Review Article Sex-basedDifferencesinCommon Sports Injuries · to be diagnosed with the syndrome. Determining the true prevalence of FAT is difficult, especially as the def-inition

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Review Article

Sex-based Differences in CommonSports Injuries

Abstract

Thepatient’s sex plays an important role in mediating the risk for, andexperience of, disease. Injuries of the musculoskeletal system are noexception to this phenomenon. Increasing evidence shows that theincidence, clinical presentation, and treatment outcomes for maleand female patients with common sports injuries may vary widely.Stress fracture, which is associated with the female athlete triad, is asports injury with known sex-based differences. Other commonsports-related injuries may also have distinct sex-based differences.Understanding these differences is important to optimize eachpatient’s musculoskeletal care.

Atthe end of the 20th century, theNational Institutes of Health

(NIH) implemented a series of policychanges that substantially increasedthe proportion of females participat-ing in NIH-funded clinical trials.1

These changes have had the desiredresult of improving our understand-ing of sex-based differences that existin clinical medicine. More recently,the NIH has focused on ensuringthat preclinical trials include bothmale and female cells and animals inthe laboratory.1

The musculoskeletal system is rifewith sexual dimorphism. One exam-ple is that males have greater bonemass, greatermusclemass, andgreaterlean mass than do females. Varioussex-based differences in injuries anddiseases of the musculoskeletal systemhave been described, including differ-ences in osteoporotic hip fracturesand osteoarthritis of the knee and thecarpometacarpal joint of the thumb.2

Most of the existing data regardingsex-based differences in the incidenceof sports injuries are from thepediatricliterature. One recent epidemiologicstudy of sports-related injuries (SRIs)in Canadian children and adolescents

reported that males are more fre-quently injured during sports partici-pation than females are. Malescomprised 71% of SRIs in this study,reporting higher injury rates in 11 ofthe 13 sports investigated.3 A morerecent study of children aged 5 to 17years in the United States describedthe type, location, and chronicity ofSRIs as a function of sex.4 Theauthors noted that females are morelikely than males to have overuseinjuries; for example, females arethree times more likely than males todevelop patellofemoral knee pain.Males are markedly more likely thanfemales to sustain acute, traumaticinjuries such as sports-relatedfractures.4

Mounting evidence exists support-ing the concept that the incidence,clinical presentation, and functionaloutcomes formale and female patientswith sports injuries may profoundlydiffer. By improving our understand-ing of these sex-based differences,orthopaedic surgeons may be betterequipped to care for patients withcommon sports injuries and improvetreatment outcomes. For example, theintraoperative choice of an anterior

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

From the Department of OrthopaedicSurgery, Yale University, New Haven,CT (Dr. Carter), the Department ofOrthopaedic Surgery, University ofKentucky, Lexington, KY(Dr. Ireland), the Department ofOrthopaedic Surgery, San AntonioMilitary Medical Center, San Antonio,TX (Dr. Johnson), the Department ofOrthopaedic Surgery, ColumbiaUniversity, New York, NY (Dr. Levine),the Department of OrthopaedicSurgery, the Brigham & Women’sHospital, Boston, MA (Dr. Martin), theDepartment of Orthopaedic Surgery,the University of Michigan, Ann Arbor,MI (Dr. Bedi), and the Department ofOrthopaedic Surgery, HarvardMedical School, Boston, MA(Dr. Matzkin).

J Am Acad Orthop Surg 2018;26:447-454

DOI: 10.5435/JAAOS-D-16-00607

Copyright 2018 by the AmericanAcademy of Orthopaedic Surgeons.

July 1, 2018, Vol 26, No 13 447

Copyright ª the American Academy of Orthopaedic Surgeons. Unauthorized reproduction of this article is prohibited.

http://dx.doi.org/10.5435/JAAOS-D-16-00607

cruciate ligament (ACL) autograft is anotable factor in determining return-to-sport and reinjury rates, especiallyfor adolescent females with highquadriceps to hamstring strengthratios. Investigating this and similarhypotheses in a systematic fashionmay lead to the development of sex-specific treatment algorithms thatmay optimize clinical outcomes.Here, we review the current liter-

ature on sex-based differences forfive commonly occurring SRIs:stress fracture, ACL injuries, femo-roacetabular impingement (FAI),shoulder instability, and concussion.

Stress Fracture

Since the implementation of Title IXin 1972, the number of females par-ticipating in sports has increaseddramatically at all levels of play. Thus,the number of SRIs has also increased.One injury that first seemed to beparticularly common in this pop-ulation was stress fracture, often seenin the context of hormonal anddietaryirregularities. When the Task Forceon Women’s Issues of the AmericanCollege of Sports Medicine wasassembled in 1992, the term “FemaleAthlete Triad (FAT)” was created todescribe the interrelated pathologiesof disordered eating, amenorrhea,and low bone mineral density (BMD);all three components had to bepresent simultaneously for a diag-nosis of FAT.

In 2007, the American College ofSports Medicine updated the diag-nostic guidelines, and FAT was re-defined to include a constellation ofabnormalities including those relatedto energy availability (EA),menstrualfunction, and BMD.5 Each compo-nent is part of a spectrum rangingfrom normal to increasing degrees ofpathology. The female athlete nolonger must demonstrate pathologyin all three components of the triadto be diagnosed with the syndrome.Determining the true prevalence of

FAT is difficult, especially as the def-inition continues to evolve. Studieshave demonstrated low EA in up to36% of female high school athletes,6

63% of endurance athletes,7 and77% in ballet dancers.8 The samegroup of authors identified men-strual dysfunction in 54% of highschool athletes, 60% of enduranceathletes, and 36% of ballet dancers.In a study of female endurance ath-letes, Melin et al7 reported that 45%had impaired bone health and 25%demonstrated all three componentsof the triad.In 2014, Barrack et al9 reported

that 11% of adolescent female ath-letes in their study population had abone stress injury secondary to FAT.This finding is particularly concern-ing because 90% of peak bone massis accrued by adolescence; a normaladolescent female gains approxi-mately 2% bone mass per year,whereas an amenorrheic female loses2% per year. If young female athletes

fail to maximize their bone massduring the normal period of accrual,they may have an increased risk forosteoporosis and associated fragilityfractures later in life.10 The mostcommon musculoskeletal manifes-tation of the FAT is stress fracture,and females are at a greater risk ofthis complication. In a 2011 sys-tematic review of the incidence ofstress fracture in military and athleticpopulations, Wentz et al11 reportedstress fractures in 9.7% of femaleathletes compared with 6.5% in maleathletes. In the military population,females fared worse than males, witha reported stress fracture incidence ofmore than three times that of males.Acknowledging that athletes of both

sexes might be at risk for impairedbone health resulting from nutritionaland neuroendocrine abnormalities,the International Olympic Committeeconvened in 2014 and published aconsensus statement titled, “Beyondthe FAT—Relative Energy Deficiencyin Sport (RED-S).”12 The term“RED-S” is intended to be a broaderand more comprehensive definitionof pathology secondary to a relativeenergy deficiency that may occur inany athlete, irrespective of sex.12

Highlighting the fact that RED-Smay affect both male and femaleathletes, Tenforde et al13 examinedcomponents of this syndrome inmaleathletes. These authors noted thatmale athletes, like their female coun-terparts, may sustain bone stressinjuries in the setting of nutritional

Dr. Carter or an immediate family member serves as a board member, owner, officer, or committee member of the American Academy ofOrthopaedic Surgeons and the Pediatric Orthopaedic Society of North America. Dr. Ireland or an immediate family member serves as aboard member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons, American College of SportsMedicine, American Orthopaedic Society for Sports Medicine, and the Ruth Jackson Orthopaedic Society. Dr. Johnson or an immediatefamily member serves as a paid consultant to or is an employee of the Orthopaedic Devices Panel and the US Food & Drug Administration;has stock or stock options held in Pfizer; has received research or institutional support from Bergstrom Pharmaceuticals and FlexionTherapeutics; and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons,American College of Sports Medicine, and the Society of Military Orthopaedic Surgeons. Dr. Levine or an immediate family member servesas an unpaid consultant to Zimmer and serves as a board member, owner, officer, or committee member of the American OrthopaedicAssociation. Dr. Bedi or an immediate family member serves as a paid consultant to or is an employee of Arthrex and serves as a boardmember, owner, officer, or committee member of the American Orthopaedic Society for Sports Medicine. Dr. Matzkin or an immediate familymember has received research or institutional support from Zimmer. Neither Dr. Martin nor any immediate family member has receivedanything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject ofthis article.

Sex-based Differences in Common Sports Injuries

448 Journal of the American Academy of Orthopaedic Surgeons


and endocrine abnormalities. Theysuggested that hypogonadotropichypogonadism (characterized inmales by low serum testosterone levelswith concomitant clinical symptoms,such as low BMD, reduced energy andstamina, oligospermia, and decreasedlibido) is analogous to the hypotha-lamic amenorrhea component of FAT.Tenforde et al13 proposed that asubset of male athletes may presentwith a combination of low EA, hypo-gonadotropic hypogonadism, and lowBMD, in which each component existson a spectrum similar to that charac-terizing FAT.13 In addition, just as hasbeen reported for female athletes, maleathletes who seem to be most at riskfor developing RED-S commonlyparticipate in sports emphasizingleanness, including aesthetic sports(eg, gymnastics), endurance sports(eg, running, cycling), and sports witha weight classification (eg, rowing,wrestling).10,14

A recent study on awareness ofFAT among multispecialty physi-cians demonstrated that only 37%ofphysicians across disciplines hadheard of the triad.15 This highlightsthe importance of continued edu-cation for all athletes, coaches, andphysicians about RED-S, includingits signs, symptoms, and at-riskpopulations (both female andmale), so that the potential negativeconsequences of RED-S on long-termreproductive and skeletal health canbe mitigated.

Anterior Cruciate LigamentInjury

Abundant data exist demonstratingthat female athletes are particularlyvulnerable to ACL rupture; the inci-dence of noncontact ACL injuries istwo to eight times higher in femalescompared with males participating inbasketball, soccer, team handball,netball, and alpine skiing.16 Accord-ing to survey data obtained from the

US National Collegiate AthleticAssociation, females who partici-pate in collegiate basketball havemore than a threefold increased riskof sustaining an ACL injury thantheir male counterparts; female col-legiate soccer players have a simi-larly high relative risk of noncontactACL injury (relative risk = 2.75).16

Therefore, given the higher rate ofsports participation among males, theabsolute number of ACL injuriesremains higher for this group than forfemale athletes.Risk factors for ACL injuries have

been classified as nonmodifiable(eg, anatomic, structural, hormonal)or modifiable (eg, neuromuscular,biomechanical). An expert consensusis thatmodifiable factorsmay bemoreimportant in explaining the higherincidence of noncontact ACL injuriesamong female athletes.17

One primary modifiable risk factorfor ACL injury that has been shown todiffer between the sexes is the landingpattern.18 Females tend to exhibitvalgus collapse and increased abduc-tion moments at the knee, both ofwhich are predictive of ACL injury. Inaddition, when performing a singlemini-squat, females tend to exhibit ananteriorly rotated pelvis, contralat-eral pelvic drop, hip internal rotationand adduction, knee valgus, tibia ex-ternal rotation, and foot pronation19

(Table 1). Similarities can be observedbetween the single mini-squat and themechanism of noncontact ACL injury,

which seem to set up the female ath-lete for ACL rupture.Nonmodifiable risk factors for

ACL injury also exist. For example,smaller notch dimensions may pre-dispose individuals to ACL injury.However, a sex-based difference doesnot seem to exist in this respect.20

Other studies that evaluate the roleof bony architecture in ACL injuryrisk have reported that a shallowmedial tibial plateau and steep tibialslopes are risk factors for ACLinjury; these anatomic differenceshave not been shown to be sexdependent.21 Sex-based differencesin the osseous anatomy of the kneehave been reported, including differ-ences in femoral condyle shape, hipversion, and the length of the femurcompared with the pelvic width. Todate, however, no causal relation-ship between these factors and ACLinjury has been proven.Another nonmodifiable risk factor

that has been theorized to correlatewith ACL injury is the changinglevels of circulating sex hormonesthroughout the femalemenstrual cycle;however, data are insufficient to makeany conclusive statement regardingmenstrual cycle, laxity, and the risk ofACL injuries in females.22

Interestingly, Posthumus et al23

demonstrated that genetics likelyplays a role in ACL injury risk; theCOL5A1 gene (which codes foralpha chains of collagen) is associ-ated with an increased risk of ACLinjury in females.

Table 1

Sex-based Differences Observed During Performance of a Mini-squat

Body Region Male Female

Back Flat Lordotic

Pelvis Level; neutral Contralateral drop; anterior tilt

Hip No rotation Internal rotation and adduction

Knee Neutral Valgus

Tibia Neutral External rotation

Foot Flat Pronation

Cordelia W. Carter, MD, et al

July 1, 2018, Vol 26, No 13 449


In terms of treatment and outcomesfor athletes with ACL injury, infor-mation on sex-based differences islacking. Prospective studies investi-gatingwhether sex affects a surgeon’schoice of graft for ACL reconstruc-tion are needed. Similarly, little in-formation is available on whether andhow sex affects postoperative reha-bilitation and return-to-play decisions.Brophy et al24 found that in soccerplayers followed for 7 years after ACLreconstruction, females were morelikely than males to require furtherACL surgery and less likely to returnto play. A 2014 meta-analysis of 13studies demonstrated no differencein graft failure, contralateral ACLrupture, or patient-reported out-comes as a function of the patient’ssex.25 However, the authors of thismeta-analysis concluded that morehigh-quality studies are needed.The incidence of ACL injury

remains markedly higher in femaleathletes than in male athletes, evenafter controlling for sport. In addi-tion, sex-based differences have beenidentified for both modifiable andnonmodifiable risk factors for ACLinjury. However, sex-based differ-ences in treatment and outcomes ofthis injury have not, as yet, beenclearly delineated. More researchstudies on potential sex-based differ-ences in risk factors, treatment, andoutcomes for athletes with ACLinjuries are needed.

Shoulder Instability

Atraumatic ShoulderInstabilityAs themostmobile of themajor joints,the glenohumeral joint depends on acombination of soft-tissue restraints,dynamic muscular forces, and bonymorphology for stability. Owenset al26 investigated the role of osse-ous anatomy in providing shoulderstability and found that a patient

whose glenoid is tall and thin has ahigher risk of instability than onewhose glenoid is short and wide.Subsequent investigators have ob-served that glenoid morphologyvaries markedly by race and sex;27,28

compared with males, femaleshave markedly smaller glenoids,with higher inclination angles.27 Inaddition, height-to-width ratios ofglenoids markedly differ betweenmales and females; the functionalimportance of this finding is that theglenoid is more oval in shape (talland thin) in females and rounder inmales.28 These anatomic findingssubstantiate that females shouldhave higher rates of shoulder insta-bility than males because the glenoidmorphology in females favors insta-bility. The combination of innateosseous vulnerability, increasedshoulder range of motion, and greaterprevalence of generalized ligamen-tous laxity30 in females likely con-tributes to the higher rates ofatraumatic multidirectional shoulderinstability seen in this population.Thus, although sex-based anatomicrisk factors for shoulder instabilityare fairly well characterized, littleinformation is available regardingsex-based differences in treatmentand functional outcomes for patientswith atraumatic shoulder instability.

Traumatic Anterior ShoulderInstabilityIn the general population, the inci-dence of traumatic glenohumeraldislocations is relatively low, with0.08 to 0.24 dislocations occurringper 1,000 person-years.31 The inci-dence of traumatic shoulder insta-bility is more than seven times greaterin the military population, increasingto 1.69 per 1,000 person-years; mostof these dislocations are observed incadets.31 Research on the incidenceof traumatic shoulder instability as afunction of the patient’s sex has re-vealed that traumatic dislocations

occur twice as often in males than infemales.32 In fact, Zacchilli andOwens32 found that males are 2.6times more likely to present to theemergency department with ashoulder dislocation than arefemales. Traumatic dislocations havealso been found to have an inverserelationship with age and a directrelationship to activity level.32

In addition to males having anincreased risk of initial traumaticshoulder instability relative to females,this population has also shown anincreased risk of developing recurrentshoulder instability after an initialtraumatic dislocation. In their investi-gation into the risk factors and func-tional outcomes for young patientswith recurrent shoulder instabilityafter an initial traumatic dislocation,Robinson et al33 found that the meantime to the development of recurrentinstability was 13.3 months, with thepeak risk of recurrence at 24 months.Univariate analysis demonstrated thatage, sex, generalized ligamentous lax-ity, participation in and intensity ofsports, and return to contact sportswere all contributing factors to thedevelopment of recurrent shoulderinstability. However, after multivari-ate analysis, only male sex andyounger age were independently pre-dictive of recurrent instability. Therisk of recurrent instability was lowerfor females of all age groups com-pared with their age-matched malecounterparts.33 Thus, although a va-riety of injury- and patient-related fac-tors may contribute to the risk ofrecurrent shoulder instability, the riskis highest in athletic young males.33

As yet, there has been little investi-gation into possible sex-based differ-ences in the outcomes after surgicalstabilization of the shoulder. In addi-tion to this paucity of data, concernhas been raised that the outcomesmeasures used in clinical researchmaynot be valid for all patients: sex-baseddifferences have been noted for thenormalized scores of commonly used




functionaloutcomesmeasures, suchasthe Constant-Murley score.34 Meth-odologically sound, adequately pow-ered studies that use validated,sex-neutral outcomes measures areneeded to best understand how ath-letes’ sex affects their risk of shoulderinstability as well as its treatment andoutcomes.

FemoroacetabularImpingement

FAI is a condition characterized bybony abnormalities around the hipthat may cause labral tearing anddamage to the articular cartilage,especially in young athletes.35,36

Because the etiology of FAI is poorlyunderstood, the effect of specificsports activities is unclear. Researchhas indicated that repetitive hipmotion may lead to irregular boneformation, particularly in youngerathletes as their physeal platesclose.37 Alternatively, athletes mayhave the same prevalence of radio-graphic FAI as the general population,yet become symptomatic because ofincreased stress through the hip.36,38,39

Sex-based differences in the ace-tabular and femoral morphologyhave been identified in patients withFAI.40 Although pincer lesionsoccur equally in males and females,cam- or combined-type morphol-ogies are more prevalent in males.36

When cammorphology is present inpatients with hip pain, males havelarger alpha angles; in a recentstudy, Nepple et al41 reportedaverage alpha angles of 70.8� and57.6� in symptomatic males andfemales, respectively (Figure 1). Astudy of large cohort of patients withsymptomatic FAI assessed with CTsuggested that females have increasedfemoral and acetabular anteversionwith milder cam-type morphology,whereas males have more restrictedmotion and larger and broader cam-type morphology.42 In addition to

increased hip anteversion,43-46 femalesalso have a higher prevalence of ace-tabular dysplasia compared withmales. In their recent series, Kapronet al38 identified dysplasia in 21% ofcollegiate female athletes. This findingis relevant for surgical planning be-cause overresection of a pincer lesioncan result in instability.47

Symptoms of FAI and labral tearsinclude intermittent anterior hip orgroin pain, locking, and popping.Activities requiring hip flexion orpivoting often elicit symptoms in bothmale and female athletes.36 Kapronet al38 found that, in female athletesonly, the response to impingementtesting did not correlate well with thepresence of radiographic FAI. Onpresentation, females reportedworse function and decreased activity,despite a greater hip range of motionthan that of males. Interestingly, this

finding does not seem to correlate withthe severity of the disease becausemales often have larger cartilagedefects and labral tears41 (Figure 2).Although females present earlier inthe disease process than males do,males are more likely to undergobilateral surgery within 2 years.48

Of note, symptoms of FAI can beseen in females with minimal bonyabnormalities. This occurrence maybe attributed to physiologic differ-ences such as increased laxity, lessmusclemass, andoverall greater rangeof motion compared with males.43,45

Awareness of alternate etiologies ofpain, particularly in females, such asstress fractures, iliopsoas dysfunction,sacroiliac pathology, ovarian cysts,and endometriosis, is important. Man-agement of confirmed FAI does notdiffer between males and females be-cause a nonsurgical approach, in-cluding physical therapy, activitymodification, and anti-inflammatorymedication, is recommended as first-line treatment.35,36 Typically, sur-gical intervention entails somecombination of labral repair, ace-tabular osteoplasty, and femoralosteoplasty that can be conductedarthroscopically. Surgical techniquesare not sex dependent; however, care-ful consideration of the underlying

Figure 1

Radial reformatted MRI demonstratingthe method of assessing the alphaangle in femoroacetabularimpingement. It is measured bydrawing a best-fit circle on the femoralhead (a); a line from the center of thefemoral head that bisects the femoralneck (b); and a line from the center ofthe femoral head to the location wherethe femoral head no longer follows acircular contour (c).

Figure 2

Intraoperative photograph of the hipdemonstrating a labral tearextending into the chondrolabraljunction. This pattern of injury is morecommonly seen with cam lesions.


July 1, 2018, Vol 26, No 13 451


bony abnormalities is essential indetermining appropriate resection.35,36

Prognosis after surgery is favorable,with return to play reported in 73%to 92% of patients.49,50 Markedlyimproved functional outcome scoresafter hip arthroscopy have been re-ported, with no difference betweensexes in patients aged,45 years.51,52

Further investigation of sex-baseddifferences in the clinical presentation,relevant anatomy, and surgical man-agement of FAI is necessary to eluci-date factors markedly associatedwith patient outcomes. For example,recognizing that females have higherrates of pelvic anteversion coupledwith greater ligamentous laxitymight suggest that surgical osteo-plasty would be beneficial in thispopulation, even in the setting ofradiographically smaller impinge-ment lesions. Rigorous scientificinvestigation that either confirms orrefutes this type of clinical hypothesisis needed.

Concussion

Concussions sustained during ath-letic participation have become in-creasingly common; the CDCreported that 249,000 children (aged#19 years) were treated in anemergency department for sports-related concussion in 2009.53 Thisnew wealth of experience treatingyoung athletes with concussions ledsome investigators to hypothesizethat sex-based differences exist inboth the incidence of and the symp-tomatology after a sports-relatedconcussion.54 In a recent study,Zuckerman et al55 demonstrated ahigher incidence of concussion infemales participating in sports suchas soccer, basketball, and lacrosse.Large epidemiologic studies haveconsistently found that female ath-letes sustain markedly more concus-sions than male athletes; in somestudies, the number of concussions

sustained by female athletes is doublethe number sustained by male ath-letes.54,56 These differences are mostcommonly seen in sports such asbasketball, soccer, and volley-ball.54,56 Some authors have addi-tionally demonstrated that femaleathletes sustain more severe con-cussions than do males, withgreater deficits in cognitive functionreported and a longer recovery pe-riod required than their male coun-terparts.57-59

Why females seem to have a higherrisk of sustaining a concussion com-pared with males remains uncertain.Several theories have been positedand primarily focus on anatomicand biomechanical differences: first,females typically have more slendernecks and smaller heads comparedwith males and thus experiencegreater reactive forces when headtrauma is sustained. Biomechanicalstudieshavedemonstrated that femalescan experience nearly 50%more headacceleration during head trauma thanmales.54,60 Although it has also beentheorized that a female’s relativelyweak neck musculature may provideless protection against concussionthan a male’s neck musculature,recent research suggests thatdynamic cervical stabilization re-sponses may play a larger role thanneck strength in mitigating headimpact severity.61 Finally, in additionto the sex-based differences in anat-omy and biomechanics that likelymediate an athlete’s experience ofconcussion, hormonal differencesbetween males and females mayalso play a role. Studies haveshown that estrogen has differen-tial effects on the brain after trauma,with animal studies suggesting agreater detrimental effect of estrogenin females.54,62

It has also been argued that thedocumented differences between thesexes with regard to concussion inci-dence and severity may simply bethe product of reporting bias. Male

athletesmaybemore likely than femaleathletes to hide concussions and fail toreport them for fear of not being ableto continue playing or to participatein sports.63 Gender stereotypes mayreinforce this behavior, with boyswanting to appear “manly” aftersustaining a concussion and “tough-ing it out.”Much remains to be elucidated

regarding sex-based differences inconcussion incidence and severity.Ultimately, team physicians shouldhave a high index of suspicion forconcussion with any head traumasustained in sports, regardless of theathlete’s sex.

Summary

Sex-based differences are common inmedicine, occurring at both themicro(cellular) and macro (whole organ-ism) levels. Some sex-based differ-ences inmusculoskeletalmedicine arefairlywell characterized, suchas thoseseen in patients with degenerativejoint disease of the knee and fragilityfractures of the hip. Despite theseinitial successes in advancing knowl-edge of sexual dimorphism in the fieldof orthopaedic surgery, research thatstrives to detect, describe, anddelineatesex-based differences in musculoskele-tal disease is a field of study thatremains in its infancy,bothat thebenchand in the clinics.Our review of the existing literature

on sex-based differences in commonsports injuries demonstrates the con-tinued need for focused efforts atstudying these differences becauseultimately, a patient’s sex will likelyaffect his or her clinical outcome. It iscritical that we continue to enhanceour understanding of the differencesamong patients and the role thesedifferences play in mediating eachpatient’s experience of, and treatmentoutcomes for, various musculoskele-tal diseases—including stress fracture,ACL injury, shoulder instability, FAI,




and concussion. Devising scientificstudies that investigate sex-specifichypotheses (eg, do females with ACLinjury have lower reinjury rates afterquadriceps autograft reconstructionthan males?) may lead to the devel-opment of evidence-based sex-specifictreatment algorithms for varioussports injuries and, ultimately, toimproved musculoskeletal care forall athletes.

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