Rev. bras. ortop. vol.49 número6

rev bras ortop.2014;49(6):671–674

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

Case

Report

Pre-tibial

synovial

cyst

after

reconstruction

of

the

anterior

cruciate

ligament:

case

report

夽,夽夽

Luís

Eduardo

Pedigoni

Bulisani

,

Erickson

Bulisani

a_{BrazilianSocietyofKneeSurgery(SBCJ),SãoPaulo,SP,Brazil}

b_{UnimedJundiaí,Jundiaí,SP,Brazil}

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r

t

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c

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e

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Articlehistory: Received24July2013 Accepted6August2013 Availableonline18October2014

Keywords:

Anteriorcruciateligament Postoperativecomplications Synovialcyst

Bonescrew

a

b

s

t

r

a

c

t

Arthroscopicreconstructionoftheanteriorcruciateligamenthasbeenmodernizedthrough newsurgicaltechniquesandnewmaterials.Whentibialfixationisperformedusingan absorbablescrew,complicationsmayoccur,suchasformationofapre-tibialcyst.Thecase describedhereisaboutapatientwhopresentedananteromedialsynovialcystinhisright knee,threeyearsafterhavingundergoneACLreconstruction.Thepatientdidnotpresent anypainnoranycomplaintsotherthanamassthatprogressivelyincreasedinsize, wors-enedafterphysicalactivities.Imagingexaminationswererequested:simpleradiographyof thekneeandmagneticresonance.Anteromedialimagingofthekneeshowedamasswith well-delimitedbordersandinternalfluidcontent,suggestiveofasynovialcyst,with com-municationwiththejointcavitythroughthetibialtunnel,withoutpresentingenlargement orabsorptionofthebonetunnel.Thecystwassurgicallyresectedandthetibialtunnel occlu-sionwasperformedusingaboneplug.Thediagnosisofasynovialcystwassubsequently confirmedthroughtheresultsfromtheanatomopathologicalexamination.Thepatient pre-sentedgoodclinicalevolution,withdisappearanceofthesymptomsandareturntophysical activities.

©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.Allrightsreserved.

Cisto

sinovial

pré-tibial

após

reconstruc¸ão

do

LCA

–

Relato

de

caso

Palavras-chave:

Ligamentocruzadoanterior Complicac¸õespós-operatórias Cistosinovial

Parafusoósseo

r

e

s

u

m

o

Areconstruc¸ãodoligamentocruzadoanterior(LCA)porviaartroscópicavemsendo mod-ernizadapornovastécnicascirúrgicasenovosmateriais.Quandofeitaafixac¸ãotibialcom parafusoabsorvívelpodemocorrercomplicac¸ões,comoaformac¸ãodeumcistopré-tibial. Ocasoemquestãoédeumpacientequeapresentouumcistosinovialanteromedialem joelhodireitotrêsanosapóstersidosubmetidoareconstruc¸ãodoLCA.Opacientenão apresentavadorououtrasqueixas,apenasmassadeaumentoprogressivo,compioriaapós

夽

Pleasecitethisarticleas:BulisaniLEP,BulisaniE.Cistosinovialpré-tibialapósreconstruc¸ãodoLCA–Relatodecaso.RevBrasOrtop. 2014;49:671–674.

夽夽

WorkdevelopedattheUnimedHospital,Jundiaí,SãoPaulo,Brazil. ∗ _{Correspondingauthor.}

E-mail:eduardobulisani@hotmail.com(L.E.P.Bulisani). http://dx.doi.org/10.1016/j.rboe.2014.10.002

672

atividadesfísicas.Foramsolicitadosexames deimagem:radiografiassimplesdojoelho quenãoapresentavamalterac¸ões;eressonânciamagnéticacomimagemanteromedialem joelhosugestivadecistosinovial.Apresentavabordasbemdelimitadaseconteúdolíquido interno,comcomunicac¸ãocomacavidadearticularatravésdotúneltibial,semapresentar alargamentoouabsorc¸ãodotúnelósseo.Foramfeitasressecc¸ãocirúrgicadocistoeoclusão dotúneltibialcomtampãoósseo,composteriorconfirmac¸ãododiagnósticodecistosinovial apósresultadodoexameanatomopatológico.Opacienteapresentouboaevoluc¸ãoclínica, comdesaparecimentodossintomaseretornoàsatividadesfísicas.

©2014SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Todososdireitosreservados.

Introduction

Over recent decades, reconstruction of the anterior cruci-ateligament(ACL)bymeansofarthroscopictechniqueshas becomeastandardsurgicaltreatmentforkneesurgeons,since itresultsingreaterreliefofpostoperativepainand improve-mentofkneestabilityandrangeofmotion.Withevolutionof thesurgicaltechniquesandmaterialsused,graftfixationin itsfemoralandtibialtunnelshasbecomemoresecure,such thateasyslackeningofthereconstructedligamentisavoided. Amongthesematerialsareabsorbablescrews,whicharevery frequentlyused.However,withthisadvance,new complica-tionssuchastheemergenceofpre-tibialsynovialcystshave arisen.Theetiologyofthesecystsremainstobeclarified.1,2

Thepresentcasereporthad theaimofdemonstratinga possiblerelationshipbetweenuseofabsorbablescrews(used fortibialfixationoftheACLgraft)andsubsequentformation ofapre-tibialsynovialcyst.

Case

report

Thepatientwasa43-year-oldwhite manwithahistoryof ACLreconstructionintherightkneein2009.Hereturnedto theconsultationofficeinJanuary2013withacomplaintofa palpablemassinthiskneethatwasprogressivelyincreasing insize.

Thepatientreportedthatthisconditionhadstartedaround threeyearsafterthesurgery(i.e.sixmonthsbeforecomingfor theconsultation)and,sincethen,ithadpresentedprogressive increasesinsize,withworseningafterphysicaleffort.Hesaid thathehadnotsufferedandnewinjuriesorsprainsandhe didnotpresentanypainorothercomplaints.

Physical examination showed increased volume in the anteriorregionoftheknee, abovethesurgicalscarrelating toharvestingofgraftsfromthesemitendinosusandgracilis tendons.Therewasaroundedmassofapproximatediameter 3cm, whichwascompressibleandhadrubberyconsistency (Figs.1and2).Therewerenosignsorsymptomsofjoint insta-bilityoralterationstotherangeofmotion.

Kneeradiographswererequested,andthesedemonstrated thatthetibialandfemoraltunnelsdidnotdifferindiameter fromwhatwasconstructedatthetimeofthesurgery.There wasanEndobuttoninthelateral femoralcorticalboneand therewere no other alterations orbone images. For better

Fig.1–Appearanceatphysicalexamination,with increasedvolumeintheanteriorregionoftheknee.

elucidationofthediagnosis,magneticresonanceimagingof therightkneewasrequested.Thisshowedananteromedial cystinthekneewithwelldelimitedborders,whichcontained fluidandwassuggestiveofasynovialcyst(Fig.3).Theimage depictingfluidcontinuedthroughthebonetunneltothejoint cavity, which demonstrated communication between the synovialcystandthejoint.Thetibialtunneldidnotpresent any wideningor boneabsorptionand theabsorbablescrew couldnotbeseen.Theanteriorcruciateneoligamentdidnot presentanyalterations.

rev bras ortop.2014;49(6):671–674

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Fig.2–Locationabovethesurgicalscar.

synovialcyst.Thephysicalexaminationperformedwiththe patientunderanesthesiadidnotshowanysignsofanterior instability.

Sixmonthsafterthisoperation,thepatientdidnotpresent anyabnormalitiesoninspectionoftheknee,oranychanges toits rangeofmotion,andhehad returnedtohisphysical activities.

Theabsorbablescrewthathadbeenusedforgraftfixation in2009wasmade ofhydroxyapatitewithpoly-l-lacticacid

(PLLA).Theanatomopathologicalresultwasasynovialcyst

andnopresenceofanyinflammatoryreactionorremnantsof thematerialoftheabsorbablescrewwereobserved.

Discussion

EvenwithevolutionofarthroscopicACLreconstruction, sev-eral complicationsmayoccur, goingfrom thetime ofgraft harvesting tolate-stagepostoperativeissues.Tibialfixation usingabioabsorbablefixationscrewmayevolvewithcertain complications,andoneofthesecomprisesformationofa pre-tibialcyst.1–3

When the cyst forms, there is a communication canal betweenitand thejoint,calledapedicle. Itisthroughthis pediclethatextravasationofthesynovialfluidintothecyst takesplace.Asthecystgrowsinsize,itcausescompression ofthesurroundingtissues.Thecystitselfdoesnothurt:the painresultsfromthiscompressionorirritationofthetissues aroundit.4_{Inthecaseofthepresentpatient,theonly} com-plaintwasesthetic,becauseoftheprogressivelyincreasing mass.

Thefewpreviousreportsonformationofpre-tibialcysts afterACLreconstructionhavedescribedseveraltypesofgrafts and fixation techniques, which makes it difficultto estab-lishtheetiology.Cystformationoccursonaverage3–4years afterthesurgicaltreatment.5_{Someoftheetiological} explana-tionsproposedhaveimplicatedleakageofthesynovialfluid throughthetibialtunnel,6,7_{whichcouldbecausedbyatunnel} withadifferenceindiameterinrelationtothegraft,5_eccentric positioningofthetendoninthebonetunnel,7_intraosseous necrosisofthetendon,6,8_{breakageoftheabsorbablescrew}3 andinstabilitythroughmicromovementsofthetendon,which wouldleadtoincreasedtunneldiameter.3,5,6

Severalbioabsorbablescrewmaterialsareavailable:PLLA, poly-d-lactic acid (PDLA), poly-dl-lactic acid (PDLLA) and

polyglycolicacid(PGA).Thesematerialsgothroughfivestages ofdegradation:hydration,depolymerization,lossofintegrity ofthemass,absorptionandelimination.9_Duringthe degra-dation,oncethescrewhasbeenhydrolyzed,itfragmentsand mayreleaseacidhydrolysisproductsthatareharmfultothe surroundingtissue.Therefore,thecompositionofthescrew materialwillprobablyhaveaneffectonitsdegradationand absorptionrates,whichmayberelatedtodevelopmentofa cystcausedbyaninflammatoryreactiontoaforeignbody.3,7

Another cause of cyst formation is probably related to incompleteincorporationofthetendongraftmaterialinside

Slice Sagittal

674

Axial slice Coronal slice

Fig.4–Magneticresonanceimaging(coronalandaxialslices)showingcontinuityofthefluidcontentthroughthebone tunneltothejointcavity,thusdemonstratingcommunicationbetweenthesynovialcystandthejoint.

thebonetunnel.Thislackoffullintegrationofthegraft in thebonetunnelleadstoformationofapedicleand subse-quentlytoasynovialcyst.Thishasbeencorrelatedwithuse ofgrafts fromflexortendons(semitendinosusand gracilis), whichdonothaveaboneblockthatconsolidatesandoccludes thetunnelandmaycausecystformation.5

However,thepediclefromthecyst needstobe differen-tiatedfromaccumulationsinthebonetunnels,whicharea commonfindinginmagneticresonanceimagingduringthe first year afterACL reconstruction using grafts from flexor tendons.Theseaccumulationsgenerallydisappearovertime: theydonotevolvetocystformationorleadtotunnel expan-sion and they are not associated with clinical instability. Sandersetal.2_{reportedsuchaccumulationsinsevenoftheir} eightpatientsoverapostoperativeperiodof18months, with-outcystformationinanyofthem.Furthermore,manyscrews are cannulated and therefore communication between the jointandthepre-tibialareaprobablyexistsforsomemonthsto yearsaftertheoperation,butinmostcasesnocystdevelops.2,3 Forthisreason,ithasbeenreportedthatthetypeof mate-rialofthebioabsorbable screwmay havesomeroleincyst formation.1

GiventhenumberofACLreconstructionsperformedusing bioabsorbable screws and the rarity ofsymptomatic cysts, theremaybesomerelationshipwiththepatientswhodevelop suchcysts.Althoughtheuseofabsorbablematerialsseemsto bewelltolerated,withoutanyinflammatoryresponseeither experimentallyorclinically,thesepatientsmayhavegreater sensitivitytosuch materialsor toparticles ofagiven size duringabsorptionofthesematerials.Thefactorsthat predis-posetowarddevelopmentofasterileinflammatoryreaction remainobscure.Futureresearchshouldcontinuetodelineate theeffectsofbiomaterialsintermsofscrewdegradationand cystformationrates.Pre-tibialcystsshouldbeconsideredto beapossiblecomplicationofACLreconstructionwhen tib-ialfixationisaccomplishedusingbioabsorbablescrewsand flexortendons.Accordingtotheliterature,patientsfollowed upaftercystremovalhavepresentedgoodevolutionwith dis-appearanceofsymptoms.1

In the case of our patient, magnetic resonance imag-ing showed a communication between the joint and the area of the cyst, which may explain its formation (Fig. 4). However,the etiology ofthecyst remains uncertainand it mayhaveoccurredthroughincompletehealingofthegraft fromthe flexortendonsorthrough aforeign bodyreaction

withthescrewmaterial.Therewasnotunnelenlargement, bone absorption or sign ofinstability that could provide a correlationbetweenmicromovementsandpresenceof com-municationfromthecysttothejoint.Afterresectionofthe cyst,thepatientevolvedoverasix-monthperiodwithoutany clinicalcomplainsandwithdisappearanceofthesymptoms andreturntophysicalactivities.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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2.SandersTG,TallMA,MulloyJP,LeisHT.Fluidcollectionsinthe osseoustunnelduringthefirstyearafteranteriorcruciate ligamentrepairusinganautologoushamstringgraft:natural historyandclinicalcorrelation.JComputAssistTomogr. 2002;26(4):617–21.

3.TsudaE,IshibashiY,TazawaK,SatoH,KusumiT,TohS. Pretibialcystformationafteranteriorcruciateligament reconstructionwithahamstringtendonautograft. Arthroscopy.2006;22(6):691.e1–6.

4.FeldmannDD,FanelliGC.Developmentofasynovialcyst followinganteriorcruciateligamentreconstruction. Arthroscopy.2001;17(2):200–2.

5.SimonianPT,WickiewiczTL,O’BrienSJ,DinesJS,SchatzJA, WarrenRF.Pretibialcystformationafteranteriorcruciate ligamentsurgerywithsofttissueautografts.Arthroscopy. 1998;14(2):215–20.

6.VictoroffBN,PaulosL,BeckC,GoodfellowDB.Subcutaneous pretibialcystformationassociatedwithanteriorcruciate ligamentallografts:areportoffourcasesandliteraturereview. Arthroscopy.1995;11(4):486–94.

7.WeilerA,HoffmannRF,StahelinAC,HellingHJ,SudkampNP. Biodegradableimplantsinsportsmedicine:thebiologicalbase. Arthroscopy.2000;16(3):305–21.

8.WilliamsRJ.Controversiesinkneesurgery.NewYork:Oxford UniversityPress,Inc.;2004.