We treat a fair number of patients with Anterior Cruciate Ligament (ACL) injuries at our clinics. Over the last decade, the number of young female athletes with ACL injuries has increased. In fact, female athletes are four-to-ten times more likely to sustain an ACL injury than their male counterparts. It is estimated that in the United States, over 50,000 female high school athletes per year experience an ACL injury.
The following are some of the theories that provide an explanation for the high frequency of ACL injuries in young females:
1. Anatomical differences – Women have a narrower intercondylar notch in their femur where the ACL ligament runs. This leads to a greater likelihood of pinching or shearing the ligament in this space. Women also have a wider pelvis than men, and that creates a larger Q angle (the vertical angle formed where femur meets the tibia in the knee). Due to this angle, the forces that go through the knee via the ACL are concentrated, thus increasing the risk of ACL tears in females.
2. Hormonal changes – Female hormones such as estrogen and relaxin contribute to better flexibility but also cause the ligaments, tendons, and muscles to be looser and less stabile. As a result, the female ACL must work even harder to provide stability and to absorb the stresses and forces directed through it which increases risk for rupture. It has also been shown recently that women are more likely to rupture an ACL during specific points in their menstrual cycles due to hormone fluctuations.
3. Muscular imbalance – Women tend to have a muscular imbalance between the quadriceps (the large muscle in the front of the leg) and the hamstrings (the large muscle in the back of the leg). Women tend to use their quadriceps muscles when decelerating, which causes greater forces to be exerted through the knee and ACL. In contrast, men tend to use their hamstrings muscles when decelerating, which better protects the ACL. Women also tend to have less muscle strength in proportion to bone size, while men’s muscles surrounding the knee are stronger and provide better stability. These factors cause women to rely less on their muscles and more on their ACL’s, making them prone to injury.
Although we recommend all athletes reduce their risk for ACL injuries by performing training drills including balance, power, and agility exercises, female athletes may benefit the most based on the above factors. Plyometric exercises also improve neuromuscular conditioning and muscular reactions that ultimately decrease the risk of ACL injury. Indeed, research shows that many of the non-contact ACL injuries may have been preventable with proper neuromuscular training.
Freedom Physical Therapy Services offers personalized physical therapy and an ACL injury prevention class emphasizing stability, strength and neuromuscular training. Drills, exercise guidance and education are designed to allow for athletes to continue on their own following class. If you are interested in signing up for this class, please contact our Fox Point location at (414) 352-2082.
Molly Rittberg, DPT