Hip Weakness and Risk of Future ACL Injury

In prior posts we have documented the impact of ACL injuries on our athletes.  Unfortunately, these injuries are becoming more common especially among female athletes who are up to 8-10 times more likely to sustain an ACL injury compared to their male peers.  The risk factors behind these injuries have been described in previous posts, but it is important to note the majority of these tears are non contact in nature.  Most commonly, when an athlete in slowing down, changing direction, or changing speeds.  Within these sport movements we can examine the importance of technique, balance, coordination, and strength.  Without a foundational level of hip strength the thigh bone can move in extreme ranges of motion on the shin placing the ACL ligament at a greater risk of tearing.  

In our Physical Therapy practice we often see athletes who present with weakness in their outer hip musculature.  These muscles are crucial for all sport movements due to their ability to control movement at both the pelvis, hip, and knee.  Weakness or decreased contribution from these muscles in sports limits the ability of the body to actively decelerate the lower extremity.  Research has been debating the cause or correlation of hip weakness in ACL and knee injuries.  Does hip weakness lead to knee and ACL injury?

A recent study in the American Journal of Sports Medicine examined the predictive value of hip strength testing among athletes (Khayambashi et al. 2015).  500 athletes underwent pre season hip strength testing prior to competing in their respective sports.  ACL injuries were tracked and categorized as either contact or non contact in nature.  The researchers reported a 3% annual incidence in ACL injuries based on the 15 non contact injuries (6 female) sustained in season.  Of note, was the predictive nature of hip weakness on future ACL injury.  The injured athletes had significantly less hip abduction and external rotation strength as a percentage of their body weight compared to their non injured peers.    

This article adds to the existing evidence on the importance of pre season sports screening by Physical Therapists.  These screenings can help identify injury risk factors so at risk athletes are placed in appropriate injury prevention programs.  For more information contact your local Physical Therapist.