The slightest mention of an ACL tear strikes fear in the hearts of even the toughest athletes, and for a good reason. The career ending injury occurs in 1 of every 3,000 individuals each year, and it has been reported to occur upwards of 9 times more often in women than men. We have all heard that ACL injuries are more common in females than males, but why exactly is that the case?
Not surprisingly, female anatomy has been called into question as the culprit of increased rates of knee injuries. Women have a wider pelvis, which causes the femur to descend at a much sharper angle inwardly than men. Medically, the angle of the femur is called the “Q- angle”, and a greater Q-angle can give what is often known as a knock-knee appearance. This alignment of the female femur puts more pressure on the inside part of the knee, which is thought to contribute to ACL tears.
Besides the width of the pelvis, another contributing factor is an imbalance in the strength of female leg muscles. Women tend to have stronger quadriceps muscles (located in the front of the thigh), and relatively weaker hamstring muscles (located in the back of the thigh). This imbalance causes additional stress to be placed on the ACL, leading to an increased risk of tear.
The construct of the ACL itself may be a cause of increased tears in women. Females generally have smaller ligaments compared to men, which makes even the smallest tears detrimental to their physicality. On top of that, women have more lax ligaments, meaning they have more give. This increased laxity allows for more joint mobility, which predisposes women to ACL tears.
More recently the contribution of neuromuscular control and biomechanics as predisposing factors has been studied. To explain, researchers have looked at the way females jump, cut, land, and rotate during sporting events. Compared to men it was found that women tend to bend their knees less upon landing, meaning they allow their joints to take on most of the force of impact. Women also buckle their knees inward when landing and making cuts, which puts even more stress on the inside part of their knees. Furthermore, women’s feet flatten out upon impact which adds to the mounting stress on their ACLs.
How to prevent ACL tears?
Females should keep in mind the ideal athletic stance during physical activity. This includes having bent knees, their butts down, and their weight on the balls of their feet. Exercise programs targeted at strengthening the hamstrings, reducing the impact of landing from jumps, and proper cutting techniques are absolutely recommended.