they have built up their strength. The first time that the U.S. national team member Emily Fox tore her A.C.L., she was a freshman in college. Megan Rapinoe tore hers three times, the first as a college sophomore. Alex Morgan tore hers in high school. And they are the lucky ones: many younger athletes, who don’t have the access to doctors and rehabilitation programs that top athletes do—or who are simply, and understandably, traumatized by their injury—quit the sport they were playing when they were hurt. Some quit sports altogether.