Rev. bras. ortop. vol.50 número1

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

Review

article

Partial

tearing

of

the

anterior

cruciate

ligament:

diagnosis

and

treatment

Eduardo

Frois

Temponi

,

Lúcio

Honório

de

Carvalho

Júnior

,

Bertrand

Sonnery-Cottet

_,

_Pierre

_Chambat

a_{HospitalMadreTeresa,BeloHorizonte,MG,Brazil}

b_{SantyOrthopedicsCenter,HôpitalJeanMermoz,Lyon,France}

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Articlehistory:

Received25March2014 Accepted15April2014

Availableonline14February2015

Keywords:

Anteriorcruciateligament/injuries Anteriorcruciateligament/surgery Knee

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b

s

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t

Partialtearsoftheanteriorcruciateligament(ACL)arecommonandrepresent10–27%ofthe total.Themainreasonsforattendingtocasesofnon-tornbundlesarebiomechanical, vas-cularandproprioceptive.Continuedpresenceofthebundlealsoservesasprotectionduring thehealingprocess.Thereiscontroversyregardingthedefinitionoftheseinjuries,which isbasedonanatomy,clinicalexamination,translationmeasurements,imaging examina-tionsandarthroscopy.Thewayinwhichitistreatedwilldependontheexistinglaxityand instability.Conservativetreatmentisoptionalforcaseswithoutinstability,withafocuson motorrehabilitation.Surgicaltreatmentisachallenge,sinceitrequirescorrectpositioning ofthebonetunnelsandconservationoftheremnantsofthetornbundle.Thepivotshift testunderanesthesia,themagneticresonancefindings,thepreviouslevelandtypeofsports activityandthearthroscopicappearanceandmechanicalpropertiesoftheremnantswill aidtheorthopedistinthedecision-makingprocessbetweenconservativetreatment, surgi-caltreatmentwithstrengtheningofthenativeACL(selectivereconstruction)andclassical (anatomical)reconstruction.

©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

Lesão

parcial

do

ligamento

cruzado

anterior:

diagnóstico

e

tratamento

Palavras-chave:

Ligamentocruzadoanterior/lesões Ligamentocruzadoanterior/cirurgia Joelho

r

e

s

u

m

o

Lesõesparciaisdoligamentocruzadoanterior(LCA)sãocomunserepresentam10–27%das totais.Asprincipaisrazõesparaatenc¸ãoaofeixenãorompidosãobiomecânicas,vasculares eproprioceptivas.Apermanênciadofeixeserveaindadeprotec¸ãoduranteoprocesso cica-tricial.Adefinic¸ãodessalesãoécontroversa,baseadanaanatomia,noexameclínico,na medidadatranslac¸ão,nosexamesdeimagemenaartroscopia.Seutratamentovaidepender dafrouxidãoedainstabilidadeexistentes.Otratamentoconservadoréopcionalparacasos

∗ _{Correspondingauthor.}

E-mails:[email protected],[email protected](E.F.Temponi). http://dx.doi.org/10.1016/j.rboe.2015.02.003

seminstabilidade,comenfoquenareabilitac¸ãomotora.Otratamentocirúrgicoédesafiador, poisexigecorretoposicionamentodostúneisósseoseconservac¸ãodosremanescentesdo feixerompido.Otestedopivot-shiftsobanestesia,osachadosàressonânciamagnética,o níveleotipodeatividadeesportivapréviaeoaspectoartroscópicodosremanescentesesuas propriedadesmecânicasauxiliarãooortopedistanoprocessodecisórioentreotratamento conservador,otratamentocirúrgicocomreforc¸odoLCAnativo(reconstruc¸ãoseletiva)oua reconstruc¸ãoclássica(anatômica).

©2015SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

Over the last 15 years, knowledge of tearing and recon-structionoftheanteriorcruciateligament(ACL)hasevolved considerably. Anatomical studies have made it possible to precisely identify ligament insertions in bones,1,2 _while

biomechanical studies have providedbetter understanding of the function of each of the ligament bundles.2 _Better

anatomicalknowledgeand biologicalinterestinpreserving theremnantsofthetornACLhaveledtomodificationofthe classicalreconstructiontechniques:double-band,anatomical andselectiveforpartialtears.3–7

CompletetearingoftheACLcanbediagnosedthrough clin-icalexamination,8_{whilepartialtearingoftencannot.Insuch}

cases,complementaryexaminationsareneededfor confirma-tion.ThedefinitivediagnosisofapartialACLtearisreachedby combiningclinicalfindings,imagingexaminationsand,when necessary,arthroscopicfindings.IncasesofpartialACLtears, itisessentialtoassessthecompetenceandfunctionalityof theremainingfiberswithregardtokneestabilization.Italso hastobeascertainedwhether theeventinquestionwas a partialtearorwhethertherewasacompletetearthatisnow healing.7–9

Aconsensusfordefining,diagnosingandtreatingpartial ACL tears is sought. Motivated bythe discussion that still existsinthe literatureandthe needforbetter understand-ing,thepresentreviewhadtheaimofdiscussingpartialACL tears.

Definition

Norwood and Cross apud Colombet et al.9 _{described three}

bands for the ACL that have anatomical and functional importance:anteromedial(AM),posterolateral(PL)and inter-mediate.Othershavedescribedtwobandsthatpresentknown andaccepted functionality.8–11 _{Eachband would contribute}

separatelytowardstabilizingthekneeandcould beinjured separatelyinpartialtears.AccordingtoHongetal.,10_partial

tearswouldbethoseinwhichlessthan50%oftheligamentis torn.Ontheotherhand,accordingtoNoyesetal.,11_the

def-initionofpartialtearswouldberelatedtothepercentageof theACLfibersthataretorn,giventhattearingof50–75%ofthe diameterwouldbehighlycorrelatedwithclinicalfailure.

TheAmerican MedicalAssociation,which divides these injuriesintothreedegreesofseverity,definestraumaticACL tearsasgradeIIwhenthesetearsarepartial:moderatesprains

causedbydirectorindirecttrauma.9_{Theclinicalpresentation}

inthesecaseswouldbecharacterizedbypain,partial func-tionallimitation,hemarthrosisandthepossibilityofepisodes ofinstability.DeFrancoandBach6_putforwarda

multifacto-rial definitionthattookintoconsiderationthe combination ofclinicalandarthroscopicfactors,andotherauthorswould agreewiththis.

IncasesofpartialACLtears,the mostimportant objec-tiveistodeterminewhetheranyremnantfibersarepresent andwhethertheywouldenableclinicalstabilityiftheywere kept.Althougharthroscopicevaluationmakesitpossibleto observe theseremnants, useofthetraditionalportals may giverisetoconfusioninassessingthem.Sonnery-Cottetand Chambat12_{suggestedusinga“figureof4”(Cabot)positionfor}

betterassessmentoftheremnantsofthePLband.Crainetal.,7

Colombet et al.9 _{and Sonnery-Cottetet al.}13 _described

pat-ternsofpartialtears.Amongthecasesevaluated,17%were consideredtopresentgoodclinicalqualityand83%,poor qual-ity.Better-qualitytissuewithpreservedmechanicalproperties was seen morefrequently when the PLband was present (70%),tothedetrimentofintercondylarhealing(27%)or heal-ingofremnantsadheringtotheposteriorcruciateligament (13%).Althoughsomestudieshavedemonstratedclinical sta-bilityassociatedwithpartialtears,Maedaetal.14_didnotfind

greatstabilityinthesecases.

Diagnosis

DiagnosingpartialACLtearsremainsachallenge.Itneedsto bebasedonacombinationofclinicalexaminationand imag-ingexaminations(radiographyandmagneticresonance),with thedefinitivediagnosisreachedthrougharthroscopic assess-ment,whenthisisindicated.

Clinicalexamination

InastudyconductedbytheFrenchSocietyofArthroscopy,15_a

pivotshifttestwithlessrebound(0or+1)wouldcorrespondin 94%ofthecasestopartialtearsoreventoincompletehealing. Studies on cadavers have proven the difficulty in cor-relating the magnitude of the injury and its types with thealterationsseeninclinicaltests.16_{Severalauthors have}

reported that it is possible to observe a hard stop in the Lachman test in cases ofpartial tears.9,16,17 _{The Lachman}

test is more sensitive for diagnosing complete ACL tears, whilethepivotshifttestandjerktestaremorespecific.16–18

Another point to be considered is that the sensitivity of the pivot shift test increases from 24% to 92% when the patientisassessedunderanesthesia,whichisthebest sit-uationforevaluating thefunctional stateofthe remaining fibers.9,19–21_{Whenthistestispositive,itindicatesrotational}

instability,whichisnotevaluatedthroughdifferentialanterior translation tests. In negative cases, the arthroscopic eval-uation makesit possible toassess associated injuriesthat mightcausedifficultyinthetest:meniscallesions,displaced chondral lesions and interposing of the remnants of the ACL.

Measurementofthedifferentialanteriortranslation

Avarietyofdevicesareavailableformeasuringdifferential anteriortranslation.Theonesthatarebestknownandused inclinicalpracticeare theKT 1000®_{, KT2000}®_,Rolimeter®

andTelos®_{devices.Theiruseformakingdiagnosesismore}

accurateincasesofsubacuteandchroniclesionswithbetter paincontrolandabsenceofmusclecontractions.The differ-entialanteriortranslationislessthan3mmin95%ofnormal knees.Incomparative evaluations,whenthistranslation is greaterthan3mminrelationtotheasymptomaticside,90% ofsuchcasespresent ACLtears.Measurementsofbetween 3and5mmmayrepresentpartialtears.17,20,21_Dejouretal.17

describeddifferencesintranslationmeasurementsbetween patientswithcompleteand partialtears.Thepatientswith completetearspresentedameanof9.1±3.4mm,in compari-sonwith5.2±2.9mmamongthosewithpartialtears(p<0.05). Theyalsoobservedthat67%ofthepatientswithpreservation ofthePLbandpresentedadequateremainingclinical func-tion,versus17%ofthoseinwhomtheAMbandwaspresent. Itwasconsideredthatfunctionalityremainedwhenthepivot shifttestresultwas0or+1andwhenthedifferential ante-riortranslationwaslessthan4mm.Itneedstobebornein mindthatthesedevicesonlyevaluatethedifferential ante-riortranslation,withoutanyrotationalevaluation.Theiruse inassociationwiththeothertestsandimagingexaminations isfundamentalformakingthediagnosisanddefiningthe ther-apy.

Imaging

examinations

Radiology

Radiological evaluation performed together with measure-mentsofthedifferentialanteriortranslationhasbeenshown tobeimportantfordiagnosingACLinjuries.Inlateral radio-graphswithanteriorizationofthetibiathatareproducedon individualswithcompletetears,significanttranslationofthe

Source: Dr. Guilherme Reis, Image Bank of the Imaging Diagnostics Center, Hospital Madre Teresa, Belo Horizonte, MG, Brazil

Fig.1–Magneticresonanceimagingofpartialtearsofthe anteriorcruciateligamentoftheknee.(A)Injurytothe posterolateralbandandpreservationoftheanteromedial band;(B)injurytotheanteromedialbandandpreservation oftheposterolateralband.

Source_{:Dr.GuilhermeReis,ImageBankoftheImaging}

DiagnosticsCenter,HospitalMadreTeresa,BeloHorizonte, MG,Brazil.

medialandlateralcompartmentscanbeseen,whileinthose withpartialtears,littletranslationisseeninrelationtothe normalside.9,22

Magneticresonance

Source: Dr. Bertrand Sonnery-Cottet, Santy Orthopedics Center, Lyon, France

Posterolateral fiber

Anteromedial fiber

B

A

Anteromedial remaining fiber

Posterolateral remaining fiber

Fig.2–Arthroscopicviewofpartialtearsoftheanteriorcruciateligamentoftheknee.(A)Injurytotheanteromedialband andpreservationoftheposterolateralband;(B)injurytotheposterolateralbandandpreservationoftheanteromedialband.

Source_{:Dr.BertrandSonnery-Cottet,SantyOrthopedicsCenter,Lyon,France;Posterolateralfiber;Anteromedialremaining}

fiber;Posterolateralremainingfiber;Anteromedialfiber.

without the capacity toconfirm this or makea functional assessmentontheremainingportions.21–23_{Specificslicesare}

necessaryinordertomakeadistinctionbetweencomplete andpartialtears.VanDycketal.22_{suggestedthatcertainaxial}

andperpendicularviewswouldbemoreaccurateinmaking diagnosesbasedonmagneticresonance.Alongwithclinical examinationand measurement of the differential anterior translation, magnetic resonance imaging is important for definingandguidingthebesttreatment(Fig.1).

Arthroscopicevaluation

Arthroscopicevaluationhasbeenproposedbysomeauthors fordiagnosing partialtears.9,12,13,16,17 _{However,in the light}

ofthecurrentknowledge,thereisnoindicationfor system-atic arthroscopic evaluations for diagnosing such injuries. Arthroscopymakesitpossibletodiagnosethetypeofpartial tearand,togetherwiththeclinicalandimagingexaminations, itdeterminesthebesttypeofreconstructionincasesinwhich surgicaltreatmentisindicated(Fig.2).

Multifactorialtheory

Partial tears are common and account for 10% to 27% of ACLinjuries.9 _{Preservationofthe AMand PLbands isseen}

in 11% and 16% of the cases, respectively. The frequency of meniscal lesions is similar and the mean differential anterior translation is 4.49 and 4.97mm, respectively. The timethat elapsesbetweeninjury andsurgicaltreatment is shorter(fivemonths).3_{DeFrancoandBach}6 _proposeda

bet-ter approach in which multiple factors would be defined, suchthat asymmetricalLachmantests, negativepivotshift tests, differential anterior translation from 3 to 4.9mm and complementary positive evaluations using magnetic resonance imaging and arthroscopy would be taken into consideration.6,21,23

Treatment

The treatment needs to beindividualized and appropriate foreach patient’s needs. Identifyingpatients withlow and highriskofprogressionoftheclinicaldeficiencyoftheACL isfundamentalforprovidingtherapeuticguidance.Low-risk patients are the ones with low physical demands, with-out associated injuries or complaints ofinstability, whose clinical testsarenegative.Thesepatients’ signsand symp-toms generally tend not to progress and can be treated conservatively.9,21,23 _{High-risk patients are the ones with}

provenclinicalinstabilityand lifestylesthatpresent ahigh riskofnewtorsion.Inthesecases,thebestoptionwouldbe toperformselectionsurgicalreconstructionoftheACL.21,23

Thetreatmentstrategyalwaysneedstotakeinto consider-ationthesymptoms,clinicalexamination,percentageoffibers remaining,associatedinjuries,lengthoftimesincetheinjury anddailyphysicalworkdemands.

Conservativetreatment

The conservative treatments used include immobilization whilethepatientremainssymptomaticand then,afterthe acutephase,stimulationofcompletemovementand progres-siveweight-bearing.9,21,23_{Theprinciplesofrehabilitationfor}

patients with partialtears are the same as those usedfor patientswithcomplete tears.Thisrehabilitationconsistsof exercisesformuscle stretchingand strengthening and car-diovascular, proprioceptiveand adaptivetraining.24–26 _Pujol

et al.27 _{demonstrated that partial ACL tears may have the}

capacitytoheal,contrarytowhathadbeenthought.

Conservativetreatmentproducesgoodresultswhen cor-rectly indicated, with minimal reduction of activity level and without impairing stability.21,23,24 _{Other authors have}

to complete tears and that conservative treatment would implyworseclinicalandfunctionalresults.26,27 _Pujoletal.27

describedaseriesinwhich25%ofthepatientswithpartial ACLtearsevolvedwithfunctionalinstabilityoverthemedium tolongterm.Serialassessmentswouldbenecessaryinorder tomonitortherehabilitationandresiduallaxity,whichthus wouldenableevaluationofwhetherconservativetreatment shouldbemaintainedorwhetheritshouldbechangedtoa surgicalapproach.17,21,26–28

Surgicaltreatment

Indication

TreatmentwithselectiveACLreconstructionincasesof par-tial tears may bejustified bydifferent factors.The first of theseisclinical:manypartialtearsprogresstocompletetears withincreasingdifferentialanteriortranslationandthe con-sequentpossibilityofmeniscalandchondrallesions.9,16,17,28

Thesecondisbiological:thecentralfibersoftheACLprovide adequatevascularandnervoussuppliestothenewligaments. Mechanoreceptors present in the remaining ligament are responsibleforpreservingandrestoringthestabilityandjoint balance.3,4,7,27_{HistologicalevaluationsonACLremnantshave}

demonstratedthattheyhavethecapacitytoacceleratecell proliferation,revascularizationand,consequently,integration ofthegraftincasesofselectivereconstruction.27–31_Thethird

isepidemiological:theriskofdegenerativelesionssubsequent topartialtearshasnotyetbeenestablished,althoughKannus andJarvinen25 _{reportedthat15%oftheirpatientswith}

par-tialtearspresenteddegenerativelesionsaftereightyearsof follow-up.

Treatment

Selectivereconstruction has somepoints in common with anatomicalACLreconstruction: graftoptions, rehabilitation programandtimetakentoreturntophysicalpractices.The mostimportantdifferenceliesinthebiologicalconcept.Other differencesrelatetotunnelpositioningandmilling,alongwith thegraftdiameterandpassage.Theoptionsforsurgical treat-mentofpartialACLtearsincludethermalmeasures,classical reconstructionand selectivereconstruction.Thermal meas-ures andclassical reconstruction are notaddressedinthis review.

Thearthroscopicevaluation isstarted throughthe clas-sicalportals:anteromedialandanterolateral.Someauthors haveproposedthatanaccessoryanteromedialportalshould becreated:thiswouldfacilitateviewingthegraftandthe foot-prints.Sonnery-Cottetetal.29_{proposedthattheanterolateral}

portalshouldbeconstructedslightlyproximallyinorderto havebetterviewingandlessneedfordebridementofHoffa’s fat.Afteraninventoryofallcompartmentshasbeenmade, the associatedlesions are treatedand then the remaining fibersoftheACLareassessed.Thisevaluationisvisual(with confirmationofthepresenceofcontinuousfibersconnecting footprints)andmechanical,andisdonebothinasemi-flexed positionandina“figureof4”position.Tensionisassessedby meansofpalpationandviaclinicaltestsunderarthroscopic viewing.32,33

Graftselection

Thechoiceofgraftshouldfollowthesurgeon’sroutine. Sev-eral authors havereportedmaking increasinguseofflexor tendons, whichmay betriple or quadrupleand eitherfree or maintainedin theirtibialinsertions.3,4,9,13 _Thepresence

ofboneblocksmaymakepassagethroughthetunnelsthus created moredifficult.From theintercondylarspacethatis associated with preservation of greatest numbers of rem-nant fibers,agraft diameterof8mmhasbeen foundtobe mostappropriate.5,9,12,13_{Theconceptthatthegreaterthegraft}

diameteristhebetterthiswouldbeconflictswiththe anatom-icalconcept ofpreservation ofthe remnantsand with the biologyofhealingbetweentheseremnantsandthegraft.32,33

Technical

details

ReconstructionoftheAMband

Thearthroscopic procedure begins withmoderate debride-mentoftheremnantsoftheAMbandwithpreservationof thePLband.SieboldandFu34_{recommendedthatatibialguide}

atanangleof60◦_{shouldbeused,withanentrypointaround}

1.5cmmediallytotheanteriortuberosityofthetibia.The posi-tionofthefemoraltunnelshouldfollowthepresenceofthe remnantsinthe femurintheanatomicalposition. To con-structthistunnel,inside-outoroutside-inguidescanbeused. Millingshouldbedonemanuallyorbymeansoflow-velocity drilling,soastoavoidfurtherinjuringtheremainsoftheACL.

ReconstructionofthePLband

Thepositionofthetibialtunnelismoremedialandbegins around3.5cmmediallytotheanteriortuberosityofthetibia. Theintra-articularportionislocatedintheposteriorpartof the tibial insertionand 5mmmedially tothe lateral inter-condylareminence.Useofthefemoralremainsisthemost reliable wayoffinding thesiteforthefemoraltunnel.Itis constructedbymeansoftheanteromedialportalorusingan outside-intechnique.Fortunnelsconstructedbymeansofthe medialportal,attentionneedstobegiventotheriskof iatro-genic lesions inthemedialfemoralcondyleatthe timeof milling.

Graftfixation

Thefixationwilldependonthetechniqueused.Ifthe inside-out technique isused, interferencescrews orEndobutton®

are recommendedforthe femoralportion andinterference screws forthe tibialportion.If the outside-in techniqueis used,interferencescrewscanbeusedinbothtunnels.There isroomfordebateregardingwhetherthefixationshouldbe done withoutpre-tensioning,orwhetherit shouldbedone afterpre-tensioning,whichtheoreticallywouldensurebetter adaptationofthegraft.28,29,34_{Forselectivereconstructionof}

thePLband,fixationisdonewithflexionofbetween0◦ _and

10◦_{,whileforreconstructionoftheAMband,thefixationangle}

of20◦_.9,21,23,34_{Afterfixation,theentirerangeofmotionshould}

betested,withspecialattentiontoextension.If thisisnot achieved,itmaybeasourceofpainand/orlossofmovement.

Clinical

evaluation

Mottwasthefirstauthortoreportsatisfactoryclinicalresults from selective reconstructionafter acute ACL tearing.9,21,23

Adachietal.3,35_andOchietal.4,36_{publisheddataonpatient}

series inwhich they comparedselective and classical ACL reconstruction.Smallerdifferentialanteriortranslationwas foundintheselectivegroup.Thisobservationwasperhaps due tothe better vascularizationand reinnervation atthe timeofselectivereconstruction. In2009,Ochi etal.36

pub-lisheddataon anewseriesof45 patientswho underwent selectivereconstructionwithafollow-upoftwoyears.They showedusingmagneticresonanceimagingthatthe differen-tialanteriortranslationwaslessthan0.5mm,proprioception wasbetterandhealingwaseffectiveaftertheoperation.These findingscorroboratedthoseofastudyconductedin2002that demonstratedthattherewasanassociationbetweenthe pres-enceofmechanoreceptorsintheremainingfibersandbetter proprioception.4,36

Budaetal.5 _{evaluated47patientswhounderwent}

selec-tivereconstruction. Good or excellent clinical results were seenin95.7%ofthecases.Goodclinicalresultswere corre-latedwithintegrationofthegraftwiththeremainingfibers andwithpresenceofasignalonmagneticresonanceimaging. Attentionwasdrawntothefactthatinselective reconstruc-tionprocedures,thegraftneedstobebetween7and8mm, whichwouldavoidanexcessoffibersbetweentheremainder oftheACLandthegraft.5,32_{Sonnery-Cottetetal.}37_evaluated

36patientswho underwent reconstructionoftheAMband andobservedthatthedifferentialanteriortranslationwasless than0.8mm.Infollowinguppatientswhohadbeentreated withselectivereconstructionofpartialtears,Chouteauetal.38

demonstrated that the stability and proprioception of the treatedkneeweresimilartothoseofthenormalknee.

Few published papers have compared classical ACL reconstructionsandselectivereconstructionprocedures,with functionalandnon-functionalremnantligaments.Agreater numberofstudies wouldbeuseful inordertoevaluatethe environmentcreatedbytheremnantsandtheireffectongraft healing.Theresultsfromselectivereconstructionare encour-aging,althoughthere isstillalackofevidence thatwould proveitsrealbenefit.39

Final

remarks

PartialACL tears are being diagnosed more and more fre-quently.Theyaccountfor10–27%ofallsuchinjuries.There isno singledefinitionfor themin the literature.Theycan bediagnosedthroughacombinationofclinicalexamination andimagingexamination,withconfirmationthrough arthro-scopic examination.The pivotshift test under anesthesia, thehard-stopLachmantest,magneticresonancefindings,the levelandtypeofsportsactivity,thearthroscopicappearance oftheremnantligamentandthemechanicalpropertiesare

elementsusedbyorthopedistsfordecidingbetween conserva-tivetreatment,surgicaltreatmentwithreinforcementofthe native ACL(selectivereconstruction)andclassical (anatom-ical) ACL reconstruction. When there is an indication for surgery,preservationoftheremainingfibersisfundamental, inordertopreservethemechanical,vascularand propriocep-tivecapacityoftheknee.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgments

To the Knee Group of the Orthopedics and Traumatology Service,HospitalMadreTeresa,BeloHorizonte,Brazil,andto theSantyOrthopedicsCenter,Lyon,France.

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