Anterior Cruciate Ligament Injury in Female Athletes: Why are women so vulnerable?: Literature review

Physiotherapy September 2000/vol 86/no 9

464

Introduction

‘The paramount destiny and mission ofwoman is to fulfil the noble and benignoffices of wife and mother. This is the lawof the Creator and the roles of societymust be adapted to the constitution ofthings’ (Bradley, 1872).

Fortunately the above statement is notrepresentative of the current climate ofopinion, but it serves to illustrate that withsuch ideas recommending subjugation ofwomen in 19th century society, it is notsurprising that female participation in sportwas quite limited until recent times.

A defining moment in the involvement offemales in sport in the US was Title IX of the Education Amendment Act of 1972(Bradley, 1872), the final regulations ofwhich required equal opportunities inathletics; the US Congress implementedTitle IX in 1974. Since this statute there has

been a quantum leap in the number offemales participating in sport at all levels.Before Title IX fewer than 10,000 femalescompeted in collegiate sport (Ireland et al,1997). Recent figures published by theNational Collegiate Athletic AssociationSurveillance System reported that there were107,605 female participants in 16 sports(NCAA, 1994-95).

Both participation and disciplines havechanged; women have ventured fromtraditional, non-contact sports such asswimming and track and field to physicalgames like basketball, hockey and soccer.Women’s sports, once dominated by a slow,defensive style are now played with speed,precision and power (Moeller and Lamb,1997).

Increased injury rates have accompaniedthe rise in participation and while foot,shoulder and patellofemoral problems arecommon, so too is disruption of the anteriorcruciate ligament (ACL) (Arendt, 1996).Such injuries are particularly catastrophicdue to the length of time lost from sport andthe financial implications of care (Freemanet al, 1995).

Sports in the US associated with femaleACL injury are quoted as soccer, basketball,skiing, volleyball and gymnastics (Hustonand Wojtys, 1996). In Europe soccer is againimplicated, along with handball and skiing(Bjordal et al, 1997). Injuries occur moreoften in competitive games than in practicematches (Anderson et al, 1991). This hasbeen stated as up to three times thelikelihood and appears to be due to theincreased intensity of the competitive matchatmosphere (Garrick and Requa, 1978).

ACL injury rates of both sexes have beencompared at all levels from junior to éliteprofessional. Bjordal et al (1997) comparedACL injury rates in 15- to 18-year-oldfootballers, and found that females were 5.4times more likely to sustain injury thanmales.

Anterior Cruciate LigamentInjury in Female Athletes: Why are women sovulnerable? Literature review

Summary Female athletes are more likely to suffer certain sports-related injuries than their male counterparts. The knee joint inparticular is a troublesome site and the anterior cruciate ligamentis a structure especially susceptible to injury.

Many explanations regarding possible contributing factors to thisincreased prevalence have been put forward, including sex-relatedskeletal variation such as pelvic width, femoral anteversion,femoral intercondylar notch dimensions, and increased Q-angle.

Some of these explanations appear to be dubious. However,recent research into pronation control, ligament laxity,neuromuscular characteristics and the effect of menstrualhormones on the ACL has produced some enlightening data.

Awareness of the possible causes of increased ACL injury rates inwomen and girls provides a basis for strategies to help to preventthis potentially devastating injury.

It seems that co-ordination and agility work combined withproprioceptive exercises could play a large part in reducing injuryrates.

Key WordsACL, female, injury, athlete.

by Trevor Lewis

Lewis, T (2000). ‘Anteriorcruciate ligament injuryin female athletes: Whyare women so vulnerable?Literature review’,Physiotherapy, 86, 9, 464-472.


465Professional articles

Author and Address forCorrespondence

Mr Trevor LewisGradDipPhys MCSP is aclinical physiotherapyspecialist(musculoskeletal service)in the physiotherapydepartment at The RoyalLiverpool UniversityHospitals, Prescot Street,Liverpool L7 8XP.

e-mail:[email protected]

This essay was submittedthis year as courseworktowards a master’s degreein sports science at JohnMoores’ University,Liverpool.

It was received byPhysiotherapy on June 28,1999, and accepted onMarch 1, 2000.

Funding

This research was fundedby the Hospital SavingsAssociation.

The NCAA Injury Surveillance System inthe 1989/90 season reported that femaleathletes injured their ACL at a rate of 7.8times more than male athletes (Pearl, 1993).Malone et al (1993) compared injury rates by sex in college basketball players andreported females as eight times more likelyto sustain ACL injury.

In the US in 1988 participants in theOlympic basketball trials completed aninjury questionnaire. The population sampleconsisted of 64 women and 80 menadjudged to be the country’s élite athletes.Thirteen of the women had sustained anACL injury compared to only three of the 80men. Eight women had undergone ACLreconstruction compared with three of themen (Ireland and Wall, 1990).

The higher ratio of female injury was saidto be understandable due to the steep rise intheir participation levels (Protzman, 1980).A high incidence of stress fractures wasobserved in women when they first enteredmilitary service (Cox and Lenz, 1984). Withtime the injury rates of these fractureseventually equalised with those of men;however, this has not been the case withfemale ACL injury rates.

Sports involving physical contact, ballisticmovement and weight-bearing rotation suchas basketball, soccer and volleyball are notedfor producing ACL injuries (Moeller andLamb, 1997). In potentially less injurious,non-contact track events, however, Jackson etal (1980) observed double the injury rateamong female athletes. Five non-contactmechanisms of ACL injury have beenrecognised: planting and cutting (a suddenchange in body direction following foot-to-ground contact), straight-knee landing,sudden deceleration, pivoting, and one-stepstop landing with knee hyperextension(Moeller and Lamb, 1997).

Given these findings, a review of some ofthe most commonly cited factors which aresaid to contribute to female ACL injury isneeded to clarify which of them aresignificant in the aetiology of such injuries.

Anatomy and BiomechanicsThe ACL helps to limit anterior translationof the tibia on the femur. It works with theposterior cruciate ligament to controlgliding and rolling of the tibia on the femurduring normal flexion and extension. Itprovides secondary restraint limitinginternal rotation of the tibia and also seemsto make at least a minor contribution torestraining both varus and valgus stresses

across the knee joint (Norkin and Levange,1992).

The ligament is made up of two bands: the anteromedial and posterolateral (andoccasionally there is also an intermediateband). The ACL runs from the postero-medial portion of the lateral femoralcondyle through the femoral intercondylarnotch in an inferior, anterior and medialdirection to an area lateral to the medialtibial eminence. The posterolateral band istightest during knee extension, and theanteromedial band is tightest in knee flexion(Moeller and Lamb, 1997).

The twisted configuration of the ACLfibres and the shape of the femoral condylesallow for the screw-home mechanism of theknee during the final 20° of extension whenthe tibia externally rotates on the femur.The ligament is under varying degrees oftension in all positions of motion, butmaximal tibial anterior translation isobserved at 30° flexion when both the ACLbands display their minimum tension(Torzilli et al, 1981).

Schultz et al (1984) identified mechano-receptors in the ligament, and Yahia andNewman (1991) and Zimny and Wink(1991) have both reported that mechano-receptor density is highest at the proximaland distal bony attachments. The proprio-ceptive function of the ACL has beenintensively studied. Schutte et al (1987)stated that 1% of the ligament’s dry weightwas neural tissue and Barrack et al (1989)observed significant proprioceptive deficit inknees with ACL disruption. A neurologicallink between the ACL and the cerebralcortex has been established from corticalEEG signals produced by ACL stimulationduring arthroscopy (Pitman et al, 1992).

Structural FactorsThe ‘miserable malalignment syndrome’ ofhigh Q-angle, increased pelvic width,anterverted femur, valgus knee, andpronated foot (James, 1976) is often quotedas an explanation for increased knee injuryrates in females (see figure overleaf). Thedifferent components of this syndrome willnow be discussed separately along with areview of more recent work concerning jointlaxity, sex-related neuromuscular charact-eristics, and menstrual hormones.

Q-angleThe Q-angle is described as being formedbetween the vectors for the combined pullof the quadriceps femoris muscle and the


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patellar tendon (Hungerford and Barry,1979). Hahn and Foldspang (1997) invest-igated 339 athletes and observed Q-angleasymmetry within subjects, and theirexperiment also found that the Q-angle wasgreater in females.

There is no strict agreement regardingstandardised reference values, but Q-anglesexceeding 15° in males and 20° in femalesare considered abnormal (Horton and Hall,1989). Anecdotally, increased female Q-angle is often explained by femalespossessing a wider pelvis than males, thusincreasing the obliquity of the femora andconsequently the valgus orientation of theknee (Moeller and Lamb, 1997; Ireland et al,1997; Caylor et al, 1993).

There is a recognised relationship betweenhigh Q-angle, patellar maltracking andanterior knee pain, and several authors havespeculated that this sex-related anatomicaldifference may also lead to increased risk ofACL injury (Hutchinson and Ireland, 1995;Moeller and Lamb, 1997). However, severalstudies have found no relationship betweenQ-angle and predisposition to ACL injury(Gray et al, 1985; Loudon et al, 1996). Not only is there no clear link between ACL injury and Q-angle but there is noconsensus in the literature as regards Q-angle measurement. In a review ofliterature regarding the Q-angle, Livingston(1998) states that it is question-able whether

a static Q-angle measurement has anybearing on dynamic activities. The currentliterature suggests that the Q-angle is anunreliable measurement and even if it werereliable its role in female ACL injury isuncertain.

Pelvic WidthFemales are said to have a wider pelvis thanmales and this is quoted regularly in theliterature (Hutchinson and Ireland, 1995;Ireland et al, 1997; Moeller and Lamb,1997). Ireland et al (1997) state that a widerfemale pelvis increases ACL injury risk bycreating a greater coxa vara/genu valgumalignment with a concurrent increase intibio-femoral rotational force, thus imposinggreater stress on the ACL. Unfortunately noresearch was presented by these authors tosubstantiate this comment.

Even though soft tissue outlines maysuggest otherwise, there is a significantamount of evidence to refute the idea thatthe female pelvis is wider than that of males.The absolute width using anterior superioriliac spine measurements (Guerra et al,1994) biiliocristal (Atwater, 1990), andbitrochanteric measurements (Horton andHall, 1989) was found to be virtually thesame in both sexes. Despite the frequentassumption of increased pelvic width infemales, this notion is not well founded.Studies that have been conducted in this

Wider pelvis

Femoralanteversion

Less developedVMO

External tibialtorsion

More developedthigh musculature

Narrower pelvis

Internal or neutraltibial torsion

Genu varum

Less flexibility

VMO hypertrophy

Genu valgum

Increasedflexibility/hyperextension

Less muscular thighdevelopment

Lower extremity alignments that may predispose athletes to over-use problems of hips and knees, especially ACL and patellofemoral injuries: A females, B males. Reproduced with permission from Fu, F H and Stone, D A (1984). Sports Injuries: Mechanisms, prevention, treatment, Williams and Wilkins, Philadelphia

A B

Narrow notch Wider notch



area strongly refute anatomical sex diff-erences and thus any possible contributionto female ACL injury.

Femoral Intercondylar NotchAn association has been suggested between asmall intercondylar notch and sustaining anACL tear (Laprade and Burnett, 1994).Notch dimensions have been widelyreported as a causative factor in higherfemale ACL injury rates due to womenpossessing a smaller ‘notch width index’(NWI) than men (Souryal and Freeman,1993). Souryal et al (1988) defined the NWIas ‘the ratio of notch width to that of thedistal femur at the level of the poplitealgroove’. This is measured using a ‘tunnelview’ radiograph, and a ‘normal’ ratio wasquoted as 0.2. Souryal et al (1988) proposedprophylactic bracing and notchplasty in theunaffected knee of patients who had tornthe contralateral ACL and whose NWI wasbelow normal. These recommendationsassume that notch anatomy is the mostdecisive component in ACL injury.

Muneta et al (1997) investigated whetherACL dimensions could be predicted bynotch width and found that both narrowand wide notches house the same size ACL.They hypothesised that injury is due tonormal-sized ligaments being ‘frayed’ instenotic notches.

However, this was a cadaveric study of only16 elderly knees (average age 74.8 years)and using ACL moulds cast from dentalsilicone to arrive at their results. Possibleage-related changes in either bone orligament were not mentioned. Additionally,the accuracy of their ligament moulds to the biological ACL proportions was notevaluated.

Teitz et al (1997) compared bilateral NWIin 40 male and 40 female patients usingradiographs. They found that NWI weresymmetrical within subjects and there wasconsiderable overlap in dimensions betweensexes. Females displayed a smaller NWI thanmales but this was not statistically significant,There was also no difference in NWIbetween patients with and without ACLtears.

Disagreement between studies may be aproduct of different imaging techniquesused to map the dimensions of the notch.Magnetic resonance imaging (MRI) hasdisplayed no difference in NWI betweennormal and ACL deficient knees (Herzog etal, 1994). MRI was also used by Staeubli et al(1999) on 51 knees (25 females, 26 males)

to assess any sex-related differences. Theyfound that the absolute widths of the ACLwith respect to intercondylar notch widthswere not significantly different betweensexes. It seems that more contemporaryresearch using the anatomical precision ofMR images is gradually rejecting femoralnotch dimensions as a predictive factor inACL injury.

Subtalar PronationPronation is defined as a combined motioninvolving subtalar eversion, foot abductionand ankle dorsiflexion (Norkin andLevange, 1992). Subtalar pronation andinternal rotation of the tibia occur con-currently in the contact phase of the gaitcycle and the ACL becomes taut with tibialrotation (Woodford-Rogers et al, 1994).Coplan (1989) reported that abnormalpronators were found to have increasedpassive knee rotation at 5° of knee flexionand that there is a very importantrelationship between pronation androtational knee joint laxity. It has beenconcluded that prolonged pronation of thesubtalar joint produces increased internaltibial rotation which in turn stresses themedial structures of the knee (Vogelbachand Combs, 1987). The navicular drop testinvolves measuring navicular height insitting in sub-talar neutral, then in fullweight bearing, and is described as ameasure of pronation in an experiment byWoodford-Rogers et al (1994). Drop heightwas recorded in 22 ACL-injured athletes (14 male and 8 female) and compared with22 age- and sport-matched controls. Astatistically significant difference was notedwhere non-injured subjects dropped 5.9 mmwhile ACL-injured athletes dropped 8.4 mm.Loudon et al (1996) observed similar resultsand found that excessive navicular drop andexcessive subtalar joint pronation werestatistically significant discriminatorsbetween ACL-injured and non-injuredgroups. It seems that a consensus isdeveloping regarding a relationship betweenexcessive pronation and ACL injury, butexperiments to establish any significantdifferences between males and females havenot been carried out.

Femoral AnteversionFeagin et al (1982) discussed the importanceof femoral rotation in the transverse plane asa mechanism of injury to the ACL. Tiberio(1987) has stated that internal rotation ofthe femur predisposes an individual to


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excessive pronation of the subtalar joint andthus concomitant ACL injury. The angle ofanteversion is said to be measurable usingthe clinical method described by Ruwe et al(1992). The patient is placed prone with theknee flexed to 90°. The greater trochanter ispalpated while passive medial and lateral hiprotation are conducted. The trochantershould be most prominent in neutralrotation; anteversion is present if there ismedial hip rotation greater than 15°.

Loudon et al (1996) used the above test toassess whether there was a relationshipbetween femoral anteversion and theprevalence of non-contact ACL injury. Theirstudy found no difference in anteversionbetween ACL-injured and non-injuredknees. However they conceded that a weight-bearing measurement might have yieldeddifferent results. No other work has beenundertaken to investigate the role of femoralanteversion concerning either any possiblesex-related differences or the role ofanteversion in ACL injury per se. Furtherwork needs to be undertaken in this area.

Joint LaxityIt has long been suggested that there is arelationship between joint laxity and jointinjury including ACL injuries in females(Nicholas, 1970). Huston and Wojtys (1996),using arthrometric measurements, foundthat both female athletic and non-athleticcontrols exhibited more anterior tibial laxitythan their male counterparts. Beck andWildermuth (1985) stated that ligamentouslaxity can be related to conditioning asmuch as to hereditary factors. This state-ment appears to be supported by the work of Huston and Wojtys (1996) who found that female athletes tended to have lessligamentous laxity than sedentary females.

Woodford-Rogers et al (1994), also using aKT-1000 arthrometer, found that anteriorknee joint laxity was significantly greater inACL-injured subjects than in non-injuredsubjects. Knapik et al (1991) found that kneejoint laxity has no direct relationship withACL injury in female athletes. However,their study assessed joint flexibility usinggoniometry against active range of motionrather than with arthrometry. Loudon et al(1996) investigated the discriminatory value of knee recurvatum in female athletesand the prevalence of non-contact ACLinjury. They found that subjects with knee hyperextension had a statisticallygreater predisposition to ACL injury. Thecontemporary trend of measuring joint

laxity using arthrometers appears to beproducing a consensus regarding the role ofjoint laxity in female ACL injury. It has beenstated that individuals with hypermobilejoints often have concomitant motor delaywith proprioceptive deficits (Russeck, 1999).This means that female ACL injury in jointlaxity states could be attributed to motordeficit as much as hypermobility.

Neuromuscular PerformanceAnecdotally, Beck and Wildermuth (1985)suggested that the main reason behind thehigher incidence of non-contact ACL injuryin females was a result of inadequate motorskills. Studies have shown that the ACLoperating in isolation is not capable ofwithstanding the forces produced across theknee during sporting activity (Woo et al,1991). A reflex arc between the ACL and thehamstrings mediates protective reflexcontraction of these muscles when theligament is stressed which limits anteriortibial translation (Skoglund, 1973; Hagoodet al, 1990).

Huston and Wojtys (1996) investigatedEMG neuromuscular patterns along withlower extremity muscle strength, endurance,and muscle reaction times and recruitmentorder in response to anterior tibialtranslation by arthrometer. Sixty maleathletes, 40 female athletes, and 40 healthynon-athletic controls from both sexes wereinvestigated. Significantly less musclestrength and endurance was demonstratedin female athletes and the musclerecruitment order in some female athleteswas noticeably different. They relied on thequadriceps muscles in response to anteriortibial translation; this muscle group being anACL antagonist. The other three groupsrelied more on their hamstring musclegroup.

Female athletes were also weaker in thehamstrings and quadriceps and also tooksignificantly longer to generate maximalhamstring torque.

Huston and Wojtys’ careful studyinvestigated female athletes from basketball,field hockey, gymnastics and volleyball.Larger numbers of males and femalesshould be tested across a wider range ofsports in order to confirm these results.

Hormonal/Menstrual Factors Throughout their sporting lives, femaleathletes are subject to cyclical variation inendogenous hormones and possiblyexogenous hormones via oral contra-



ceptives. Recent research has investigatedthe influence of hormones on ligaments,and oestrogen and progesterone receptorshave been isolated in the ACL (Liu et al,1997). Their research found that collagensynthesis was significantly reduced withincreasing estradiol concentrations. Thesubsequent structural changes were said toresult in reduced strength of the ACL,rendering the ligament more susceptible toinjury. Slauterbeck et al (1999) investigatedthe effect of experimentally increased serumoestrogen levels on failure load of the ACL, and found that load-at-failure wassignificantly reduced in the experimentalgroup (446 ± 54 N) compared to that of a control group (503 ± 48 N). Theexperimenters report that elevatedoestrogen levels produce a reduction in the tensile strength of the ACL. The work ofLiu et al (1997) and Slauterbeck (1999) was conducted using animal models. Liu et al (1996) observed similar results in anexperiment using human tissue. Wojtys et al(1998) collected data from 40 femaleathletes with ACL injury regarding mech-anism of injury, menstrual cycle, contra-ceptive use and previous injury. A statisticallysignificant association was found with injuryduring the ovulatory phase of the cycle whenoestrogen levels are high (days 10-14) andwith reduced injury likelihood in thefollicular phase (days 1-9) when oestrogenlevels are lower. Thus sex hormones may bea factor in the knee ligament problems inwomen. However, oestrogen is said to affectthe central nervous system and motorfunction (Wojtys et al, 1998). This meansthat impaired muscle recruitment orcompromised co-ordination could be just assignificant as diminished ACL tensilestrength in ovulatory phase injury.

DiscussionTraditional explanations for female ACLinjury implicating alignment (Q-angle,pelvic width, femoral anteversion andconfiguration of the femoral intercondylarnotch) appear spurious and withoutscientific basis in the current literature.

The literature reviewed in this articleindicates a consensus of opinion recognisingthe effect of subtalar pronation control,ligamentous laxity, neuromuscularperformance and menstrual hormones inincreased female ACL injury rates. This goes some way to negate the ‘isolatedcomponent’ mode of thought and suggests a multifactorial basis to the problem.

The work of Huston and Wojtys (1996) hasprovided data regarding a delay in theprotective hamstring reflex in females.Tibone et al (1986) found that simplehamstring strengthening alone was notenough to improve voluntary or reflex levelhamstring control. Lutz et al (1993) showedthat closed kinetic chain exercises wereeffective in increasing the level of hamstringco-contraction in ACL patients. Ihara andNakayama (1996) found that the reflex arcbetween the ACL and hamstrings can beshortened with training using wobbleboards. These researchers also found thatsimple hamstring strengthening had noeffect on the reflex arc.

Wojtys et al (1996) investigated theneuromuscular effects of training andconditioning at the knee joint. Four groupsof subjects were assessed: an isokinetically-trained group; an isotonically-trained group;a third group trained with agility exercises;and a control group. The agility exercisesconsisted of figure-of-eight, backwards andsideways running, sliding board work andone-legged hops. It was found that themuscle response time to anterior tibialtranslation was significantly reduced ingastrocnemius and the medial hamstrings inthe agility group. No such improvement wasnoted in the other three groups.

Caraffa et al (1996) conducted a pro-spective, controlled study of 600 soccerplayers on 40 teams during three fullseasons. The prevalence of injury of the ACLin 300 soccer players who participated inproprioceptive training was significantlylower (a mean 0.15 injury per team) thanthat in a group of 300 players who did notparticipate in proprioceptive training (amean 1.15 injuries per team). Griffis et al(1989) investigated the effect of modifyingfemale athletes’ technique on ACL injury,plant-and-cut, straight-leg-landing, and one-step stop were replaced with rounding offturns, knee flexion on landing and three-step stop. A significant decrease in non-contact ACL injury occurred when thesetechniques were taught prospectively.

It seems fair to conclude that if protectivemuscle reaction times can be reduced withproprioceptive, co-ordination and agilityregimes then this could come some way toreducing female ACL injury rates. Whethersuch training regimes would be effective inreducing particularly high injury ratesduring the ovulatory phase of the menstrualcycle (Wojtys et al, 1998) has not yet beeninvestigated.


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Excessive subtalar pronation has beenfound to be a predictive factor in non-contact ACL injury and it seems reasonableto suggest that proprioceptive and co-ordination work may also improve dynamiccontrol of pronation. This would thenreduce the concomitant stress on the ACL.This is only an hypothesis but could beproved experimentally using pre- and post-regime navicular drop measurements. Nowork has been conducted to investigate theeffect of orthotics on pronation control in relation to ACL injury rates but this is said to be popular in the treatment ofpatellofemoral pain (Tria et al, 1992).

Pre-season screening is becomingincreasingly popular (Knapik et al, 1991)and the predictive factors in female ACLinjury could be identified at this stage.Obviously resource issues come into play as not all clubs have access to EMG andarthrometry equipment. However, the workof Carrafa et al (1996) and Griffis et al (1989)appears convincing with respect to the effectof proprioceptive and co-ordination work onreducing ACL injury rates. Prophylacticimplementation of such regimes seemsworth while and would be simple andinexpensive.

Physiotherapists and coaches working withboth male and female athletes could benefitthe players by making such exercises acomponent of rehabilitation and training,and there is a significant amount ofliterature to act as guidance in compilingsuch regimes (Griffis et al, 1989; Ihara andNakayama, 1986; Lutz et al, 1993; Wojtys et al,1996).

ConclusionIf ACL injury rates are to be optimallyminimised we must be able to identify thoseathletes at greatest risk. Pre-season screeningof athletes is a useful tool and could proveinvaluable in identifying athletes with pre-disposing factors to anterior cruciateligament injury.

Physiotherapists, doctors and coachesinvolved in screening, training and treatingfemale athletes should be aware of thewarning signs and consider implementingbasic and then sport-specific regimes toimprove proprioception, agility andneuromuscular co-ordination as a pro-phylactic measure. While the aetiology offemale ACL injury is becoming clearer, thisremains an area for future research.

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Key Messages

� In certain sportsfemale athletes aresaid to be up to eighttimes more likely tosuffer anterior cruciateligament disruptionthan their malecounterparts.

� These injuries arelargely non-contactand are dependentupon certain intrinsicfactors.

� There is evidencethat sub-talarpronation control,ligamentous laxity andneuromuscularperformancecharacteristics playsignificant roles infemale ACL injury.

� Recent research alsoimplicates menstrualhormones in femaleACL injury.

� Pre-seasonscreening is a usefultool in determiningthose at risk ofanterior cruciateligament disruption.

� Proprioceptive, co-ordination andagility exercises havebeen found toimprove ‘ACL-protective’ EMGcharacteristics at theknee.

Documents

Anterior Cruciate Ligament Injury in Female Athletes: Why are women so vulnerable?: Literature review