The Link Between ACL Injury and Core Stability in Female Athletes

The Link Between

Athletic injuries in young athletes are on the rise, causing concern among parents, coaches and athletes about the dangers of various sports. In response, researchers have been working to identify underlying problems that may predispose certain athletes to injury, and have uncovered significant findings about the characteristics that distinguish female athletes from their male counterparts.

One of the most frequently occurring and most severe athletic injuries is a rupture of the knee ACL, or anterior cruciate ligament. Not only is an ACL rupture painful and debilitating, but it can be career-ending for any athlete. Incidence of ACL rupture in female athletes is significantly higher than in male athletes in the same sports.

Knee Injury Contributing Factors

Many factors come into play that can lead to an ACL rupture. Individual anatomy, training status and lack of experience can predispose some athletes to injury. ACL injuries are more likely to occur in sports that demand rapid changes in direction and alterations in trunk position when stopping, landing and cutting.

Control of the trunk and core can have a profound effect on dynamic stability of the lower extremities. Poor trunk control puts extra torque on the knee, straining the ligaments that hold it in place. Because females have a broader pelvis than males, the angle from hip to knee is more pronounced, placing the lower extremities at greater risk for valgus collapse and injury.

Core stability is foundational to dynamic trunk control, facilitating the transfer of forces from the upper to lower extremities. A stable core plays a critical role in maintaining equilibrium, and regaining it when disrupted, by overriding the forces of gravity and momentum. When equilibrium is lost, those forces impact the lower extremities, especially the knee.

Research Comparing ACL Injuries in Male and Female Athletes

In a recent study, Zazulak et al. (2007) tested 137 male and 140 female college athletes for trunk displacement after force release, with the goal of identifying predictors of knee injury risk.

Trunk displacement was greater in athletes with knee, ligament, and ACL injuries than in uninjured athletes.

The research team found that:

  • Athletes with knee injuries had greater trunk displacement than uninjured athletes.
  • The strongest predictor of ACL injury was lateral trunk displacement.
  • Trunk displacement was a stronger indicator in female athletes
  • Low back pain history was a significant predictor in male athletes, but not female.

The takeaway message from this study and others like it is that factors predisposing athletes to knee injury can be identified in individual athletes, and measures can be taken to correct motor deficiencies to prevent and reduce the risk of knee injuries. Training interventions should incorporate core stability training, proprioception exercises, and disruption and correction of body sway to reduce the risk of ACL injuries in both male and female athletes.

Athletic Retraining at NYDNRehab

Measures of trunk displacement and other movement deficiencies require specialized equipment to detect and quantify abnormalities. At NYDNR, our expert team of sports medicine professionals uses cutting edge technology to detect and correct motor deficits. C.A.R.E.N, our computer assisted rehabilitation environment, maps an athlete’s movements by measuring forces during specific activities. The same technology can then be used to correct deficiencies through retraining.

Do not wait until you are injured to correct motor deficiencies in your sport. Contact NYDNR today for a complete analysis and retraining, to keep you in the game, injury-free.


Zazulak, Bohdanna T., et al. “Deficits in neuromuscular control of the trunk predict knee injury risk: prospective biomechanical-epidemiologic study.” The American journal of sports medicine 35.7 (2007): 1123-1130.


In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

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