Rev. bras. ortop. vol.48 número5

rev bras ortop.2013;48(5):465–468

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

Case

Report

Anchor

proximal

migration

in

the

medial

patellofemoral

ligament

reconstruction

in

skeletally

immature

patients

夽

,

夽夽

Fabiano

Kupczik

_,

_Marlus

_Eduardo

_Gunia

_Schiavon

_,

_Bruno

_Sbrissia

_,

_Lucas

_de

_Almeida

Vieira

,

Thiago

de

Moura

Bonilha

a_{MScinSurgeryfromPontifíciaUniversidadeCatólicadoParaná(PUC-PR);HeadoftheKneeSurgeryGroup,HospitalUniversitário}

Cajuru,PUC-PR,Curitiba,PR,Brazil

b_{OrthopedistandTraumatologist;MemberoftheKneeSurgeryGroup,HospitalUniversitárioCajuru,PUC-PR,Curitiba,PR,Brazil} c_{OrthopedistandTraumatologist;FellowofKneeSurgery,HospitalUniversitárioCajuru,PUC-PR,Curitiba,PR,Brazil}

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Articlehistory:

Received1December2012 Accepted15January2013

Keywords:

Child

Ligaments,Articular Patellardislocation/etiology Patellardislocation/surgery

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Themedialpatellofemoralligament(MPFL)injuryhasbeenconsideredinstrumentalin lat-eralpatellarinstabilityafterpatellardislocation.Consequently,thefocusonthestudyof thisligamentreconstructionhasincreasedinrecentyears.TheMPFLfemoralanatomical originpointhasgreatimportanceatthemomentofreconstructionsurgery,becauseagraft fixationinanonanatomicalpositionmayresultinmedialoverload,medialsubluxation ofthepatellaorexcessivetensioningofthegraftwithsubsequentfailure.Inthepediatric population,thelocationofthispointishighlightedbythepresenceoffemoralphysis.The literatureisstillcontroversialregardingthebestplacementofthegraft.Wedescribetwo casesofskeletallyimmaturepatientsinwhomLPFMreconstructionwasperformed.The femoralfixationwasthroughanchorsthatwereplacedabovethephysis.Withthegrowth anddevelopmentofthepatients,thefemoraloriginpointofthegraftmovedproximally, resultinginfailureinthesetwocases.

©2013SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

Migrac¸ão

proximal

de

âncora

na

reconstruc¸ão

do

ligamento

patelofemoral

medial

em

pacientes

esqueleticamente

imaturos

Palavras-chave:

Crianc¸a

Ligamentosarticulares Luxac¸ãopatelar/etiologia Luxac¸ãopatelar/cirurgia

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e

s

u

m

o

Oligamentopatelo-femoralmedial(LPFM)éaestruturamaislesadacomaluxac¸ãoaguda dapatelaetemsidoconsideradaalesãoessencialnainstabilidadelateral-patelar. Conse-quentemente,oenfoquenoestudodareconstruc¸ãodesseligamentotemaumentadonos últimosanos.OpontoanatômicodaorigemfemoraldoLPFMrecebegrandeimportânciano momentodareconstruc¸ão,poisafixac¸ãodoenxertoemumaposic¸ãonãoanatômicapode

夽

Pleasecitethisarticleas:KupczikF,GuniaSchiavonME,SbrissiaB,deAlmeidaVieiraL,deMouraBonilhaT.Migrac¸ãoproximalde âncoranareconstruc¸ãodoligamentopatelofemoralmedialempacientesesqueleticamenteimaturos.RevBrasOrtop.2013;48:465–468.

夽夽

TrabalhorealizadonoHospitalUniversitárioCajuru,PontifíciaUniversidadeCatólicadoParaná,Curitiba,PR,Brasil. ∗ _{Correspondingauthorat:AvenidaPresidenteAffonsoCamargo,955/301,CEP80050-370,Curitiba,PR,Brazil.}

E-mail:lucasvieiracb@gmail.com(L.deAlmeidaVieira).

466

acarretarsobrecargamedial,luxac¸ãomedialdapatelaoutensionamentoexcessivodo enx-erto,comsuaposteriorfalha.Napopulac¸ãopediátrica,alocalizac¸ãodessaorigemfemoral ganhadestaque pelapresenc¸ada fisedofêmur distal.Aliteraturaaindaécontroversa comrelac¸ãoaomelhorposicionamentodoenxerto.Descrevemosdoiscasosemquefoi feitaareconstruc¸ãodoLPFMempacientesesqueleticamenteimaturos.Afixac¸ãofemoral sedeupor meiodeâncorasqueforamposicionadasacimada fise.Comocrescimento eodesenvolvimentodospacientes,opontodeorigemfemoraldoneoligamentomigrou proximalmenteeacarretouafalhadoenxertonessesdoiscasos.

©2013SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

Reconstructionofthemedialpatellofemoralligament(MPFL) isthe preferredprocedure forpatients withchroniclateral patellarinstabilitywhohavenormalalignmentoftheextensor apparatusanddeficiencyoftheproximalmedialrestrictors.1 Avarietyoftechniqueshavebeendescribed,withdifferent typesofgraftsandfixationmethods.However, nonanatom-icalreconstructionleadstoalterationofthekinematicsand loaddistributioninthepatellofemoraljoint.2

Inskeletallyimmaturepatients,locatingthecorrectpoint forthefemoralorigingainsevengreaterimportancebecause ofthepresenceofthegrowthplatelineinthedistalportion ofthe femur. Controversy still exists in this regard in the literature.3

TheaimofthisreportwastodescribetwocasesofMPFL reconstructioninwhichfemoralfixationwasperformedby meansofanchorsthatwereproximaltothedistalgrowthplate ofthefemur.

Case

1

Thepatientwasaschoolgirlwhowas12yearsoldatthattime. Shehad undergonebilateralMPFLreconstructionusingthe medialthirdofthepatellartendonandmetalanchorsinthe femur.

Afterapproximatelythreeyearsofevolution,shesuffered asprainedrightkneewithinjurytotheanteriorcruciate lig-ament(ACL)andtothereconstructedMPFL.Shewastreated surgicallywithreconstructionoftheACLandrevisionofthe MPFL,andsheevolvedwell.

Twoyearslater,atareassessmentconsultation,shewas seentobefreefromsymptomsintherightkneebutreported some pain in the left knee, which was alleviated through medication.Inthephysicalexamination,shepresented lat-eralsubluxationoftheleftpatella.Inthecontrolradiographs (Figs.1and2),itcouldbeseenthattheanchorshadmigrated throughthemedialcorticalboneofthe leftfemurbecause oftheirpositioningabovethegrowthplateandthepatient’s growth.

Case

2

Thepatientwasaschoolgirlwhounderwentleft-sideMPFL reconstructionattheageof12years,beforethemenarche.For thispatienttoo,thetechniqueconsistedofusingthemedial

thirdofthepatellartendon,withfemoralfixationdoneusing abioabsorbableanchor.Thepatienthadalreadybeentreated forpatellarinstabilityconservativelyandusingsurgical tech-niquesotherthatMPFLreconstruction,butwithoutsuccess.

Thepatientevolvedwellandmaintainedpatellarstability foraroundtwoyears.Uponreassessmentafterthisperiod, shepresentedslightpatellarsubluxationatthestartof flex-ion.Oneyearlater,thepatientagainpresentedinstabilityand lateral subluxationofthe patella.In imagingexaminations (Fig.3),proximalmigrationoftheanchorcouldbeseen.This hadledtograftfailure.Revisionsurgerywasindicated.

Discussion

To treatpatellarinstability, morethan onehundred proce-dures have so far been described. This demonstrates the

rev bras ortop.2 0 1 3;48(5):465–468

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Fig.2–Lateralradiographofthekneeshowingthe

proximalmigrationofmetalanchorsfromreconstructionof themedialpatellofemoralligament(MPFL)withpositioning abovethegrowthplateinaskeletallyimmaturepatient.

complexityofachievingstabilityforthisjoint,whichdepends onavarietyoffactors.4_{Recently,the focusonMPFL} recon-structionhasincreased.Severalstudieshavedemonstrated thattheMPFListheanatomicalstructurethatismostoften injured following patellar dislocation and that this is the essentialinjuryforthispathologicalcondition.5

Inamanneranalogoustoanatomicalreconstructionofthe ACL,the idealistocorrectlylocate theorigin ofthe MPFL. Noreconstructionwillbeanatomicallyperfect,butattention needstobepaidtomakingthisascloseaspossible.1

Intheliterature,themethodforlocatingthefemoralorigin oftheMPFLthatismostusedistheonedescribedbySchöttle etal.,6_{asmodifiedbyServienetal.}5_{Onalateral-view} radio-graphoftheknee,astraightlinealongtheposteriorcortical boneofthediaphysisistracedout.Anotherstraight lineis tracedoutperpendicularlytothefirstline,intheregionofthe posteriororiginofthefemoralcondyle.Thispointislocated onemillimeteranteriorlytothestraightlineoftheposterior corticalboneand2.5mmdistallytothestraight lineofthe posteriorportionofthecondyle.6

Schöttle’s descriptionwas made throughstudying adult cadavers.Sheaetal.7 _{adaptedtheradiographicparameters} forthepediatricpopulationandfoundfromevaluatinglateral radiographsthattheoriginoftheMPFLwasproximaltothe growthplatesby2.7±1.1mmingirlsand4.6±2.4mminboys. Nelitzetal.3 _{conductedan evaluationsimilartothat of} Sheaetal.7_{However,inadditiontothelateralviewoftheknee,}

Fig.3–Magneticresonanceimagingoftheleftknee demonstratingtheproximalmigrationofthebioabsorbable anchortothemedialcorticalboneofthefemur.Theanchor hadbeenpositionedproximallytothegrowthplatein reconstructingthemedialpatellofemoralligament(MPFL).

theyalsogaveemphasistothefrontalprojection.Accordingto theseauthors,thedistalepiphysisofthefemurhasaconcave shape, whichisfollowed bythe growth plate.Thus, in lat-eralprojection,onlythecentralportionofthegrowthplateis viewed.Hence,thepointproposedbySchöttlewouldbeclose tothegrowthplateline.However,infrontalview,themedial borderofthegrowthplateismoreproximalthanitscentral part,andsothepointoforiginoftheMPFLwouldbedistalto thegrowthplatebecauseofthisconcavity.3_{Inallthepatients} evaluated,thefemoraloriginwasdistaltothegrowthplateby ameanof6.4mm.StudiesoncadaversbyLaPradeetal.8_and Baldwin9_{alsoconfirmedthedistalpositioningoftheoriginof} theMPFL.

Inadultpatients,fixationoftheMPFLgraftinamore proxi-malpositionleadstoincreasedmedialpatellofemoralloading, medial subluxation and excessive tensioning of the graft, whichmayfailandcauserecurrenceoflateralinstability.1,10 Constructionofanaccessofadequatesize,identificationof the bone structuresthat serve as parameters (medial epi-condyleandadductingtubercle)anduseoffluoroscopyarethe mainrecommendationsforlocatingthefemoralpointduring theoperation.1,5

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Withtheexperienceofthesetwocases,andfrom review-ingthecurrentliterature,weconcludethattheideallocation forgraftfixationinreconstructingtheMPFLisdistallytothe growthplateofthedistalfemur.

Conflicts

of

interest

Theauthorsdeclarethattherewerenoconflictsofinterest.

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3. NelitzM,DornacherD,DreyhauptJ,ReichelH,LippacherS. Therelationofthedistalfemoralphysisandthemedial patellofemoralligament.KneeSurgSportsTraumatol Arthrosc.2011;19:2067–71.

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5.ServienE,FritschB,LustigS,DemeyG,DebargeR,LapraC, etal.Invivopositioninganalysisofmedialpatellofemoral ligamentreconstruction.AmJSportsMed.2011;39: 134–9.

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ligament.Arthroscopy.2010;26:1083–7.

8.LaPradeRF,EngebretsenAH,LyTV,JohansenS,WentorfFA, EngebretsenL.Theanatomyofthemedialpartoftheknee.J BoneJointSurgAm.2007;89:2000–10.

9.BaldwinJL.Theanatomyofthemedialpatellofemoral ligament.AmJSportsMed.2009;37:

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