As the number of female athletes has grown and the level of competition has increased in female sports, a disturbing trend has become clear. Female athletes are highly susceptible to injuries of the anterior cruciate ligament (ACL) as well as other stabilizing ligaments of the knee. Various studies have found injuries rates in females to be 4-7 times higher than in similar aged males. Even more concerning is that 62% of these injuries were non-contact injuries, meaning the player was not involved in a collision with another player when the injury occurred. This trend became so blatant that researchers in the medical profession began to take note and started a crusade to find the contributing factors that were setting our female athletes up for such injuries. The findings from these research studies have been illuminating and have provided members in the therapeutic fields useful information for understanding the contributing factors and thereby creating means to analyze and attend to the modifiable factors that young athletes display. The second wave of research in this area has focused on prevention programs and the effects of providing young athletes with preventative programs to counteract the physical factors that predispose girls to ACL injuries. Almost all of the programs in place have certain basic concepts in common and almost all studies have shown 2-4 fold decreases in the number of ACL injuries compared to control groups. This is good news for athletes and coaches hoping to play to the highest level possible. The goal for us at Walton Physical Therapy and indeed the therapy community as a whole is to now disseminate this information to coaches and players so they may incorporate these strategies into their practices and benefit from the efforts of researchers and medical practitioners worldwide.

The studies investigating ACL tears in women have addressed many factors and found that there are many factors that may contribute to the risk of ACL injury. Some of the contributing factors are not controllable including hormonal changes, congenital narrowing of the groove the ACL must pass through in the knee and familial predisposition. Focusing on physical factors that are not modifiable tends to muddy the waters and dilute the message that athletes need to receive, namely, what can they do to correct modifiable factors to decrease their level of risk for ACL injury. Many of the contributing factors for ACL injury involve the physical alignment of the lower extremity and more specifically how the lower extremity moves dynamically in landing, cutting and decelerating maneuvers. The patterns of alignment and movements at the various levels of the lower extremity are as follows:

Foot: Females with flat feet (excessive pronation) are predisposed to ACL injury because as the arch drops, the lower leg bone will also fall inward collapsing the knee towards midline. This position of the knee tensions the ACL and is likely to tear the ligament if these forces dropping the knee inwards are not controlled by the muscles of the hip and knee. Controlling the speed and amount of arch drop can take some of the pressure off the muscles of the hip and knee with respect to keeping the knee from going into this dangerous position of no return a position where the muscles can no longer protect the ligaments of the knee from injury.

Knee: The most dangerous position for the knee is the knock-kneed position (knee valgus). As described above the foot position can contribute to this alignment as well as the natural hip position. When girls have a tendency towards this alignment naturally, they must be sure that the muscles controlling motion into further valgus positioning are strong and placed in a position they can be used maximally while playing. The tendency for many girls is to play very upright compared to their male counterparts. The muscles of the knee provide most of the stability of the joint with the knee in 20-30 degrees of flexion (bending). A female athlete can be very strong, but if she gets fatigued and starts playing with less flexion of the knees, her muscles will not be in a good position to control the forces going through the knee and her ligaments will have to take the brunt of those forces. Another daily activity that can limit the stability in the knee is when girls stand with the knee hyperextended (recurvatum). This stretches the capsule and the stabilizing ligaments of the knee and can predispose girls to dynamic injury.

Hip: ACL injuries occur when girls hips turn inward and the upper leg drops towards the midline of the body. This is tensions the ACL and lengthens the muscles on the outside of the hip that normally control the inward rotation of the knee. If the normal alignment for a player is internally rotated hips (Knock-kneed) she will be more likely to tear her ACL if she does learn to control her natural tendency towards allowing the knee to fall inwards. Women generally have a wider pelvis than men which increases the likelihood of this alignment and necessitates more strengthening to control the increase inwardly directed forces through the knee. Several daily positions that can lengthen the stabilizing muscles on the outside of the hip should be avoided, including lying on your side with the upper leg crossing over the bottom (use a pillow between the knees), crossing the legs while sitting and standing with your weight shifted to the outside of the foot.

In addition to these specific alignment tendencies, the form with which girls land from jumps and move when cutting can predispose them to injuries. Female athletes tend to bring their knees together towards midline when landing. This movement strategy may be engrained by spending time in the above-mentioned positions throughout the day. When it comes to moving, the joints and muscles often choose the positions they are used to. Females also tend to play with less bending in the hips and knees. This strategy probably helps to conserve energy because the muscles are not having to work as much, but it also puts the muscles in a position of mechanical disadvantage if they are needed to control the knee from dropping into the position of no return.

Controlling these modifiable, predisposing factors can have a direct influence on the likelihood of suffering an ACL injury. There are many well-researched programs available for team warm-ups that address these issues and can decrease the incidence of injuries for a team when incorporated as a component of regular training. The Santa Monica ACL Injury Prevention Program (PEP program) is an excellent program to address the contributing alignment and movement tendencies described above. If you are a coach, you can download the warm-up and incorporate it into your training regimen. Reviewing the program with a physical therapist may enhance the utility of the program as certain instructions to the players can improve the quality of performance. Another excellent resource for information and suggestions on ACL prevention is the Nike-based SPARQ program (sparqtraining.com).

For further information and personalized and/or team training please contact us at Walton Physical Therapy. We provide individual testing to determine physical limitations and offer personalized and team warm-ups and training programs to address the factors limiting athletic performance and predisposing athletes to injury.

ACL Prevention

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