Sex-Based Differences in Common Sports Injuries

Cordelia W. Carter, MD; Mary Lloyd Ireland, MD; Anthony E. Johnson, MD; William N. Levine, MD; Scott Martin, MD; Asheesh Bedi, MD; Elizabeth G. Matzkin, MD

Disclosures

J Am Acad Orthop Surg. 2018;26(13):447-454. 

In This Article

Anterior Cruciate Ligament Injury

Abundant data exist demonstrating that female athletes are particularly vulnerable to ACL rupture; the incidence of noncontact ACL injuries is two to eight times higher in females compared with males participating in basketball, soccer, team handball, netball, and alpine skiing.[16] According to survey data obtained from the US National Collegiate Athletic Association, females who participate in collegiate basketball have more than a threefold increased risk of sustaining an ACL injury than their male counterparts; female collegiate soccer players have a similarly high relative risk of noncontact ACL injury (relative risk = 2.75).[16] Therefore, given the higher rate of sports participation among males, the absolute number of ACL injuries remains higher for this group than for female athletes.

Risk factors for ACL injuries have been classified as nonmodifiable (eg, anatomic, structural, hormonal) or modifiable (eg, neuromuscular, biomechanical). An expert consensus is that modifiable factors may be more important in explaining the higher incidence of noncontact ACL injuries among female athletes.[17]

One primary modifiable risk factor for ACL injury that has been shown to differ between the sexes is the landing pattern.[18] Females tend to exhibit valgus collapse and increased abduction moments at the knee, both of which are predictive of ACL injury. In addition, when performing a single mini-squat, females tend to exhibit an anteriorly rotated pelvis, contralateral pelvic drop, hip internal rotation and adduction, knee valgus, tibia external rotation, and foot pronation[19] (Table 1). Similarities can be observed between the single mini-squat and the mechanism of noncontact ACL injury, which seem to set up the female athlete for ACL rupture.

Nonmodifiable risk factors for ACL injury also exist. For example, smaller notch dimensions may predispose individuals to ACL injury. However, a sex-based difference does not seem to exist in this respect.[20] Other studies that evaluate the role of bony architecture in ACL injury risk have reported that a shallow medial tibial plateau and steep tibial slopes are risk factors for ACL injury; these anatomic differences have not been shown to be sex dependent.[21] Sex-based differences in the osseous anatomy of the knee have been reported, including differences in femoral condyle shape, hip version, and the length of the femur compared with the pelvic width. To date, however, no causal relationship between these factors and ACL injury has been proven.

Another nonmodifiable risk factor that has been theorized to correlate with ACL injury is the changing levels of circulating sex hormones throughout the female menstrual cycle; however, data are insufficient to make any conclusive statement regarding menstrual cycle, laxity, and the risk of ACL injuries in females.[22]

Interestingly, Posthumus et al[23] demonstrated that genetics likely plays a role in ACL injury risk; the COL5A1 gene (which codes for alpha chains of collagen) is associated with an increased risk of ACL injury in females.

In terms of treatment and outcomes for athletes with ACL injury, information on sex-based differences is lacking. Prospective studies investigating whether sex affects a surgeon's choice of graft for ACL reconstruction are needed. Similarly, little information is available on whether and how sex affects postoperative rehabilitation and return-to-play decisions. Brophy et al[24] found that in soccer players followed for 7 years after ACL reconstruction, females were more likely than males to require further ACL surgery and less likely to return to play. A 2014 meta-analysis of 13 studies demonstrated no difference in graft failure, contralateral ACL rupture, or patient-reported outcomes as a function of the patient's sex.[25] However, the authors of this meta-analysis concluded that more high-quality studies are needed.

The incidence of ACL injury remains markedly higher in female athletes than in male athletes, even after controlling for sport. In addition, sex-based differences have been identified for both modifiable and nonmodifiable risk factors for ACL injury. However, sex-based differences in treatment and outcomes of this injury have not, as yet, been clearly delineated. More research studies on potential sex-based differences in risk factors, treatment, and outcomes for athletes with ACL injuries are needed.

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