Rev. bras. ortop. vol.52 suppl.1

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

w w w . r b o . o r g . b r

Original

Article

Prevalence

of

femoroacetabular

impingement

morphology

in

asymptomatic

youth

soccer

players:

magnetic

resonance

imaging

study

with

clinical

correlation

夽

Anthony

Kerbes

Yépez

,

Marcelo

Abreu

,

Bruno

Germani

,

Carlos

Roberto

Galia

a_{SantaCasadePortoAlegre,DepartamentodeCirurgiaOrtopédica,PortoAlegre,RS,Brazil} b_{HospitalMãedeDeus,DepartamentodeRadiologia,PortoAlegre,RS,Brazil}

c_{UniversidadeFederaldoRioGrandedoSul,HospitaldeClínicasdePortoAlegre(HCPA),DepartamentodeCirurgiaOrtopédica,Porto}

Alegre,RS,Brazil

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Articlehistory:

Received30November2016 Accepted26January2017 Availableonline24June2017

Keywords:

Femoroacetabularimpingement Hipjoint

Soccer

Magneticresonanceimaging

a

b

s

t

r

a

c

t

Objective:To determine the prevalence of femoroacetabular impingement morphology (FAIM),cam-orpincer-type,bymagneticresonanceimaging(MRI)inasymptomatic ado-lescentsoccerplayers,andtoevaluatethepossiblecorrelationbetweenalterationsonMRI andclinicalexaminationfindings.

Methods:Across-sectionalstudywasconductedtodeterminetheprevalenceofFAIMin asymptomaticyouthsoccerplayersaged13–18years.Atotalof112hipsin56players(mean age15.3years)wereevaluatedbyMRI.Imageswereexaminedbytwomusculoskeletal radio-logistsforsignsofFAIM.Cam-type(impingement)deformitywasdiagnosedbyalphaangle ≥55◦

orhead–neckoffset<7mm.Pincer-type(impingement)deformitywasdiagnosedby center-edgeangle(CEA)≥35◦

oracetabularindex≤0◦

.OtherMRIchanges,characteristic ofFAIM,wereobserved.Clinicalexaminationwasperformedtodeterminetherangeof motion(ROM)ofthehips.Inaddition,specifictestsforanterolateralandposteroinferior impingementwereperformed.

Results:TheprevalenceofMRIfindingsconsistentwithFAIMamongthisyoungpopulation was84.8%(95/112).Thealphaanglewas≥55◦

in77.7%(87/112)ofhips,whiletheCEAwas alteredin10.7%(12/112)ofhips.QualitativeMRIfindingsconsistentwithFAIMwerehighly prevalent,andincludedlossofsphericityofthefemoralhead(77%),osseousbump(44%), femoralneckedema(21%),andacetabularosteitis(9%).Theanteriorimpingementtestwas positivein15%ofthehipsevaluated.

夽

StudyconductedattheUniversidadeFederaldoRioGrandedoSul,FaculdadedeMedicina,HospitaldeClínicasdePortoAlegre(HCPA), DepartmentofOrthopedicSurgery,PortoAlegre,RS,Brazil.

∗ _{Correspondingauthor.}

E-mail:[email protected](A.K.Yépez).

http://dx.doi.org/10.1016/j.rboe.2017.06.005

Conclusion: YouthsoccerplayershaveahighprevalenceofFAIMasdiagnosedbyMRI.There isnocorrelationbetweenphysicalexaminationfindingsandMRIevidenceofFAIMinthis population.

©2017PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradeOrtopediae Traumatologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Prevalência

da

morfologia

de

impacto

femoroacetabular

em

jogadores

de

futebol

juvenil

assintomáticos:

estudo

de

ressonância

magnética

com

correlac¸ão

clínica

Palavras-chave:

Impactofemoroacetabular Articulac¸ãodoquadril Futebol

Ressonânciamagnética

r

e

s

u

m

o

Objetivo:Determinaraprevalênciadamorfologiadeimpactofemoroacetabular(MIFA),tipo camoupincer,porressonânciamagnética(RM)emjogadoresdefuteboladolescentese assintomáticos,bemcomoavaliarapossívelcorrelac¸ãoentreasalterac¸õesobservadasna RMeosachadosdoexameclínico.

Métodos: EsteestudotransversaltevecomoobjetivodeterminaraprevalênciadeMIFAem jogadoresdefuteboljuvenilassintomáticos,comidadeentre13e18anos.Umtotalde112 quadrisde56jogadores(idademédia15,3anos).Asimagensforamexaminadaspordois radiologistasmusculoesqueléticos,comoobjetivodeidentificarsinaisdeMIFA.A deformi-dade(impacto)dotipocamfoidiagnosticadaquandooânguloalfa≥55◦

oudesvioentre acabec¸aeocolofemoral<7mm.Adeformidade(impacto)dotipopincerfoi diagnosti-cadaquandooângulocentro-borda(ACB)≥35◦_{ouíndiceacetabular≤0}◦_{.Outrasalterac¸ões}

característicasdeMIFAforamobservadasnaRM.Aamplitudedemovimento(ADM)dos quadrisfoideterminadaapartirdeumexameclínico.Alémdisso,foramrealizadostestes específicosparaimpactosanterolateraiseposteroinferiores.

Resultados: AprevalênciadeachadosdeRMconsistentescomMIFAnessapopulac¸ãofoi de84,8%(95/112).Oânguloalfafoi≥55◦

em77,7%(87/112)dosquadris,enquantooACB apresentoualterac¸õesem10,7%(12/112)dequadris.Observou-seumaaltaprevalênciade achadosqualitativosde RMconsistentescomMIFA,incluindoperdade esfericidadeda cabec¸afemoral(77%),elevac¸ãoóssea(44%),edemafemoral(21%),eosteiteacetabular(9%). Otestedeimpactoanteriorfoipositivoem15%dosquadrisavaliados.

Conclusão: OsexamesdeRMindicaramumaaltaprevalênciadeMIFAentrejogadoresde futeboljuvenil.Nestapopulac¸ão,nãohouvecorrelac¸ãoentreosachadosdoexamefísicoe aevidênciadeMIFAobservadanaRM.

©2017PublicadoporElsevierEditoraLtda.emnomedeSociedadeBrasileirade OrtopediaeTraumatologia.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Femoroacetabularimpingement (FAI) is a condition result-ing from abnormalcontactbetween the femoralhead and theacetabularrim,usuallycausedbyachangein morphol-ogyoftheproximalfemurand/oracetabulum.1–4_Ganzetal.2 described two basic mechanisms of FAI: cam and pincer. Thecammechanismoccursinpatientswithanon-spherical femoralheadorwithadecreasedoffsetbetweentheheadand neckoffemur.Theimpingementareaistypicallylocatedon theanterolateralportionofthefemoralhead–neckjunction. Pincerimpingement,inturn,ischaracterizedbyacetabular overcoveragecausedbyanexcessoftheanteriorwall.1,2,4,5

FAImay decreasethe rangeofmotion(ROM)ofthehip, especially in internal rotation (IR) of the flexed hip.2,6 _FAI isdescribed asacause ofhippainexacerbatedbyphysical activity,andoccursmainlyinyoungadultpatients.4,5_Clinical

symptomsusuallydonotappearuntiladulthood;however, detection ofFAIMisbecomingincreasinglycommon inthe pediatricpopulation.7_{Patientsoftendevelopcartilagelesions} andinjurytotheacetabularlabrum,whichcanprogresstohip osteoarthritis(OA)iftheanatomicchangesarenottreatedor thephysicalactivitymodified.2,8–10

Adolescent patients who practice sports often perform high-impactactivitiesthatrequireextrememovementsofthe hip,whichmaypredisposetomorefrequentandmoreintense conflictsbetweentheproximalfemurandtheacetabulum.11

Physicalactivityduringbonegrowthseemstobeassociated withanincreasedriskofcam-typedeformity.Siebenrocketal. suggestedthatcamimpingementinyoungathletesmaybe relatedtoanabnormalityinthephysealplate.Studiesin high-performanceadolescentbasketballandhockeyplayersfound ahighincidenceofcamtypeFAI.3,12

soccerplayersasdiagnosedbymagneticresonanceimaging (MRI)findings.Patientsalsounderwentaclinicalevaluation ofthehip jointstoascertainpossiblecorrelations between changesonMRIandclinicalsignsofFAI.

Materials

and

methods

Demographics

FromJuly2012toJuly2013,56athletesfromafirst-division Brazilianyouthsoccer teamwere selectedtoparticipatein thestudy.Theypracticesoccerincompetitionlevel,training amean offivehours perday.All athleteswere aged13–18 yearsanddidnothaveanysymptomsofhippathology.The dominantsideofeachathletewasidentified.Theexclusion criteriaforthisstudywereanyhistoryoftreatmentforpain relatedtothehipjointandcontraindicationsorintoleranceto MRI.

Writteninformedconsentwasobtainedfromallathletes andfromtheparentsorguardiansofathletesunder18years old.Theinformed consentformwasapprovedbythe local institutionalreviewboard.

Magneticresonanceimagingevaluation

MRIwas performedin a1.5-T scannerusing the following parameters:panoramicT1coronalsequencesincludingboth hips(echotimesof10–14msandrepeattimesbetween400 and600ms)andT2(echotimesof35–70msandrepeattimes between2000and 3500ms),withaslicethicknessof5mm and512×256linematrixwithafieldofviewof33–36cm;T2 sequencesfocusedonthehipjoints,withandwithoutfat sat-urationinthecoronal,sagittal,andobliqueaxialslices,with athicknessof4mmanda384×224linematrixwithafieldof viewof22–25cm.

Based on the radiographic appearance of the capital femoralphysisonMRI,participantswerestratifiedintothose withopenphysealplatesandthosewithclosedphysealplates. Cammorphologywasevaluatedbymeasuringthealpha angleandfemoralhead–neckoffset.Thealphaanglewas mea-suredonanobliqueaxialsequence asdescribedelsewhere intheliterature.Participantswithanalphaangle≥55◦_were diagnosedwithcammorphology13,14_(Fig.1).

Thefemoralhead–neckoffsetwasmeasuredbydrawinga lineinthecenterofthefemoralheadandneckandtwoparallel lines,onealongtheanteriorcortexofthefemoralneckandthe otheralongtheanteriorouterpartofthefemoralhead.The distancebetweenthesecondandthirdlinescorrespondsto thehead–neckoffset,and,whenlessthan7mm,isindicative ofcamdeformity15_(Fig.2).

Thediagnosis ofpincer morphology was establishedby measuringthecenter-edgeangle(CEA),orWibergangle,and theacetabularindex(AI),orTönnisangle.ACEA≥39◦ _orAI ≤0◦_{indicatespincerdeformity.TheCEAwasmeasuredonthe} coronalplane,betweenaverticallinepassingthroughthe cen-terofthefemoralheadandanotherlinedrawnfromthecenter ofthefemoralheadtothe lateralacetabularrim.TheAIis definedastheanglebetweenahorizontallineandanother lineconnectingthemedialpointofthescleroticzoneofthe

Fig.1–MRIoftherighthip(axialobliqueview)for measurementofthealphaangle.Imagerepresentativeof alteredalphaangle.

Fig.2–Femoralhead–neckoffset<7mmindicatescam deformity.

acetabularroofand the lateral edgeoftheacetabulum16,17 (Fig.3).

Other MRIalterations consistentwithFAIconsideredby the examiningradiologists were osseous bump,18 _synovial pit,6,7,14,19–22 _{bone edema in the femoral neck, acetabular} osteitisandlesionsofthelabrumand/oracetabularcartilage.

Physicalexamination

Fig.3–CEAandtheAIindicativeofpincerdeformity.

anterolateralandposteroinferiorimpingementwerealso per-formed.

Theanteriorimpingementtest wasperformed withthe patientinthesupineposition,flexingthehip90◦_,with adduc-tionandinternalrotation.Thetestwasconsideredpositiveif itelicitedpain.2,6

Theposteroinferiorimpingementtestwasperformedwith thepatientinthesupineposition,hangingthelegoverthe end of the bed while in extension and external rotation. Again,thetestwasconsideredpositiveifthepatientreported pain.20,23

Statisticalanalysis

Two independent musculoskeletal radiologists, blinded to physicalexaminationfindings,analyzedtheMRIscans. Con-cordancebetweentheirresultswasassessedusingthekappa index,whichisconsideredsatisfactorywhen>0.7.Incaseof discrepancybetweenexaminers,athird,experienced radiolo-gistconductedanotherevaluation.

Theresultswere entered into aMicrosoft Excel spread-sheet and exported to PASW Statistics, version 18.0, for analysis. Quantitative variables were described as means andstandarddeviations,andcategoricalvariables,as abso-lute and relative frequencies. Prevalence was reported with95% confidence intervals. Comparisonsofcontinuous variables were performed using the independent samples

t-test.

Table1–Distributionofpatientsbyage.

Age n %

13 7 12.5

14 15 26.8

15 10 17.9

16 11 19.6

17 7 12.5

18 6 10.7

Total 56 100.0

Table2–PrevalenceofMRIfindingsindicativeof femoroacetabularimpingementmorphologyinthe sample(n=56,112hips).

MRIfinding Prevalence(%) 95%CI

Lossofsphericity 73 65–82

Decreasedhead–neckoffset 57 48–66

Alphaangle≥55◦ _{77.7 69.8–85.5}

Acetabularindex≤0◦ _{0 0}

Wibergangle≥39◦ _{10.7 4.9–16.5}

Osseousbump 44 34–53

Sinovialpit 4 0–7

BMEathead/neckjunction 21 14–29

Labrallesion 8 3–13

Degenerativelabrallesion 2 −1to4

Acetabularosteitis 9 4–14

Chondrallesion 3 0–6

BME,bonemarrowedema;CI,confidenceinterval;MRI,magnetic resonanceimaging.

Results

Baselinedemographics

Atotal of56male athletes(112hips)were included inthe study. Noathletes were excluded. Themean age was 15.3 years,withadistributionasshowninTable1.Therightside wasdominantin80.3%(45/56)oftheathletes.Therewasno significantdifferenceintheprevalenceofFAIMoncomparison ofthedominantandcontralateralhips.

MRIfindings

Concordance between the findings of the two examining radiologists was satisfactory; therefore, analysis bya third radiologistwasnotnecessary.Thebestinter-rater concord-ancewasinthealphaangle,withakappacoefficientof0.91.

TheprevalenceofabnormalitiescharacteristicofFAIMwas 84.8%(95/112)(95%CI78–91.5%).TheMRIchangesobserved, andtheirrespectiveprevalence,aredescribedinTable2.

Abnormalalphaangle(≥55◦_{)wasobservedin77.7%(87/112)} ofhips,whileabnormalfemoralhead–neckoffset(<7mm)was seenin57%(64/112).Thealphaanglewasalteredinall indi-viduals withreduced offset.Thephysealplatewasopenin 23.2%(13/56)ofathletes.Therewasnosignificantdifference intheprevalenceofalteredalphaanglebetweenathleteswith anopenphysealplateandthosewithaclosedphysealplate.

Table3–NumberofMRIchangesfoundinthesample (n=56,112hips).

Numberof changes

Frequency Percentage Cumulative percentage

0 17 15.2 15.2

1 9 8.0 23.2

2 8 7.1 30.4

3 20 17.9 48.2

4 24 21.4 69.6

5 19 17.0 86.6

6 11 9.8 96.4

7 2 1.8 98.2

8 2 1.8 100.0

Total 112 100.0

Table4–Resultsofrangeofmotion(ROM)testsin patientswithandwithoutMRIevidenceof femoroacetabularimpingementmorphology.

Variable MRIevidence ofFAIM

NoMRI evidenceof

FAIM

p

Flexion 127.9±5.6 126.5±7.8 0.48

Extension 9.9±1.5 10.6±1.7 0.12

Adduction 32±4.5 31.5±3.4 0.64

Abduction 47.4±4.4 48.5±3.8 0.31

IR 43±11.2 46.8±10.7 0.2

ER 49.3±8.2 48.2±4.6 0.43

ER,externalrotation;FAI,femoroacetabularimpingement;IR, inter-nalrotation;MRI,magneticresonanceimaging.

Resultsexpressedasmean±standarddeviation.p-valuesfrom Stu-dent’st-testforindependentsamples.

100%(6/6)in18-year-olds. Therewere nosignificant differ-encesinprevalenceacrossdifferentages.

Areasofbonemarrowedema(BME)wereobservedinthe femoral head–neckjunction of24 hips (21%), all ofwhich exhibitedanelevatedalphaangle.Acetabularlabrallesions wereidentifiedin10hipsandchondrallesionswerefoundin three.

All hips had an AI ≥2◦_{. A CEA >39}◦ _{was seen in10.7%} (12/112)ofthehips,indicatingadiagnosisofpincerdeformity. PooledanalysisofMRIfindings(Table3)showedthatmost ofthehips(76.8%)hadmorethanonealterationsuggestiveof FAI,and>50%hadfourormoresuchchanges.

CorrelationbetweenMRIandphysicalexamination

findings

TheresultsofROMmeasurementarepresentedinTable4. TherewasnosignificantassociationbetweenROMandMRI findingsconsistentwithFAI.Concerningtheposteroinferior andanterolateralimpingementtests,theformer was nega-tiveinallathletes, whilethelatterwaspositivein17hips, ofwhich15showedfindingssuggestiveofFAIonMRIscans. Therewasnosignificantdifferenceintheprevalenceof posi-tiveimpingementtestresultsbetweenhipswithandwithout signsofFAI.Evenwhenanalphaangle≥65◦_{wasconsidered} diagnosticofcam-typeimpingement,therewasnocorrelation betweenalphaangleandpositiveanterolateralimpingement

test.TherewasnocorrelationbetweenMRIchangesand phys-icalexaminationfindings.

Discussion

Physicalactivityduringbonegrowthmaybeassociatedwith anincreasedriskofFAIdeformity,whichcanprogresstohip OAduringadulthood.Thisisthefirststudytoassessthe preva-lenceofMRIchangesconsistentwithFAIMinasymptomatic youth soccer players and analyze the potential correlation betweenthesechangesandphysicalexaminationfindings.

The prevalence of MRI changes indicative of FAIM in the present samplewas84.8%.This isahigherprevalence thanthatreportedinpreviousstudiesofsoccerplayers.24–26 Whencomparingtheprevalenceofpathologicalalphaangle only(≥55◦_{,cam-typedeformity),the77.7%ratefoundinthe} present study was higher than those reported byGerhardt et al.25 _{(68%) and Johnsonet al.}26 _{(60%), both studies that} evaluatedadultsoccerplayersusingplainradiography.Itwas also higher than the 26% prevalence reported by Agricola et al. who evaluated adolescent soccer players using plain radiography,butconsideringthealphaangleabnormalonly if>60◦_.24–26 _{Thiscanbeexplainedbythegreatersensitivity} ofMRIcomparedtoplainradiographyinidentifyingchanges thatcharacterizeFAI.27–29_{Theexcellentconcordancebetween} theexaminingradiologistsinmeasuringthealphaangle,with akappacoefficientof0.91,demonstratesthereproducibilityof MRIfordiagnosisofcam-typeimpingement.

MRIfindingsofcamdeformityinthepresentsamplewere verysimilartothosereportedinpreviousstudiesofadolescent athletesinothersports.Siebenrocketal.30_{reportedan89%} prevalenceofcamdeformityinbasketballplayersaged9–25 years,includingafterphysealclosure.Philipponetal.found analphaangle≥55◦_{in75%ofhockeyplayersbetweentheages} of10and18.21

Comparingtheprevalenceofcamdeformityinthepresent studywiththeresultsofFranketal.31_{inasystematicreview} aboutprevalenceofFAIMinasymptomaticvolunteers,itwas higherthanthe37–54.8%foundinathletesandmuchhigher thanthe23.1%inthegeneralpopulation.

A high prevalence of cam-type impingement morphol-ogyinyounghigh-levelathletescorroboratesthehypothesis proposedbySiebenrocketal.,12_{whichsuggestsadirect} rela-tionshipbetweenphysicalactivityandahigherincidenceof cam-typeFAIM,probablyduetoenlargementofthephyseal plate. The finding ofMRI evidence ofBME in the femoral head/neckjunction in21.4%ofhips(24/112)inthissample ishighlysuggestiveofstress-relatedchanges,whichsuggest activeFAIandprobablyprecedethedevelopmentoffemoral head–neckbumpdeformity.

Theprevalenceofcamdeformitywassimilarbetween ath-leteswithopenandclosedphysealplates,whichsuggestthat thecamisformedevenbeforephysealplategrowthis com-pleted.Ifthislesioniscausedbystressfromboneimpaction, theearlieritstarts,thegreaterthepotentialfordamage;the immature skeletonis more complacent, and can easilybe remodeledbyabnormalforces.

activ-ityormovementthatcausesFAI.Simplestressoverthephysis duringphysicalactivitiescouldexplainthehighprevalenceof cam-typeimpingementmorphology.

TheidentificationoftwoormoreMRIchangesindicative ofFAIin 76.8% ofhips, inan entirely asymptomatic sam-ple,underlinesthe importanceofcarefulassessmentwhen recommendingsurgicalprocedurestopatientsinwhom diag-nosisisbasedsolelyonMRIfindings.Monitoringofathletes couldhelpdefinehowmanyofthesepatientswoulddevelop symptomsandrequiresurgery.Follow-upofthepresent sam-plewouldallowidentificationtheincidenceofchondraland labrallesionsinyouthsoccerplayers,aswellasidentification ofwhichlevelofsportspracticeintensitycouldbeconsidered ariskfactorforhipOA.

When athleteswithsigns ofimpingementon MRIwere comparedtothosewithnormalhips,nosignificantdifferences inROMoranterolateralandposteroinferiorimpingementtest resultswerefound.Thissuggeststhat,inasymptomaticyouth soccerplayers,physicalexaminationfindingsareinconclusive regardingthediagnosisofFAI.Furthermore,itsuggeststhat MRIcanrevealabnormalitiesconsistentwithFAIMbeforethey becomeapparentonclinicalexamination.

The inverse relationship between increased prevalence ofFAI and reduced IR described in the literaturewas not confirmed inthis study, probably because the samplewas asymptomaticandveryyoung(i.e.,asubclinicalpopulation).32 Any decrease in IR or ER could be important, because of thepossibilityofincreasedriskofanteriorcruciateligament rupture.33

Limitations

Thelimitationsofthisstudyincludethelackofacontrolgroup ofadolescents who didnotpracticephysicalactivitiesata highlevel.Weplantoconductamatchedcase–controlstudy toevaluatetheprevalenceofthesefindingsinanormal pop-ulation.Inaddition,theagerangeoftheathletescouldhave beenextendeddownto10years,whichwouldhaveallowed betterassessmentofthetimingofFAIMonset,especiallyof cam-typeFAI.

Conclusion

Theyouthsoccerplayerswhoparticipatedinourstudyhad ahighprevalenceofabnormalitiescharacteristicofFAIMon MRI.Physical examinationfindingsdid notcorrelated with MRIevidenceofFAIM.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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