ACL injuries benching women

Two hundred million players in 186 countries will play soccer, the most popular sport in the world, this year. With the season fast approaching the risk of injury is creeping up, and for women one particular injury is playing the gender card. Anterior Cruciate Ligament (ACL) tears are two to three times more likely to happen to women than men, and unfortunately, there is no single cause to blame.

“It’s multi-factorial, a combination of all the above and some factors might be causing it more in certain individuals than others. But it doesn’t mean women should stop playing,” says Dr. Daniel Benoit, a professor at the University of Ottawa’s school of human kinetics.

The ACL is one of the many ligaments in the knee. It’s responsible for holding the femur and the tibia together. It is one of the most important ligaments because it helps prevent hyperextension, anterior translation of the tibia where the tibia slides forward in relation to the femur, and rotation of the knee.

“We see the injury a lot in soccer players, gymnasts, and hockey players because of the movements. The ligament is very vulnerable to the rotation and sudden cutting we do in those sports,” says Marie-Elise Samson Buchan, a physiotherapist at The Sports Therapy Clinic at Carleton University.

The most suggested cause is the Q-angle. The Q-angle describes the angle made when the femur does not connect to the tibia in a direct line. This happens in women because their larger hips put more stress on the knee and cause internal rotation of the femur. The Q-angle is often much more severe in women and this can put extra stress on the ACL.

“The Q-angle is in a static position but when you move it is called the valgus angle,” says Dr. Mario Lamontagne, a professor at the University of Ottawa’s school of human kinetics. When women jump, cut, or stop suddenly their knee turns in towards the body, creating the valgus angle. The Q-angle is used to describe this angle when a person is standing still and when the angle is created in motion it is called the valgus angle. Dr. Lamontagne says women land jumps and cuts with a more severe valgus angle, putting stress on their ACL.

Neuromuscular

He says another factor is neuromuscular. He found significant differences in the way male’s and female’s muscles react to jumping and cutting when he was studying the calf, thigh, and hamstring using Electromyography (EMG) signals.

“Women have the tendency to have a weaker muscle contraction to prevent the valgus angle,” says Lamontagne. When males hit the ground they contract all their muscles at the same time as they hit. Females, on the other hand, contract their muscles just before hitting the ground so when they actually make contact their muscles are already in a weaker state. The muscles provide less help in stabilizing the knee and stopping a more severe valgus angle.“There’s a lack of synchronization and that might cause the issue,” says Lamontagne.

Another potential cause is the actual muscle difference between women and men. Both women and men have nearly equal twisting and loading forces on their knee when they compete in the same sporting events and at the same levels. However, women tend to have less muscle strength. Muscles that help hold the knee in place are stronger in men than in women and because of this women rely heavily on the ACL to hold the knee together. Younger women are especially susceptible for this reason.

“If you think of muscle strength at that young age you’re not as strong,” says Benoit. Women also tend to have a smaller intercondylar notch, through which the ACL runs, and this can cause the ACL to catch and tear more easily. The ligament itself can also be smaller in women. A smaller ligament is less able to handle the stress of a woman’s hips, Q-angle, and weaker muscles.

Finally, the last and most recent discovery is the potential impact of hormones.

“Risk of injury fluctuates over time during a women’s menstrual cycle,” says Dr. Bruce Beynnon, a professor of orthopaedics and rehabilitation at the University of Vermont College of Medicine. Beynnon has studied the correlation between a woman’s menstrual cycle and the risk of tearing the ACL. His results show there is a higher risk during the preovulatory phase than during the ovulatory phase. Other studies suggest this is caused by estrogen and estradiol.

Dr. Stephen Liu and associates, at the UCLA School of Medicine, made the discovery that there are estrogen receptors on the fibroblasts of the ACL. This suggests the sex hormone impacts the structure and composition of the ligament. During menstruation the levels of estradiol and estrogen fluctuate, and as another study by Dr. Xuhui Liu suggests, the more estradiol the less able the fibroblasts are to reproduce the collagen that makes up the ACL.

Beynnon, however, says it is hard to blame sex hormones as the cause of the increased risk in ACL tears. He says muscular control may also fluctuate with the menstrual cycle. “A lot of studies try to recreate the cycle phase that a woman goes through but that’s a very, very difficult thing to do,” he says, “When you start pointing to sex hormones I get very worried. There is definitely a difference in cycle phase injury rates, but we don’t know exactly what is causing that yet.”

In the end, no matter what the cause of an ACL tear, there is no quick fix. Depending on the degree of tear it can take an athlete from three months to a year to recover. However, there are ways a woman can help prevent the injury altogether.

“A lot of training has gone into technique, landing, cutting, and decelerating,” says Benoit, “They can seriously help reduce the number of injuries.”

So when it comes time to tie up the cleats and grab the soccer ball, women should seriously think about checking their technique. Something as simple as changing directions can mean the difference between scoring the winning goal and sitting on the bench for the rest of the season.

Co-produced by Tomek Sysak.