Preventing Lower Extremity Injury in Female Soccer Players
As a podiatric surgeon practicing in an orthopedic sports medicine office, I have had the privilege of working with and treating high school, collegiate, and professional athletes for the past 16 years. In 2022 and 2023, I had the opportunity to travel the world, providing education to professional female soccer players in countries like England, Jordan, and Greece. With the ongoing anterior cruciate ligament (ACL) injury epidemic in women’s soccer (football), many national organizations and teams continue to look for answers on how to keep their players safe and healthy. Many research studies show that female soccer players are 4–8 times more likely to tear their ACL than their male counterparts.1
My main objective when speaking to professional female soccer players and coaches is to provide education on why female athletes are at higher risk for lower extremity injury, and what players, coaches, trainers, and doctors can do to help mitigate this risk. During my travels, it became very apparent that most players and coaches, even on a professional level, are unaware of how different internal and external factors can play a major role in increasing the risk for injury in female athletes.
The incidence of ACL injury tear in female soccer players has increased significantly over the past 5 years. Just in 2022 alone, 57 players in the top 6 leagues in the world have torn their ACL.2 Of these, 5 players were in the top 20 at the Ballon d’Or. Some of these well-known professional players include the award’s 2022 winner, Alexia Putellas from Spain, Catarina Macariao and Tierna Davidson from the USA, Vivianne Miedema from the Netherlands, Marie-Antionette Katoto from France, Sara Dabritz from Germany, Simone Magill from Ireland, and Beth Meade and Aoife Mannion (2 ACL injuries) from England.2
Apart from a record number of international female soccer players reporting this injury, incidence has also increased on the collegiate and high school levels. According to Montalvo and colleagues, 1 in 19 high school and collegiate females playing soccer ruptured their ACL in 2019.3
In addition, the most common injury in NCAA female soccer players is ankle sprain, at an 8.6% incidence.4 Female high school soccer players who have more than one concussion carry a higher risk of lower extremity sprain or strain.5
With the increased popularity of women’s soccer, worldwide there were 945,068 female soccer players registered with FIFA in 2022.6 Over the years, there has been a significant increase in ACL surgeries on female athletes, costing more than $650 million annually.7 In a recent study by Lopez-Valenciano and colleagues, female lower extremity injuries had the highest rate of incidence compared to other parts of the body.8
Although many studies demonstrate that female soccer players are at increased risk for lower extremity injury than males, the real question is why?
A Closer Look at Soccer Injury Risk Factors in Women
Factors that may increase the risk of a female athlete’s injury include anatomic differences, neuromuscular differences, hormones, and environmental factors.
Anatomy. The Q angle, femoral notch, tibial torsion, and pronation can all play a role in the increased injury rate in female versus male athletes. The Q angle is the line from the anterior superior iliac spine (ASIS) of the pelvis to the center of the patella (kneecap) with a second line from the patella to the tibial tubercle. A normal Q angle is 12–20 degrees. Males tend to be on the lower end of this angle, at about 12–14 degrees, and females on the upper end of the angle between 17–20 degrees. Women’s larger Q angle leads to increased knee valgus, increased pronation of the foot, and internal rotation of the tibia; thus placing more pressure on the medial side of the knee and ACL ligament.9
A second lower extremity anatomical factor that is different in men and women is the femoral notch, the area on the femur where the ACL attaches. The femoral notch is usually smaller in females than in males, which means a smaller ACL. Narrower notches have a higher incidence of ACL injuries due to higher torque against a hyperextended knee.10
Neuromuscular differences. Gender differences in neuromuscular activation can contribute to ACL injury. Men’s quadricep tendons and hamstrings are usually stronger, giving men greater knee stabilization and lower incidence of knee injury. Females have quadricep dominance, which increases knee extension movements when compared to flexion. Female athletes land a jump with their bodies more upright and the knees straight and inward secondary to their quadriceps being stronger when compared to the hamstring muscles. This extension puts more strain on the anterior and medial knee when landing from a jump and can increase the incidence of ACL injury.11
Hormones. Recent studies show that the menstrual cycle and hormone fluctuation may play a role in increased ligament injury rates. The menstrual cycle breaks down into 4 phases. Phase 1 is from the first day of a woman’s period to the last day of the period, days 1–5. Phase 2 is from the last day of the period to just before ovulation, days 6–14. During phase 2, estrogen levels increase and progesterone levels are low. Phase 3 is from ovulation until hormones decrease, days 15–23. Estrogen levels are low and progesterone levels become higher during phase 3. Phase 4 of the menstrual cycle is the days right before the period when women have decreased progesterone and estrogen, days 24–28.12
Females may be higher risk for ligament injury during the late phase 2, also known as the late follicular phase of the menstrual cycle, just before ovulation. During late phase 2, estrogen levels are highest, progesterone levels are low, and ligaments are loosest.12 Enhanced ligamentous laxity in female athletes increases the risk for ligament tear. During late phase 2 of the menstrual cycle, ligaments have more laxity, and this will affect an athlete’s neuromuscular control and movements on the field, increasing the risk of a non-contact ACL tear or ligament injury. A study by Martin and colleagues tracked international soccer players for 4 years and their injury rates in relation to their menstrual cycle phase.12 The study conclusion showed an injury incident rate for tendon and muscle injury to be 88% greater in the late follicular phase of the cycle when compared to the follicular and luteal phases. Of note, some studies have shown that hormonal contraceptives may decrease the risk of ligament injury by controlling hormonal flux during phase 2 of the cycle.13
Environmental. Soccer playing surfaces can increase injury risk. Artificial turf may cause increased frictional forces leading to increased knee injury in women. Inconsistent training surfaces, especially in United States youth soccer, can also contribute to trauma. Training on grass but playing on turf and vice versa is bad for any athlete, no matter the sport. A 2022 study showed that female soccer players had a significantly higher risk of non-contact ACL injury on artificial turf versus grass, but there was no real difference in male players.14 Richards first described the historic significance to the non-contact ACL injury, otherwise known as the plant-and-turn injury, in 1973.15 They discovered that male American football players were being diagnosed with non-contact “knee sprains” that became increasingly unstable despite conservative therapy. Richards took several football players to the operating room to explore the knee sprains and discovered intraoperatively that every one of these athletes had sustained an ACL tear. This intraoperative discovery was before the advent of advanced imaging technology such as magnetic resonance imaging (MRI) and computed tomography (CT) scans.
Improper shoe gear and cleat length can also cause an increased risk for knee ligament injury. If the stud on a shoe is too long and the athlete is playing on a turf field, there is a higher likelihood of getting the cleat stuck in the turf and not turning with the leg. This will lead to a non-contact ACL tear as described above. Athletes should have different cleats for different playing surfaces. The regular soccer cleat is designed for a grass field. A hard ground grass stud is too long for the artificial turf surface and can get stuck in the turf, causing plant-and-turn ACL and potentially other types of lower extremity ligament injuries, as well. Soccer players and coaches should be aware of this difference to help reduce the rate of injury.
Female players are usually not aware that most soccer shoes on the market are made specifically for men. Cleats in the women’s section at local shoe stores are the same male shoe, made on the same male last, just with different pink or purple colors focused on the female consumer. With different female foot and lower extremity anatomy such as increased Q angle, tibial torsion, and increased pronation, women should have the option to buy cleats made specifically for their gender. Professional female soccer players around the world are now demanding gender-specific soccer cleats, and shoe companies are slowly responding. One of the first female soccer cleats on the international market is by a company called IDA. This cleat is designed specifically for female soccer players, using a last from female foot anatomy, improved arch support to decrease pressure on the medial knee, and a wider toe box to prevent toenail loss.16 Other companies are conducting their own research to catch up and create similar products that will provide better fit, support, and protection for female athletes.
Tips for Soccer Injury Prevention in Female Athletes
The biggest gap in existing knowledge regarding women soccer players and lower extremity injury is the lack of data. We know women are being injured 4 to 8 times more than male soccer players, but we do not know exactly why this is happening. Theories that I have touched on include anatomical differences, neuromuscular differences, hormonal fluctuation, greater risk with certain playing surfaces, cleat stud length, and poor shoe gear for women.
However, the bottom line is adequate data is not yet available to help medical experts develop specific prevention and treatment protocols. As more studies are being done at high levels of academia, US Soccer, UEFA, and FIFA, our role as physicians, coaches, trainers, and parents is to provide education on injury prevention for our female soccer players. Education and prevention protocols must start at the youth level.
An excellent example of a preseason and continued in-season training program is the FIFA 11+ program. This program was developed in 2006 in cooperation with the Santa Monica Sports Medicine Foundation (SMSMF), and the Oslo Sports Trauma and Research Centre (OSTRC), as a complete warm-up program to prevent injuries in amateur soccer players.14 The efficacy of FIFA 11+ was first evident in young female players. A 2017 study found a significant reduction (up to 30%) of injuries in female soccer players when they performed warm-up exercises at least twice a week; injury risk was lowest in those players with higher adherence to the program.15
Hormone tracking is also a tool for elite level soccer players. Dawn Scott, the high-performance coach for the 2019 US Women’s National Team, credits period tracking, diet, and workout modification around each athlete’s cycle, as a breakthrough method that led to the team winning their fourth World Cup.19
Girls and women have different anatomy, different landing patterns, and different hormones than males. They must train differently than boys and men and wear cleats specific for the female anatomy.
Injury prevention recommendations from my experience for female athletes are listed in Table 1 below.
In Conclusion
With proper female-specific strength and conditioning programs such as the FIFA 11+ program, appropriate cleat length for playing surfaces, soccer cleats made for female anatomy, consistent playing surfaces, and education on the menstrual cycle with training and nutrition guidelines, we can work to mitigate ACL and lower extremity injury rates.
Karli Richards, DPM, MHA, FACFAS, CWSP, is affiliated with the Department of Orthopedics and Podiatry at UPMC-Richards Orthopaedic Center & Sports Medicine.
References
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