Female Athletes and ACL Injuries

Last week, I wrote about the experience that I had with working with a local high school girls basketball team and the conversation that took place with the head junior varsity coach and myself. I briefly explained the goals that the coach was seeking with working with me; however, I failed to talk about one other issue or topic that came up in the discussion.

Anterior cruciate ligament commonly known as the ACL.

Eight years ago 2.5 million high school girls and 145,000 college girls played some type of competitive sport. No longer are the days that girls are just participating in non-contact sports such as golf or tennis. They are now participating in more violent contact sports like football, basketball, boxing, roller demolition derby, field hockey, and lacrosse to name a few. Each year, females participation in sport has rising substantially in every major market or competitive arena from club sports all the way to collegiate competition. Even though, more females are signing up and participating in sports, more are watching on the sideline rather than playing on the field due to sustaining more injuries like ACL injuries.

ACL injuries are the most common injuries that most females will be faced with while participating in athletics. Each year, 1 out of 100 high school female athletes and 1 out of 10 college female athletes will go down with an ACL injury. The National Collegiate Athletic Association (more commonly known as the NCAA) reports that in a given year, approximately 2200 collegiate females are expected to go down with an ACL injury. These stats suggest that females are 4 to 8 times more likely to sustain this type of injury than males. Also research data shows that on average, an ACL reconstruction surgery costs a family $25,000 a year. In addition, the data from high school and college suggest that they spend over $100 million annually on reconstruction surgeries for females.


The question is why are females more susceptible to ACL injuries than males? And are there exercises that can be done to prevent them from being injured?

Many experts (myself included) think the reason why females are so susceptible is because of the anatomical differences that females have in comparison to males. In addition other common factors are muscle imbalances and variations in movement patterns.


Anatomical Differences

In the knee joint, an intercondylar notch lies between the femoral condyles. The ACL moves within this notch, connecting the femur (more commonly known has the thigh bone) and the tibia(more commonly known as the shin), providing stability to the knee. The ACL prevents the tibia from sliding forward and rotating inward. The majority of women have a small notch, therefore restricting ACL movement. When movement is restricted, the femoral condyles can easily pinch the ACL within the joint, especially during twisting or hyperextended movements. This ultimately can result in a tear or rupture.

The other difference lies in what is called the Q angle or the angle from the hips, femur, and tibia. The femur is affected because it meets the tibia at this angle and if a person has wider hips (which most females do in comparison to their male counterparts) it can have an affect on their ACL. The wider the hips, the larger the Q angle. At this greater angle, forces are concentrated on the ligament for stability each time the knee rotates. This increases the rotational forces on the ACL, raising the probability of a tear. A large Q angle also results in a more pronated foot (a foot that is turned outward), further stressing the knee.

Muscle Imbalance

The balance and relationship between how the quadriceps and hamstrings work together plays a crucial part to knee stability. Research shows that female athletes tend to have quadriceps to hamstrings muscle imbalances -- with the quadriceps as the dominating knee stability muscle. On the other hand, men have a better balance between quadriceps and hamstrings. They engage the hamstrings first when performing a movement, which actually decreases stress on the ACL. Therefore, the stability of the knee is more quadriceps-dominant (an ACL antagonist) in females and more hamstrings-dominant (an ACL agonist) in men.

So let's relate this concept to female involvement in sports. As stated earlier, females are now engaging in similar activities like their male counterparts which place the same demands on their bodies and knee structures with similar intensity (equal twisting and loading forces on the knee joint). Twisting, cutting and landing movements all stress the ACL to provide stability. As the quadriceps contract, additional stress is put on the ACL, increasing the risk of injury. So, if females or more quadriceps dominant, they are more susceptible in putting their ACL in danger of tearing because it is stressed more during the activity.

Variations in Movement Patterns
Contrary to what a lot of you reading this article may think, the majority of ACL injuries come from non-contact incidents on the field or court. These injuries are divided equally among the three main non-contact movements -- planting, cutting and straight-knee landings with hyper-extended knees. For unknown reasons, women tend to perform all these movements with straight legs. Straight-legged activities require the knees to absorb forces equal to four times an individual's body weight as well as encourage hyperextension of the knee joint. Hyperextending the knee is one of the major contributors to non-contact ACL injuries. Also, videos have show that women tend to perform planting, cutting and landing movements by turning the knees inward, further exaggerating the Q angle stress on the ACL and therefore increasing risk of an ACL rupture.

How can the athletic community assist females to decrease the risk of an ACL tear?

Obviously, anatomical characteristics that increase the risk of ACL rupture cannot be changed. As a result, the focus for prevention has been on teaching athletes the correct motor patterns to prevent excessive stress on the ACL through jump training (landing and propelling). Finally, because quadriceps-hamstring strength imbalance appears so important, athletes must also work to maintain flexibility of both of these muscle groups. As muscles are strengthened, flexibility can be lost unless athletes conscientiously cool down and stretch at the end of the workout..

The bottom line is:
• ACL injuries are a big problem
• ACL injuries are a bigger problem for females
• ACL injuries are preventable

Every serious female player (of ANY age) should:
Practice proprioceptive training (a good idea for competitive male soccer players as well)

Strengthen hamstrings by:
• Jump training and/or leg curls
• Avoid turning and landing with straight legs
• Cool down and stretch after exercise
These measures can help prevent serious injury and will almost certainly improve performance to boot. Sorry about the pun. I just couldn’t resist.
Reference:
Stephanie Vlach, M.S., is the Manager, Fitness Education for the Life Fitness Academy.

Personal Trainer in Charlotte, NC