Since Title IX went into effect in 1972, a large number of young women have had the opportunity to get involved in sports such as soccer, basketball, lacrosse, and many more.
But as more women embraced these sports, experts noticed that the number of knee injuries—in particular tears to the anterior cruciate ligament (ACL)—were spiking. Statistics revealed that women are 2 to 10 times more likely to experience an ACL injury than men.
Most ACL injuries occur not from the knee making contact with something, but rather as someone lands from a jump or abruptly changes direction while running, especially if it involves twisting or unstable movement.
Anatomy and biomechanics may raise risk
In their efforts to explain women’s vulnerability to ACL injuries, experts have pinpointed a few factors that they think contribute to it. However, there is no single or definitive known cause, and the evidence for some of these factors remains mixed:
The intercondylar notch, which is the groove at the bottom of the femur where it meets the knee, is larger in men than in women. It’s possible that this narrower notch in women restricts the movement of the ACL, especially during twisting movements.
In addition, women have wider hips than men, which can affect the alignment of the knee and leave women more prone to knees that move inward (knock-kneed). This movement puts stress on the ACL, especially during the added force of landing a jump or turning.
The way bodies move and react can differ by gender. For example, women’s knees tend to be more flexible than men’s, leaving them more prone to hyperextend the knee and put strain on surrounding muscles, tendons, and ligaments.
Also, women’s hip, buttock, and upper leg muscles are often not as strong as men’s. When they land from a jump or change direction, more force is exerted on the knee instead of being absorbed by the surrounding muscles.
Scientists don’t understand the mechanisms that would cause this, but some studies have found a link between women’s menstrual cycle and risk for ACL injuries. Women seem to be more susceptible to injury in the first part of their cycle, before ovulation.
Can ACL injuries be prevented?
Some aspects of the way women move while exercising and their muscle strength can be changed. A program known as neuromuscular training is a 6-week regimen designed to help women strengthen the knee joint and improve their balance and techniques for jumping and cutting.
However, in a recent review of studies to monitor the effectiveness of neuromuscular training, only a few showed a statistically significant decrease of injury risk—and in some cases it even raised risk.1
To prevent ACL injuries, the best advice for men and women alike is to strengthen the muscles that support the knee, particularly the quadriceps, hamstring, hip adductor, and gluteus muscles. It’s also important to keep these muscle groups supple by stretching after exercise.