Rev. bras. ortop. vol.52 número5

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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Original

Article

Conventional

plate

and

screws

in

medial

opening-wedge

high

tibial

osteotomy:

are

they

sufficiently

stable?

A

retrospective

study

夽

Rodrigo

Salim

_,

_Fabricio

_Fogagnolo,

_Mauricio

_Martins

_Perina,

_Ugo

_Messas

_Rubio,

Mauricio

Kfuri

Junior

UniversidadedeSãoPaulo,FaculdadedeMedicina,HospitaldasClínicas,RibeirãoPreto,SP,Brazil

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Articlehistory: Received27June2016 Accepted9September2016 Availableonline3January2017

Keywords:

Retrospectivestudy Osteotomy Knee Osteoarthritis

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Objective:Opening-wedgeosteotomyoftheproximaltibiaisawidelyperformedprocedure fortreatingmedialgonarthrosisinactivepatientsandinthepresenceofvarusmalalignment ofthelowerlimb.Thefixationmethodiscontroversial,andtheuseofconventionalimplants hasbeenabandonedinfavorofimplantswithmoremodernlockingscrews.Theaimofthe presentclinicalstudywastoassessthemaintenanceofthecorrectionachievedincases whereinfixationwasperformedusingconventionalimplants.

Methods:Thisretrospectivestudyincluded51patientswhounderwentopening-wedgehigh tibialosteotomywhereinfixationwasperformedusingconventionalimplants(4.5-mmDCP plateandnon-lockingscrews).Radiologicalfindingsregardingpatellarheight,tibialslope, andvaruscorrectionpostoperativelyandafterconsolidationwereanalyzedtoassessthe maintenanceofthecorrectionachievedbyosteotomy.

Results:Themeanlossofcorrectionangle,calculatedbythedifferencebetweenthe cor-rection anglein theimmediatepostoperative period andthatafter consolidation,was 0.92◦_±0.9◦_{.In addition, changes in patellar height determinedby the Blackburne–Peel}

method andinthesagittal slopeofthe tibialplateauwerenot significant orclinically relevant.

Conclusions: Theuseofconventionalplatesandscrewsisviableinthefixationof opening-wedgehightibialosteotomybecausetheyprovideenoughstabilitytomaintaintheachieved correctionuntilconsolidation,withoutsignificantchanges.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublishedbyElsevierEditora Ltda.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

夽

WorkperformedintheUniversidadedeSãoPaulo,FaculdadedeMedicina,HospitaldasClínicas,DepartamentodeBiomecânica, MedicinaeReabilitac¸ãodoAparelhoLocomotor,RibeirãoPreto,SP,Brazil.

∗ _{Correspondingauthor.}

E-mail:[email protected](R.Salim). http://dx.doi.org/10.1016/j.rboe.2016.09.007

O

sistema

convencional

de

placa

e

parafusos

na

osteotomia

tibial

alta

com

cunha

de

abertura

medial

é

suficientemente

estável?

Um

estudo

retrospectivo

Palavras-chave: Estudoretrospectivo Osteotomia Joelho Osteoartrite

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e

s

u

m

o

Objetivo:Aosteotomiacomcunhadeaberturadatíbiaproximaléumprocedimento ampla-menterealizadoparaotratamentodagonartrosemedialempacientesativosenapresenc¸a demaualinhamentoemvarodomembroinferior.Ométododefixac¸ãoécontroversoeo usodeimplantesconvencionaisfoisubstituídopelousodeimplantescomparafusosde bloqueiomaismodernos.Oobjetivodopresenteestudoclínicofoiavaliaramanutenc¸ãoda correc¸ãorealizadanoscasosemqueafixac¸ãofoirealizadacomimplantesconvencionais. Métodos: Esteestudoretrospectivoincluiu51pacientessubmetidosaosteotomiatibialalta comcunhadeaberturaemqueafixac¸ãofoirealizadautilizandoimplantesconvencionais (placadeDCPde4,5mmeparafusosnãobloqueados).Osachadosradiológicosreferentes àalturadapatela,àinclinac¸ãotibialeàcorrec¸ãodovaronopós-operatórioimediatoe apósconsolidac¸ãoforamanalisadosparaavaliaramanutenc¸ãoda correc¸ãoobtidapela osteotomia.

Resultados: Aperdamédiadeângulodecorrec¸ão,calculadapeladiferenc¸aentreoângulode correc¸ãonopós-operatórioimediatoeapósaconsolidac¸ão,foide0,92◦_±0,9◦_.Alémdisso,

alterac¸õesnaalturapatelar, avaliadaspelométodo deBlackburne-Peel,enainclinac¸ão sagitaldoplatôtibialnãoforamsignificativasouclinicamenterelevantes.

Conclusão: Ousodeplacaseparafusosconvencionaiséumaalternativaviávelnafixac¸ão daosteotomiatibialaltacomcunhadeabertura,poisproporcionamestabilidadesuficiente paramanteracorrec¸ãoobtidaatéaconsolidac¸ão,semalterac¸õessignificativas.

©2016SociedadeBrasileiradeOrtopediaeTraumatologia.PublicadoporElsevier EditoraLtda.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Proximaltibialosteotomyisawidelyperformedsurgical pro-cedureforthetreatmentofunicompartimentalkneearthrosis associatedwiththemalalignmentofthemechanicalaxisof thelimb(varus), particularlyinrelatively youngand active patients.Theprocedureallowsarthroplastytobedelayedfor morethan10yearsinapproximately80%ofpatients.1,2_Medial openingwedgehightibialosteotomyhasbecomeincreasingly popularinrecentyearsbecauseitisaneasytechniquethat allowsfineadjustmentstothedesiredcorrectionduringthe surgicalprocedure3_{anddoesnotrequireasurgicalapproach} to the fibula or superior tibiofibular articulation. However, this typeofprocedure resultsina smallbonecontact sur-faceatthe osteotomysitethatisoftenlimitedtotheapex ofosteotomy,whichincreasesthechanceoffixationfailure andlossofcorrection.4_{Forthisreason,severalauthorshave} stressedtheimportanceofpreservingtheintegrityofthe cor-tex oppositethe baseofthe osteotomywedgeas ameans ofpreventingsecondarydeformities,andthereare descrip-tionsofsurgicalstrategiesforthispurpose.5_{Biomechanical} andclinicalstudieshaveemphasizedtheimportanceofthe implantusedinthefixationofopeningwedgeosteotomies,in additiontothegeometryoftheosteotomy,andnovelimplants havebeendevelopedwiththeaimofincreasingstability.6,7 Someimplantshavewedgesorblocksofvaryingsizesthatare placedsoastosupportthecortexoftheopeningwedge,and othersuselockingscrewsthatcreateangularstabilityrelative

totheplates.8_{Indevelopingcountries,itissometimes} diffi-culttoobtainthemostmodernandexpensiveimplantsfor thefixationofosteotomies,andconventionalimplantsthat theoreticallywouldnotbethefirstchoiceareusedasan alter-native.Thisretrospectivestudyreportsaseriesofcasesofhigh tibialosteotomyperformedusingthemedialopeningwedge technique,whereinthefixationswereperformedusing con-ventionalDCP(Synthes,Paoli,USA)platesandinvestigatesthe efficacyoftheseimplantsinthemaintenanceoftheachieved correctionuntilunionoftheosteotomysite.

Methods

patientswas48.8years (range,18–62years). Allprocedures wereperformedbyoneofthehospital’sseniorsurgeonsor undertheirsupervision.ThestudywasapprovedbytheEthics Committee in Medical Research. Radiographic assessment wasperformedpreoperativelyandineveryfollow-upvisitat 4,8,16and52weekspostoperatively,bymeansofastanding anteroposterior(AP)weightbearingviewandaregularlateral view.Fulllengthpanoramicviewswereobtainedatthe ini-tialassessmentpreoperativelyandatthe52-weeks-mark.For anteroposteriorradiographs,thepatientsstoodwiththe patel-laecenteredoverthefemoralcondylesandfeetstraightahead toattainatrueanteroposteriorimageandtocontrolforeffects offoot rotationonmeasuresoflower extremityalignment. TheX-raybeamwascenteredontheknee atadistanceof 2.5metersandbeamexposurewasdeterminedbasedoneach patient’slegmass.Kneearthrosiswasclassifiedaccordingto themodifiedAhlbäckclassification.9

Surgicaltechnique

Thepatientsunderwent ligamentexaminationunder anes-thesia and were placed in the supine position on the radiolucenttable,withapneumatictourniquetonthethigh. Allpatientshadundergonediagnosticarthroscopytoassess thestateofthelateralcompartmentoftheknee and treat-mentofunstablechondralormeniscallesions.Anteromedial incisions (ofapproximately 8cm) were madelengthwise in thekneeskin,andtheproximallimitwaslocated1–2cm dis-tallyfromthejointline.Thecruralfasciaandpesanserinus tendonswereelevatedandretractedposteriorly.Themedial collateral ligament was completely released from its tibial insertioninallcases.AHohmann-typeretractor,whichwas posteriorly placedto thetibia, protectedthe neurovascular structures.Thedesignandcutoftheosteotomywasfollowed accordingtothetechniquedescribedbyStaubli.8_Underimage intensification,thefirstosteotomyinthecoronalplanewas

performedposteriorly totheanteriortibialtuberosityinan obliquemanner.Itstarted1cmproximallytothepatellar liga-mentinsertionandextendeddistallyandposteriorlyuntilthe secondaxialcomponentoftheosteotomywasmet.Ina pro-fileview,thetwolinesofosteotomyformedanobtuseangle. Guidewireswereobliquelyinsertedtoguidethemedial open-ingwedgeaxialtibialosteotomy,thecutofwhichstartedatthe medialcortexofthetibia4cmfromthejointlineandextended totheprojectionoftheheadofthefibulainthe anteroposte-riorview.Thiscutwasdesignedtoendatapointlocated2cm fromthejointlineand1cmfromthelateralcortexofthetibia, whichwaspreserved(incompleteosteotomy).Theosteotomy wasperformedwithanoscillatingsawandbroadosteotomes, andthewedgewasperformedtoachievethedesired correc-tion.Abladeretractorwasposteriorlyplacedinthemedial cortexofthetibiaforthispurpose.Theaxiswascorrected withtheaidofthecauterycord,extendedfromthecenterof thefemoralheadtothecenteroftheankletoreproducethe mechanicalaxisofthelimb.TheFujisawapointwasusedasa referenceforthecorrectionlimit,thuseliminatingtheneedof preoperativeplanningoftheamountofangularcorrection.8,10 Thefixationofthe osteotomywassubsequently performed usinga4.5-mmDCPplatewithfourorfiveholes.Spongious screws(6.5mm)andcorticalscrews(4.5mm)wereusedinthe metaphysisanddiaphysis,respectively.Thefixationwas sup-plementedinallcaseswitha6.5-mmspongiousandpartially threadedscrewthatcrossedtheosteotomy,insertedthrough thelateralcortexproximallytotheapexoftheosteotomyand extending tothe medialplateau, as described byPaccola.5

Fig. 1shows the radiographs of a patient who underwent surgery with the described technique. After fixation, bone grafting withautologousbone extracted from thepatient’s iliaccrestwasusuallyperformedincasesinwhichthe open-ing ofthe medialcortex in the osteotomy site was larger than1cm(arbitrarilydefinedininstitution’sroutine)oratthe discretionoftheseniorsurgeon.Intheremainingpatients, thegapwasfilledwithabsorbablegelatinsponge(Gelfoam®,

Fig.2–Radiographsinanteroposterior(AP)andprofile(P)viewsofanopeningwedgeosteotomydemonstratingthe methodsusedtomakemeasurements.

Pfizer),andthefragmentsofspongiousboneremovedfromthe osteotomyitselfwereplacedintheprojectionofthecortex, aroundthegelatinsponge.Intraoperativeradiographicimages wereobtainedinallcasesattheendofprocedure.

Physiotherapywasstartedonthefirstdayafterthe proce-dure,withexercisestoimprovetherangeofmovementsand isometricexercisestostrengthentheglutealandquadriceps musclesandforactivemobilizationoftheknee.Weight bear-ingwaspartiallylimitedforeightweeksandwasallowedto increaseaftertheverificationofconsolidationinradiographs obtainedat4,8,16,and52weekspostoperatively.No immo-bilizationororthosiswasrequired.

Radiologicalassessment

To assess the maintenance of the correction achieved by osteotomy,theanglesoftheproximalpartofthetibiawere measured according to the method described by Poignard etal.11_{Thevaluesrecordedintheradiographsimmediately} aftertheprocedureswerecomparedwiththoserecordedin theradiographsobtainedafterconsolidation,andthe differ-enceswere calculated (Fig. 2). Similarly,thepatellar height indexusingtheBlackburne-Peelmethodandthesagittalslope ofthejointline(tibialslope)weremeasured.Thedifferences betweentheseanglesallowedustoconfirmwhethertherehad beenalossofthecorrectionachievedbythesurgical proce-dure.Unionoftheosteotomysiteprogressesovertimefrom lateraltomedialanditwasjudgedaccordingtothepresence oftrabecularbonecrossingtheinitialgapduringfollow-upAP radiographicassessments.

Statisticalanalysis

Thepairedt-testwasusedtocomparepatellarheight,tibial slope, and varus correction postoperatively and after con-solidationbecause itconsiders groupedresponses, andthe assumptionofindependencebetweentheobservationswas

notadequate.StatisticalanalysiswasperformedusingSAS® 9.2software.

Results

Ofthe54patientswhounderwentsurgeryduringthisperiod, threewerelosttothe2-yearfollow-upandwerethusexcluded. Therefore,thefinalsampleincluded51patientswho under-wentopeningwedgeosteotomytocorrectvarusdeformityin theproximalendofthetibia, withfixationusinga4.5-mm largefragmentDCPplate.Autogenousbonegraftingharvested fromiliaccrestwasdoneonlyinninecases.Casedistribution according tothedegreeofarthrosis(Ahlbäck classification) is shown inTable 1. Inthis series of cases,three patients exhibitedfixationfailurewithlooseningofimplantsandloss ofcorrection.Theyreceivedfixationwithfixed-angleplates andprogressedwithadequateconsolidationandcorrection. Onepatienthadahematomainthesurgicalsitethatrequired surgicaldrainageandthatsubsequentlyresolved.At1year postoperatively,allosteotomieswereconsolidated.Nocases ofinfection,thromboembolicevents,orneurovascular com-plicationswerereported.

Table2summarizesthefindingsofthepresentstudy.There wasnoclinicallysignificantdifferenceintheassessed param-etersbetweenthepostoperativeradiographsandradiographs obtainedaftertheconsolidationoftheosteotomies.Changes in patellar height determined using the Blackburne-Peel

Table1–Distributionofpatientsaccordingtomodified Ahlbäckclassification.

Ahlbäck n

1 21

2 12

3 12

Table2–Differencesinthethreeassessedparametersbetweenradiographsobtainedimmediatelyaftertheprocedures andthoseobtainedafterosteotomyconsolidation.

Meandifference Standarddeviation Confidenceinterval(95%) p-Value

Lossofvaruscorrection 0.92 1.34 0.54–1.30 <0.01

Lossoftibialslope 0.27 0.75 0.06–0.49 0.01

Lossofpatellarheight 0.01 0.06 −0.01–0.03 0.29

method,tibialslope,andtibialcorrectioninthe anteroposte-riorplanewerenotsignificantandwerewithinthevariability expectedfor this typeofdimension. Thedifference inthe proximaltibialanglewasstatisticallysignificant.Themean correctionlossangle,whichwascalculatedbythedifference betweenthecorrectionangleintheimmediatepostoperative periodandafterconsolidation,was0.92◦_±0.9◦_.

Discussion

Themaincontributionofthepresentstudy wasto demon-strate that conventional and less expensive implants may provideadequatestabilityforacommonlyperformed proce-dureinactivepatientswithkneeosteoarthritis.Althoughthe numberofosteotomiesforthetreatmentofmedial gonarthro-sishasdecreasedovertheyearsinfavorofarthroplasties,this procedure isstillwidelyperformed. It improvessymptoms and functional capacityand allowsa delay inarthroplasty in a large number of patients.12 _{Several factors are} asso-ciatedwiththe successorfailure ofosteotomies;however, correctionmaintenanceisundoubtedly importantfor long-termoutcomes.13 _{Thetypeoffixationandselectedimplant} have a decisive role in the stability of the fixation. More-over, the small surface ofbone contact in opening wedge osteotomyleadstoahigherincidenceofcomplications.4,14 Nelissenetal.14_{studiedfixationusingshortplateswith} retrac-torsandreportedahigherrateofcomplicationsincasesin whichmoreextensivecorrectionswereperformed.Withthe adventofimplantswithlockingscrews,whichprovideangular stabilitytotheplate,thepopularityofthistypeoffixation sig-nificantlyincreased.8,15,16_{Biomechanicalstudiesconfirmthat} implantswithlockingscrewsenhancethestabilityofthe fix-ationofopeningwedgeosteotomies.15,17_{However,thehigher} costoftheseimplantslimitstheirroutineuseineconomically lessdevelopedcountries.Moreover,importantchangesmay occurinthesagittalplaneandpatellarheight,dependingon theosteotomytechniqueused.18_{Changesinthesagittalslope} ofthetibialplateauandpotentialreductioninpatellarheight afteranopeningwedgeosteotomyintheproximalendofthe tibiamayleadtosignificantbiomechanicalchangesthatcan compromiselong-termoutcomes.19

Themainfindingsofthepresent studyshowedthatthe osteotomytechniqueandfixationmethodwithconventional platesandscrews(whichareintheorylessstable)usedinour hospitalprovidedenoughstabilitytomaintainthecorrection achieveduntilconsolidationbecausethedifferencesobserved intheassessedparameterswerenotsignificant.Therewereno clinicallyrelevantchangesinthefrontalplane,sagittalplane, orpatellarheightwiththefixationmethod.Theuseofalateral spongiousscrewcrossingtheosteotomymayhaveprovided morestabilitytothefixation.Arecentbiomechanicalstudy

conductedatourhospitalshowedthatthe additionofthis screw,eveninthepresenceofagapinthelateralcortex,makes the resistancetothe fixationgapcomparabletothatofan intactlateralcortex.20

Althoughthestudyhadlimitations,suchasthe method-ologicallimitationinherenttoastudyofcasesandtheabsence of a comparison with other methods of fixation, the dif-ferences observed between the measured angles were not clinicallyorstatisticallysignificant,whichallowedusto con-cludethattheconventionalplatesandscrewsusedwiththe described techniqueprovidedenoughstabilityforthistype offixation. Theseimplants canstill beusedinthe clinical routine,withtheadvantageofbeinganaffordablesolution.

Conclusions

Theuseofconventionalplatesandscrewsisviableinthe fix-ation ofopeningwedgehightibialosteotomybecausethey provideenoughstabilitytomaintainthecorrectionachieved untilconsolidation,withoutsignificantchanges.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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