National Collegiate Athletic Association

The NCAA News - News and Features

The NCAA News -- September 27, 1999

Sports Sciences Education Newsletter

ACL group presents findings, risk factors for female student-athletes

In June 1999, an Anterior Cruciate Ligament Consensus Conference was organized in Hunt Valley, Maryland, to evaluate prevention strategies for non-contact ACL injuries in female athletes. Twenty-one participants representing orthopaedic surgeons, biomechanists, and athletic trainers attended the conference funded by the American Orthopaedic Society of Sports Medicine, NATA Research and Education Foundation, the NCAA Sports Sciences Division, and the Orthopaedic Research and Education Foundation.

This conference used the Wojtys' scheme of dividing risk factors into sub-categories of environmental, anatomic, hormonal, and biomechanical risk factors. Participants, after carefully reviewing available data in each of these risk categories, formulated the following consensus statements.

Regarding risk factors for non-contact ACL injuries:

Environmental risk factors

  • There is no evidence that functional knee braces prevent ACL injury.

  • Increase shoe/surface coefficient of friction may improve performance but also may increase the risk of injury to the ACL. Because it is modifiable, shoe/surface interface merits further investigation.

    Anatomic risk factors

  • Although there is much literature on the role of the femoral notch size in ACL injuries, no consensus on the notch's role in ACL injury can be reached at this time because of the difficulty in achieving valid and internally and externally reliable measurements.

  • At present, there is insufficient data on the ACL size (absolute or proportional) to support that ligament size is related to risk of injury.

  • At present, there are insufficient data to relate lower extremity anatomic alignment to ACL injuries. Further studies are needed to investigate possible relationships between anatomic alignment and injury.

    Hormonal risk factors

  • There is no consensus in the scientific community that sex specific hormones play a role in the increase of ACL injury in female athletes, but there is sufficient evidence to warrant continued investigation of hormonal influences on ACL injury.

  • At present, hormonal intervention for ACL injury prevention is not justifiable.

  • For ACL injury prevention in females, modification of activity or restriction from sport at any time during their menstrual cycle is not recommended.

    Biomechanical risk factors

  • The knee is one part of the kinetic chain and anatomic sights other than the knee including the trunk, hip, and ankle may contribute to ACL injuries.

  • Strong quadriceps activation during eccentric contraction is a major factor in injury to the ACL.

  • Common biomechanical factors involved with many (not all) injuries during landing or changing directions include impact on flat foot rather than on the toes, awkward dynamic body movement, and perturbation prior to injury.

  • The common at risk situations for non-contact ACL injuries appear to be decelerating, cutting or changing directions, and landing from a jump.

  • Neuromuscular factors are significant in the increase risk of ACL injuries in females and neuromuscular factors appear to be the most important reason for the differing ACL injury rates between males and females.

    Regarding prevention strategies

  • Training and conditioning programs for male and female athletes in the same sport may need to be different.

  • Specific training programs which enhance body control reduce ACL injury rates in female athletes and may increase athletic performance.

  • There is a need to identify sports specific to risk motions and positions and encourage athletes to avoid these at risk situations when possible as well as to identify strategies for activating protective neuromuscular responses when at risk situations are encountered.

    With regards to future directions for research

  • There is a need to improve public and participant awareness of ACL injury including the possibilities for injury prevention.

  • There is a need to continue to define the specific neuromuscular, proprioceptive, and motor control factors associated with ACL injury.

  • However, until specific predictive and protective factors are definitively determined, training and prevention strategies should continue to be implemented, assessed and approved.