Current Topics in Women's Sports Medicine

Evaluation and Treatment of the Female Athlete

Miho J. Tanaka, MD

Disclosures

Curr Orthop Pract. 2019;30(1):11-15. 

In This Article

Anterior Cruciate Ligament (ACL) Injuries and Prevention

ACL injuries are four to eight times more common in female athletes than male athletes.[3–5] With the increasing number of female athletes, the number of ACL reconstructions performed in women has continued to rise at a rate greater than in men.[6,7] Multiple factors have been associated with this increased risk. Hormonal influences have been studied in their relationship to ACL injuries in women, yet the significance of this influence is unclear. Several studies have noted a relationship between the timing of ACL injuries in women and preovulatory phase of the menstrual cycle, indicating a potential hormonal influence.[8,9] Relaxin is one hormone that has been studied in its relationship to ACL tears. Dragoo et al.[10] found that female athletes with serum concentrations of relaxin greater than 6.0 pg/mL have a four-fold increased risk of ACL injury. An in-vitro study has shown that relaxin appears to influence the structural integrity of the ACL by altering collagen expression and matrix metalloproteinases,[11] but the exact role of hormonal factors on ACL injury is still unknown. Currently, no current clinical data support that hormones should play a primary role in injury management or prevention in female athletes.[12]

The majority of ACL injuries occur without contact, during pivoting or landing motions. The most modifiable risk factor contributing to the increased risk of noncontact ACL injury in female athletes is a deficiency in neuromuscular control.[13,14] Dynamic factors, such as increased valgus moment at the knee and asymmetry during landing activities, have been shown to be associated with increased risk of ACL injuries, and these findings are more prevalent in female athletes.[15,16] In a recent biomechanical study based on motion analysis, female athletes demonstrated significantly increased knee abduction moments during drop landing when loaded in similar conditions to male athletes.[17] Female athletes also have been shown have greater hip adduction moment and internal rotation when compared to male athletes, as well as decreased relative hamstring activation during such landing drills and decreased trunk stability.[13,18,19]

ACL injury prevention programs have been designed to address these specific neuromuscular deficits through strengthening, balance, and plyometric training exercises. Webster and Hewitt[20] recently performed a summary metaanalysis on the effectiveness of ACL injury prevention programs and reported an overall 50% risk reduction in all athletes, specifically reporting a 67% risk reduction in noncontact ACL injuries in female athletes. Current findings support the role of injury prevention exercises in a tailored and individualized fashion. Meyer et al.[21] identified that the injury prevention programs are most effective in age groups under 18 yr of age. Prevention programs that target strengthening, proximal (trunk and hip) control exercises, as well as those that incorporate multiple types of interventions, have been shown to be the most effective in reducing risk of injury.[22]

In terms of morphology and anatomical risk factors, the widths of the femoral notch and tibial slope have been identified as independent risk factors for ACL injury in women. In a study of 88 noncontact ACL injuries, Sturnick et al.,[23] using a best-fit model for female athletes, calculated, that each millimeter decrease in notch width was associated with a 50% increase in the risk of ACL injury, and a 1 degree increase in posterior-inferior slope of the lateral tibia was associated with a 32% risk. Currently, however, no intraoperative differences exist in the treatment of male and female athletes with ACL injuries.

Although outcomes after ACL reconstruction are not frequently reported by gender, a recent study from the Swedish registry showed that at 1 yr, male athletes had a favorable odds ratio of returning to sports by 2.58 when compared to female athletes.[24] A 20-year follow-up of patellar tendon autograft ACL reconstruction showed that women had lower rates of graft tears than men (2% vs. 18%, P=0.01), but poorer subjective IKDC scores (83 vs. 90, P=0.03), more activity-related pain (57% vs. 20%, P=0.02) and were less likely to participate in strenuous activities (35% vs. 66%, P=0.009).[25] Webster and Feller[26] recently reported in a large series that athletes had three times the odds of returning to sports if they had IKDC scores of 95 or higher. In their study of 1440 athletes, female athletes had lower rates of return to play within 1 yr than their male counterparts in ages younger than 25 and 26 to 35 yr age groups (39% vs. 52% and 18% vs. 37%, respectively). No differences were seen after 36 yr of age.

While overall rates of ACL reinjury are lower in female athletes, in soccer specifically, female players have been estimated to have a 2.8 times higher rate ratio of recurrent injury than male players.[27] A study of female soccer players after ACL reconstruction found that they had a 15% rate of recurrence and a 19% rate of contralateral injury.[28] Contralateral ACL injury risk has been reported to be 6.21 times greater in women than men and may be an area of further targeting for injury prevention in future studies.[29]

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