Non-Contact ACL Injuries in Female Athletes: Where are we now?

Scientific knowledge expands daily. This article was published in 2008. THEREFORE…the information you are about to read MAY contain concepts that are obsolete…READER DISCRETION IS ADVISED!

The following is a summary of the IOC current concepts statement published in the British Journal of Sports Medicine. Contained within this summary are the general principles that were established based on decades of research pertaining to ACL injuries in female athletes.  Since the amount of potential factors associated with injury are plentiful, this review is limited to only those concepts with conclusive evidence.

Epidemiology

• As a whole, ACL injuries most commonly result from non-contact mechanisms
• Although the rates of ACL injury in men and women are similar in professional sports, younger female athletes are at higher risk (than aged- and sport-matched males)
• Along with men’s spring football, women’s gymnastics, soccer, and basketball have the highest injury rates per 1000/athlete exposures.
• Consistent with most sports, injury rates are higher during competition

Risk Factors

• There is an association between intercondylar notch width and risk of ACL injury. Females generally have smaller notches than males and therefore, likely a smaller ACL. It has been suggested that these ACLs may have lower linear stiffness, fail earlier in elongation, absorb less energy, and fail with lower loads.
• The relationships among the presence of sex hormones within the ACL and oral contraceptives with ACL injury risk are still inconclusive.
• Women appear to be at greater risk of ACL injury during the pre-ovulatory phase.

Mechanism of Non-Contact Injury

• Injuries most often occur when landing from a jump, cutting, or deceleration.
• Kinematic analyses have revealed that women land with less knee flexion than men. Women also maintain higher knee extension and valgus during stance phases of running and cutting. Finally, women also display higher quadriceps EMG activity during max loading. Therefore, a straighter knee and higher quadriceps activation likely contribute to the injury mechanism. Other components include anterior translation, dynamic valgus in near extension, increased trunk motion, and a high load placed on the leg or foot that is away from the body’s COM.

Evaluation

• Key components of diagnosis include: sudden knee pain during high intensity activity, inability to resume play, “popping” sensation, haemarthrosis.
• The course of ACL injury classifies the injured into copers, adaptors, and non-copers.
• ACL reconstruction does not warrant surgical management of the injured MCL.
• The meniscus is associated in approximately 50% of ACL injuries. Note: Mike Reinold recently posted an excellent blog (by D. Lorenz) on meniscal testing here.
• A thorough examination searches for articular cartilage, ligamentous, and bony/bone marrow lesions.
• The pivot shift test is best for ruling in ACL injury. The Lachman test is best for ruling out ACL injury. (It is also the most accurate).
• Patient-administered questionnaires should be used as an outcome measure and quantified scores should be kept separate from categorical variables (good/excellent).
• While the incidence of injury in girls increases at puberty, there is a potential risk of growth disturbances with prepubescent operative management.

Rehabilitation

• Although the restoration of full knee extension is important in initial stages of rehab, ROM should be compared with the unaffected knee to determine normal ranges (hyperextension may be the norm in some patients).
• OKC training should be introduced and progressed cautiously, commencing between 90 and 40 degrees.
• CKC exercises recommended at the commencement of rehab. Early weight bearing and mobilzation are safe.
• A minimum of 3-4 functional performance tests should be used for evaluation.
• Return to play should be goal-based (not time-based)

Prevention

• Most prevention programs utilize neuromuscular and proprioceptive training to alter the dynamic loads placed on the tibiofemoral joint
• Henning was the pioneer in neuromuscular training for ACL injury prevention (just thought I’d add that in, dude deserves his props!)
• Program intervention generally takes a minimum of 4-8 weeks in order to impart its desired effect.
• Programs should be implemented as early as possible (age) and those that use minimal equipment are generally more successful
• In jumping sports, proper landing involves softly landing on the forefoot, rolling back to the rearfoot, two-feet landing, and knee and hip flexion engagement.
• In cutting sports, dynamic valgus should be avoided as the “knee over toe” position should be emphasized.
• Programs should be incorporated as a regular warm-up, should also include strength, power, plyometric, and agility exercises
• The drop vertical jump test is a good way to identify those at risk.

​There you have it. My generalized summary of the IOC current concepts statement. Since published research on ACL injuries literally come out daily, please be reminded that some of the above concepts may have been updated.