Non-Contact ACL Injury

Anterior Cruciate Ligaments (ACL) sprains are the most common form of knee injury in America. The ACL injury incidence rates are higher in athletes than the general population. Non-contact ACL injuries are more common than contact-related ligamentous injuries. Females are up to eight (8) times more likely to injury their ACL than males.


Why are females at a greater risk of an ACL injury as compared to males?

There are numerous reasons why females are more prone to ACL injuries as compared to males. One of the physical therapists at Redlands Physical Therapy (Akef KI, Petrofsky J, Lohman E, et al. 2015) helped conduct a study to help determine why. One reason is related to hormonal changes during the menstrual cycle. These researchers concluded that changes in knee joint laxity during menstruation, in response to hormonal fluctuations, changes neuromuscular control at the knee during running.

In addition to hormonal fluctuations, there are other reasons why females are more prone to non-contact ACL sprains. These factors include:

  • An imbalance between the strength of the muscles on the front of the thighs (quadriceps) as compared to weaker muscles on the backside of the thighs (hamstrings).
  • A female athlete tends to decelerate while running using their quadriceps resulting in knee instability and sheer as compared to their male counterparts that typically use their hamstrings to slow down.
    During jumping, cutting, and deceleration activities, female athletes tend to allow their legs to buckle or collapse inwardly (“medial collapse”) due to motor control and strength impairments of the hip muscles (hip abductors and external rotators). This aberrant medial collapse movement causes both valgus and rotary stresses to the knee making the ACL more vulnerable. Other biomechanical errors more common to female athletes include landing on a straighter leg, weight-bearing primarily on one leg, and leaning laterally from the trunk.
  • Anatomical factors: Females tend to have several anatomical factors that place them at greater risk for an ACL injury as compared to males. These factors include: Females having wider pelvises, sharper intercondylar notch shape in the knee joints, and large angles (Q-angle) at the knees.

ACL Injury Prevention

Now that we know the cause, it is much easier to prescribe the cure. Physical therapists have successfully implemented ACL Injury Prevention Programs resulting in a reduction of sports-related ligamentous injuries. The focus of these programs includes correcting biomechanical faults, improving hip muscle motor control performance, and increasing core muscle strength. Finally, training athletes to become less reliant on their anterior thigh muscles (Quad dominance) and recruiting more hip muscle activation (Glut dominance) during sports activities is also encouraged. These programs typically occur prior to or at the beginning of the sports season. Females that participate in high demand sports (e.g., volleyball, soccer, skiing, etc) or exercise regularly (e.g., running, High-intensity Training (HIT)/Crossfit, etc) should be encouraged to participate in an injury reduction and neuromuscular training programs to reduce the risk of a knee injury. Rehabilitation following surgery can take as long as a year, while a injury prevention program takes only a few weeks. Education is therapeutic.

Akef KI, Petrofsky J, Lohman E, Daher N, Olfat M. 17β-Estradiol Induced Effects on Anterior Cruciate Ligament Laxness and Neuromuscular Activation Patterns in Female Runners. Journal of Women's Health. August 2015, 24(8): 670-680. doi:10.1089/jwh.2014.5184.

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Risk Factors

  • Pronated feet (low arches) can affect the alignment and tension on the Achilles tendon and calcaneus bone interface.
  • Pes Cavus (high arches) can also affect the alignment and tension on the Achilles tendon and calcaneus bone interface.
  • Being overweight can increase stressful forces.
  • Poor foot positioning during certain activities such as walking, running, or jumping can increase your child’s risk of developing this condition.
  • Being active is a risk factor. Children that play sports are exposed to activities that produce high-tension loads to your child’s heels, especially if the sport involves running and jumping on hard surfaces.
  • This disorder is more common in boys than girls.
  • Wearing stiff, hard shoes (e.g., soccer cleats).
  • There is a greater risk of acquiring this condition at the beginning of the sports season.

Thanks for Reading Our Blog!

Do you have any more questions about non-contact ACL injuries? How about any other musculoskeletal conditions? Use the form below or email us at and we'd be happy to help. If you'd like to schedule an evaluation just give us a call at 909-255-1694 or use our Online Patient Intake Form

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