Where Does it Hurt? ACL

It is a known fact that women have a much higher incidence of ACL injuries then their male counterparts.  Depending on the particular sport, sometimes upwards of 10 times a greater risk can be reported.  This is statistically significant enough to study the physiologic reasons of the epidemic with the intent of educating and pre-habilitating girls who are or are becoming active in sports.  This article is meant to cultivate awareness about the problem.  

The ACL or anterior cruciate ligament is one of two ligaments inside the knee joint.  The other ligament is the PCL or posterior cruciate ligament.  The ACL’s main role is to prevent the tibia from sliding too far anteriorly(forward) underneath the femur.  It also prevents over-straightening and over-rotation of the femur on the tibia.  An ACL injury occurs when the knee is sharply twisted and pushed beyond its normal range of motion.  When the foot is planted with the knee bent and a change in direction is emphasized, the ACL can be compromised.  Upon performing this “cutting” motion, many patients report hearing a “pop” when the ACL tears.  Typically there is immediate swelling and quite a bit of pain.  Often the patient will describe an uneasy, unstable or buckling sensation within the knee.  

There are external and internal risk factors of ACL injury.  External risks include competition/practice intensity, footwear, playing surfaces, protective equipment, and the weather.  These exist for both genders so we will remove them from the equation.  We are more interested in the internal risk factors that predispose females to a greater potential for injury.  Internal risk factors include abnormal posture and lower extremity alignment.  This is when you will hear practitioners speak about the “Q” angle.  Specific anatomical differences between the genders including the intercondylar notch size, ACL geometry and ACL size have also proven to be a predetermining factor for increased risk of injury for females.  Therapy and other conservative measures will have essentially no effect on these factors so we will consider them constants among females.  

In the British Journal of Sports Medicine, April 14, 2008, an article pertaining to ACL injuries in females reported that the likelihood of incurring an ACL injury does not remain constant during the menstrual cycle, with a significantly greater risk during the pre-ovulatory phase than during the post-ovulatory phase.  In one study of recreational Alpine Skiers, 74% of the women with ACL injuries were in the pre-ovulatory phase of their menstrual cycle and 26% were in the post-ovulatory phase.  Other studies supported this and more investigation is currently taking place to uncover the relationship between hormone levels and ACL integrity.  

All of the previous information may be very interesting and may lead to advances in the prevention of ACL injuries in the future, but we as therapists and practitioners are more interested in what can be done now with knowledge and abilities.  The kinematic research has proven that females typically have a “quadriceps” dominant neurological firing sequence as opposed to males who have much greater hamstring recruitment.  Successful programs share a number of common threads.  Most include one or more of the following: traditional stretching, strengthening, awareness of high-risk positions, technique modification, aerobic conditioning, sport-specific agility, proprioceptive and balance training, and plyometrics.  

One study in particular by Dr. Henning proved to be very encouraging.  Dr. Henning implemented a prevention study in two NCAA Division I basketball programs over the course of 8 years.  He proposed that the increased rate of ACL injury in female athletes was primarily functional and was related to knee position and muscle action during dynamic movement.  He proposed that the athletes cut, land and decelerate with the knee and hip in flexion.  In addition, he proposed a rounded cut maneuver instead of a sharp or more acute angle during the cut cycle.  He also proposed a three-step quick stop instead of a one-step stop.  With this technique modification, the intervention group had an 89% reduction in the rate of occurrences of ACL injuries.  This served as a basis for many prevention programs currently in use around the world today.  

With simple observation, a well trained practitioner, coach, or athletic trainer can easily determine if a patient is susceptible to ACL injury.