Dynamic Genu Valgus in the Female Athlete
According to a study by Arendt (1995), females are between two to eight times more likely to injure their ACL than their male counterpart in similar sporting events. Typically the injury occurs in activities involving a lot of quick cutting motions, jumping motions and rapid slowing or decelerating movements.
In a study publisged in the British Journal of Sports Medicine (2008), the International Olympic Committee invited a multidisciplinary group of ACL expert clinicians and scientists to review the reasons for the higher prevelance in female athletes. The risk factors noted included:
– being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase
– having decreased intercondylar notch width on plain radiography
– developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing – termed “dynamic Genu Valgus”
Of the three risk factors listed, as practitioners/trainers, it is the last one that we are able to work on.
The video demonstrates a large increased knee abduction moment (Dynamic Genu Valgus) upon landing. The patient is a 14 year old soccer player was referred to us after already having torn her left ACL and had reconstructive surgery 5 months prior to the date the video was taken. The rehabilitation program that was undertaken post surgery was obviously insufficient in coordinating the neuromuscular system to control for coronal plane forces. As such, this particular patient is at high risk to re-injury the repair.
Studies have concluded that the incidence of ACL injuries can be reduced through neuromuscular training (Roniger, L. R., 2007). With this type of training, females have been shown to reduce valgus moments when landing (Foster, J. B., 2007). Moreover, as a result of the training, female athletes can incorporate more muscular control and experience less ligament dependence during movements such as cutting, landing, jumping and rapid deceleration.
In order to correct ligament dominance in female athletes, a neuromuscular training program must be designed to teach the athlete to control dynamic knee motion in the coronal (abduction and valgus) plane. The first concept that the athlete and coach must be taught is that the knee is a single-plane hinge, not a ball-and-socket joint. Re-education of the female neuromuscular system away from multiplanar motion of the knee to dynamic control of knee motion in the sagittal plane only is achieved through a progression of single, then multiplanar, exercises. These programs’s attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasize proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the “knee over toe position” when cutting.
An example would be training the athlete with deep knee flexion jumps. This teaches her to increase the amount of knee flexion and decrease the amount of time in the more dangerous straight-legged position. At the same time, the athlete can reprogram peak flexor/extensor firing patterns, increasing co-firing and quadriceps firing in deep flexion for greater protection of the ACL.
We tend to also emphasize exercises that promote proper coordination in the entire lateral kinetic chain. For example, Gluteal function must be corrected in order to prevent excessive pelvic tilting on landing/cutting that can also contribute to excessive valgus motion.
Finally, core instability—as evidenced by increased trunk motion—must be corrected in those female athletes that demonstrate instability. These include progressive neuromuscular training techniques that target the balanced and synchronized turn-on of the dynamic stabilizing musculature of the trunk, pelvis, and hip. Unstable surfaces, single-leg balancing, and perturbation training should be used.