w w w . r b o . o r g . b r
Original
article
Evaluation
of
the
anterolateral
ligament
of
the
knee
by
means
of
magnetic
resonance
examination
夽
Camilo
Partezani
Helito
∗,
Marco
Kawamura
Demange,
Paulo
Victor
Partezani
Helito,
Hugo
Pereira
Costa,
Marcelo
Batista
Bonadio,
Jose
Ricardo
Pecora,
Marcelo
Bordalo
Rodrigues,
Gilberto
Luis
Camanho
InstituteofOrthopedicsandTraumatology,HospitaldasClínicas,SchoolofMedicine,UniversidadedeSãoPaulo,SãoPaulo,SP,Brazil
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Articlehistory:
Received17January2014 Accepted7March2014 Availableonline7April2015
Keywords: Knee
Jointinstability
Magneticresonanceimaging Anatomy
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Objective:Toevaluatethepresenceoftheanterolateralligament(ALL)ofthekneein mag-neticresonanceimaging(MRI)examinations.
Methods:Thirty-threeMRIexaminationsonpatients’kneesthatweredonebecauseof indi-cationsunrelatedtoligamentinstabilityortraumawereevaluated.T1-weightedimagesin thesagittalplaneandT2-weightedimageswithfatsaturationintheaxial,sagittaland coro-nalplaneswereobtained.Theimageswereevaluatedbytworadiologistswithexperience ofmusculoskeletalpathologicalconditions.Inassessingligamentvisibility,wedividedthe analysisintothreeportionsoftheligament:fromitsorigininthefemurtoitspointof bifur-cation;fromthebifurcationtothemeniscalinsertion;andfromthebifurcationtothetibial insertion.Thecapacitytoviewtheligamentineachofitsportionsandoverallwastakento beadichotomouscategoricalvariable(yesorno).
Results:TheALLwasviewedwithsignalcharacteristicssimilartothoseoftheotherligament structuresoftheknee,withT2hyposignalwithfatsaturation.Themainplaneinwhich theligamentwasviewedwasthecoronalplane.Someportionoftheligamentwasviewed clearlyin27knees(81.8%).Themeniscalportionwasevidentin25knees(75.7%),thefemoral portionin23(69.6%)andthetibialportionin13(39.3%).Thethreeportionswereviewed togetherin11knees(33.3%).
Conclusion:Theanterolateralligamentofthekneeisbestviewedinsequencesinthe coro-nalplane.Theligamentwascompletelycharacterizedin33.3%ofthecases.Themeniscal portionwasthepartmosteasilyidentifiedandthetibialportionwasthepartleast encoun-tered.
©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.
夽
WorkdevelopedintheMedicalInvestigationLaboratoryfortheMusculoskeletalSystem(LIM41),DepartmentofOrthopedicsand Traumatology,SchoolofMedicine,UniversidadedeSãoPaulo,SãoPaulo,SP,Brazil.
∗ Correspondingauthor.
E-mail:[email protected](C.P.Helito).
http://dx.doi.org/10.1016/j.rboe.2015.03.009
Avaliac¸ão
do
ligamento
anterolateral
do
joelho
por
meio
de
exame
de
ressonância
magnética
Palavraschave: Joelho
Instabilidadearticular Imagemporressonância magnética
Anatomia
r
e
s
u
m
o
Objetivo: Avaliara presenc¸a doligamentoanterolateral(LAL)dojoelhoem exames de ressonânciamagnética(RM).
Métodos: Foramavaliadas33 RMdejoelhode pacientesfeitas porindicac¸õesnão rela-cionadasainstabilidadeligamentaroutrauma.Foramobtidasimagensnoplanosagital ponderadasemT1eimagensnosplanosaxial,sagitalecoronalponderadasemT2com saturac¸ãodegordura.Asimagensforamavaliadaspordoisradiologistasexperientesem patologiasmusculoesqueléticas.Naavaliac¸ãodavisualizac¸ão,dividimosaanálisedo lig-amento em trêsporc¸ões:origemfemoralaté oseuponto debifurcac¸ão, da bifurcac¸ão atéainserc¸ãomeniscaledabifurcac¸ãoatéainserc¸ãotibial.Considerou-secomvariável categóricadicotômica(simounão)acapacidadedevisualizaroligamentoemcadauma dasporc¸õesenoseutodo.
Resultados: OLALfoivisualizadocomcaracterísticadesinalsemelhanteàsdemais estru-turasligamentaresdojoelho,comhipossinalemT2comsaturac¸ãodegordura.Oprincipal planoemqueoligamentofoiidentificadofoiocoronal.Algumaporc¸ãodoligamentofoi visualizadacomclarezaem 27(81,8%)joelhos.Aporc¸ãomeniscalficouevidenteem25 (75,7%)dosjoelhos,aporc¸ãofemoralem23(69,6%)eatibialem13(39,3%).Astrêsporc¸ões foramvisualizadasemconjuntoem11(33,3%)joelhos.
Conclusão: Oligamentoanterolateraldojoelhoémaisbemvisualizadoemsequênciasno planocoronal.Oligamentofoicaracterizadoporcompletoem33,3%doscasos.Aporc¸ão meniscalfoiamaisfacilmenteidentificadaeatibialamenosencontrada.
©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.
Introduction
Theanterolateralligament(ALL)ofthekneewasmentioned intheorthopedicliteratureforthefirsttimebySegondin1879 withVincentetal.1Althoughitwasdescribedmorethan120 yearsago,thisligamentwasnamedrecentlybyVieiraetal.2 inastudyontheiliotibialtract.Subsequently,startingin2012, someanatomicalstudiescameout,withtheobjectiveof defin-ingparametersfortheoriginandinsertionoftheALL,itspath andotherparticularfeatures.1,3–5
Recentstudies havedemonstratedthattheorigin ofthe ALLisanterioranddistaltotheoriginofthelateralcollateral ligament(LCL).TheALLislocatedbetweentheLCLandthe tendonofthepoplitealmuscle,inthelateralfemoralcondyle. Ithas an oblique path toward the tibia, with two distinct insertions:oneinthelateralmeniscusandtheotherinthe proximaltibia,betweenGerdy’stubercleandtheheadofthe fibula.5
Weber cited some aspects ofthe ALL in a study using magneticresonanceimaging(MRI)oftheknee.Thisauthor reportedthatitslengthvariedfrom4.2cminflexionto3.9cm inextension,whichsuggeststhatitisundergreatertension inflexion.6Claesetal.7evaluated350MRIscansonanterior cruciateligament(ACL)injuries,searchingforvisualizationof theALL,andreportedhavingviewedthisstructurein95.7%of thecases.
Recently,greaterimportancehasbeenplacedonthis lig-ament.Therehavebeensuggestionsthatthisstructuremay presentanassociationwithACLinjuriesandwiththegenesis
ofanterolateralkneeinstability.1,3–5,8Thus,studiesinwhich theALLisidentifiedbymeansofimagingexaminationshave becomenecessary.
Theaimofthepresentstudywastoevaluatethepresence oftheALLinkneeMRIexaminations.Asasecondaryobjective, theaimwastoassesswhatthebestorientationforviewingthe ALLwouldbe.
Materials
and
methods
Thirty-threeMRIscansonthekneesofpatientswho under-wenttheexaminationduetoclinicalindicationsunrelatedto kneeligamentstabilityortraumawereevaluatedwithregard tolesionsofthepatellarcartilage.Noneofthepatients pre-sented any ligament lesions,meniscal lesions or chondral lesionsinlocationsotherthanthepatella.Thepatients’mean agewas32.5±8.1years(rangingfrom21to49).Sevenpatients weremaleand26werefemale.
Theexaminationswere performed inamachine witha 1.5-Teslamagneticfield(SigmaHDxT,GeneralElectricMedical Systems,Milwaukee,Wisconsin,USA),usinganeight-channel knee coil (HD TR knee array). T1-weighted images were obtainedinthesagittalplane(TR/TE,400–700/9–16)and T2-weightedimageswithfatsaturationintheaxial,sagittaland coronalplanes(TR/TE,3200–4500/40–50),withslicethickness of3mmandspacingof0.5mm.
FEM
A
B
C
TIB
2 2
2 1
1
1
3 3
3 P
ML
Fig.1–(A)Schematicdrawing;(B)coronalMRIslice;(C)anatomicalphotooftheALLoftheknee.Inthesethreeimages, arrow1(green)representsthefemoralportion,arrow2(red)themeniscalportionandarrow3(blue)thetibialportion.P, tendonofthepoplitealmuscle;FEM,lateralfemoralcondyle;TIB,lateraltibialplateau.(Forinterpretationofthereferences tocolorinthisfigurelegend,thereaderisreferredtothewebversionofthearticle.)
evaluations with a minimum interval of 30 days between them.Intheeventoflackofagreementintheevaluations,two otherevaluatorsviewedtheMRIscanstodeterminewhether thestructurewaspresentornot.
InevaluatingtheviewsoftheALL,wedividedthe analy-sisintothreeportionsoftheligament:5(1)fromthefemoral origintothepointofbifurcation;(2)fromthebifurcationto themeniscalinsertion;and(3)fromthebifurcationtothe tib-ialinsertion(Fig.1).Fordidacticpurposes,theseportionsare calledthefemoral,meniscalandtibialportionshere.
Thecapacitytoviewtheligamentineachoftheportions andinitsentiretywasconsideredtobeadichotomous cate-goricalvariable(yesorno).
Results
TheALLwasviewedonthekneeMRIscansasathinlinear structure,withanoutlinethat sometimeswasregular and sometimeswasundulating.Itpresentedsignalcharacteristics similartothoseoftheotherligamentstructuresoftheknee, withhyposignalseenonT2imageswithfatsaturation.
Themainplaneinwhichtheligamentwasidentifiedwas the coronalplane.Thefemoral portionwas identifiedas a structure with its origin close to the anterior limit of the originoftheLCL,withaninferiorpaththatwaspractically verticalandsuperficialtothepoplitealtendon,with bifurca-tionlessthan0.5cmfromthecorpusofthelateralmeniscus. Themeniscalportionoftheligamentpresentedan anteroin-ferioroblique pathfromthebifurcationtowardtheanterior corpus–cornutransitionofthe meniscus,viewed on subse-quentcoronalslices.Thetibialportionwasbestcharacterized immediatelyafterthebifurcation,withalateraland practi-cally verticalpath. Itmaintainedproximitytothe iliotibial
Table1–Numberofviewsandpercentageviewingof eachportionoftheALLofthekneeseparatelyandofall oftheportionstogether,in33MRIexaminations.
Numberofviews Percentage(%)
Femoralportion 23 69.6%
Meniscalportion 25 75.7%
Tibialportion 13 39.3%
Anyportionoftheligament 27 81.8%
Entireligament 11 33.3%
tract,withitsinsertionslightlyposteriorlytoGerdy’stubercle (Fig.2).
The characterization of the ligament in the sequences acquiredintheaxialandsagittalplaneswaslimited.These sequenceswereusedforconfirmingthelocationoftheALL, basedonparametersfromanatomicalstudies(Fig.3).
From analyzing the MRIexaminations,it was seen that someportionoftheligamentcouldbeclearlyviewedin27 knees(81.8%).Inthese,themeniscalportionoftheligament was theonemostfrequentlyviewed,observedin25 knees (75.7%).Thefemoralportionwasobservedin23knees(69.6%) andthetibialportionin13(39.3%).Thethreeportionstogether wereviewedin11knees(33.3%)(Table1).
Infourcases,therewasdisagreementbetweenthe evalua-torsregardingthepresenceoftheALLstructure:tworegarding thefemoralportionandtworegardingthemeniscalportion. Inthesecases,twoauxiliaryevaluatorsmadecomplementary assessmentsandconfirmeditspresence.
Discussion
Fig.2–T2-weightedcoronalMRIslicewithfatsaturationshowing:(A)femoralportion;(B)meniscalportion;and(C)tibial portionoftheALLoftheknee.
Fig.3–T2-weightedMRIsliceswithfatsaturation:(A) coronalsliceshowingALLoftheknee;(B)sagittalsliceand (C)axialsliceshowingthetopographiclocationofthe ligamentbasedonanatomicalparameters.
this structure,they didnotdescribeany detailed anatomi-calparametersforit.Itsorigininthelateralcondyleandits two insertionshave beenclearly identifiedin the kneesof cadavers.1,4,5Itsbifurcationpointandmeniscalinsertionwere mostclearlydemonstratedinthestudiesbyHelitoetal.3and Claesetal.5
This structure may have importance in the genesis of anterolateralinstabilityoftheknee. Theimportanceofthis jointcapsuleregioninrotationalinstabilityhasbeenshown inbiomechanicalstudies,althoughthesedidnotfocus specif-icallyontheALL.8
Even though thesestudies suggestedthat injuryto this ligamentwouldincreasetheanterolateralinstabilityand con-sequentlythegradeinthepivot-shifttest(whichisconsidered tobethemainpredictoroffunctionalresultsfollowingACL reconstruction),therearestillnotmanystudies demonstrat-ingthepossibilityofviewingthisstructurethroughtheMRI protocolsgenerallyused,i.e.inT2-weightedsequenceswith fat saturation and T1-weightedsequencers,in thesagittal, coronalandaxialplanes.6,9
OurstudyshowedthatitwasnotpossibletoviewtheALL inall the kneeswhen MRIwasperformedwiththe above-mentioned sequences,especiallywithregard toviewingall itsportions.
Weconsiderthatitisimportanttocompletely character-izetheALL,i.e.itsentirestructureinasingleexamination,so astomakeanimagingevaluationofthisstructureincasesof suspectedinjury.Furthermore,understandingthelimitations onviewingtheentireligamentinMRIexaminationsmakesit possibletobetterdeterminethepredictivevalueofthistest foridentifyinginjuries.Failuretoview theligamentcanbe attributedtoinjuryorsimplythelimitationsofMRI evalua-tions.
ThestudybyClaesetal.7didnotmentiontheparameters usedinMRIorthedifferentiationbetweentheligament por-tionsthatwereevaluated.However,webelievethatbecause ofjointtensioningduetohemarthrosisoftheACLinjury,its viewingmayhavebeengreater.
Inastudyusingthree-dimensionalMRI,Carpentershowed thatkneesthathadundergoneACLreconstructionpresented greaterinternalrotation ingoing fromextensiontoflexion thandidkneeswithanativeACL.Thissituationshowedthat thisreconstructionalonedidnotfullyrestorethekinematics oftheknee.Thegreaterinternalrotationinflexionmayhave beenduetoanundiagnosedanduntreatedALLinjury.10,11
Becausetheepicondylarregionisthepointoforiginofthe ALLandLCLandthepointofinsertionofthetendonofthe poplitealmuscle,itisnotalwaysfeasibletoclearly differen-tiatethethreestructuresusing1.5-TeslaMRImachines.This makesitdifficulttointerpretpossibleinjuriesinthisregion. Thesameisseeninrelationtothetibialinsertion,atwhich theremaybesuperpositionofthejointcapsuleortheiliotibial tract.Atthesiteofthemeniscalinsertion,thissuperposition doesnotoccurandthereforeviewingtheinsertionoftheALL inthisregioniseasier.
Characterizationofthisstructureisimportantforfuture studies, given that ALL injury may be responsible for the portion ofthe casesthat donot evolve satisfactorily after ACL reconstruction.12–14 Althoughreconstruction failure in situationswithouttechnicalerrorsoftunnelpositioningand withgraftsofappropriatesizearecreditedasgraftfailures, webelievethattheALLmayhaveasignificantroleinthese patients.
OnelimitationofthepresentstudyisthefactthattheMRI wasperformedonpatientswithoutacutekneetraumaand thereforewithsmallvolumesofjointfluid.Sincelarger quan-titiesoffluidinsidethejointputstensiononthecapsuleand makesit easiertoview the ALL,better viewingoftheALL mightbeachievedinexaminationsonpost-traumacases.For futurestudies,wesuggestthatMRIexaminationsonknees shouldbeperformedafterinjectingfluidinordertoput ten-siononthecapsule,orthatpatientswithacutekneetrauma shouldbeevaluated.Another limitationtobeconsideredis the1.5-TeslaMRImachine,whichmightnotbesufficientfor clearevaluationofthestructureandforenabling differentia-tioninrelationtoadjacentstructures.Nevertheless,sincethis machineistheonemostusedinroutineclinicalpracticeinour setting,weconsiderthatitwasadequateforuseinthepresent study.
Giventhatweonlyhadtorequest evaluationsfrom two complementaryevaluatorsinfourcases,webelievethatthe evaluationbiaswasverylowanddidnotchangethenatureof thefindings.Becauseevaluationsonthisligamentbymeansof MRIexaminationsareatanearlystage,itispossiblethatthese disagreementsintheevaluationsmightnotoccur infuture studies,becauseofthegreaterexperienceoftheevaluators.
Becauseofthelowviewingratefoundforthethree por-tionsoftheligamentinthethreeacquisitionplanes,withthe weightingsgenerallyusedinMRI,webelievethatitisdifficult to establish diagnostic protocols with this type of exami-nation.Furtherstudiesneedtobeconductedusingthinner slices,differentsequences and machines withbigger mag-netic fields (3T),in anattempt toview thisstructure with
greaterclarity.Studiesusingobliqueslices,thinnerslicesand different weightings are already underwayinour clinic,in ordertocharacterizetheligamentmoredefinitivelyand com-pletely.
Conclusion
TheALLoftheknee wasbestviewed inMRIexaminations throughsequences acquiredinthecoronalplane.The liga-mentwascompletelycharacterizedonlyin33.3%ofthecases. Themeniscalportionwasmosteasilyidentifiedandthetibial wasfoundleastofteninoursample.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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