Rev. bras. ortop. vol.51 número4

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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

Original

Article

Is

the

size

of

the

acetabular

bone

lesion

a

predictive

factor

for

failure

in

revisions

of

total

hip

arthroplasty

using

an

impacted

allograft?

夽

Rodrigo

Pereira

Guimarães

_,

_Alexandre

_Maris

_Yonamine,

_Carlos

_Eduardo

_Nunes

_Faria,

Marco

Rudelli

FaculdadedeCiênciasMédicasdaSantaCasadeSãoPaulo,DepartamentodeOrtopediaeTraumatologia,GrupodoQuadril,SãoPaulo, SP,Brazil

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o

Articlehistory:

Received12August2015 Accepted25September2015 Availableonline27June2016

Keywords: Hiparthroplasty Bonetransplantation Acetabulum Allografts

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t

Objective:Theaimofthisstudywastodeterminetheacetabularbonelesionsize(in mil-limeters)fromwhichimpactedbonegraftfailurestartstooccurmorefrequently,through simpleanteroposteriorhipradiographs,andwhethermeasurementofthedefectonsimple radiographsmaintainsthesamepatternininterandintraobserverassessments.

Methods:Thirty-eight anteroposterior pelvic-viewradiographsfrompatientsundergoing revisionofanacetabularprosthesiswereretrospectivelyanalyzedandassessed.Inthe ver-ticalplane,thebilacrimallinewasmeasuredinmillimetersfromthefarthestpointfound ontheboneedgeoftheacetabularosteolysistothetopedgeofthecementationorofthe acetabularimplantinuncementedcases.Thebasewastakentobealineperpendicularto bilacrimalline,withtheaimofeliminatinganypelvictilteffects.Thismeasurementwas namedtheverticalsizeoffailure.Radiographsproducedfouryearsaftertheoperationwere analyzedtoinvestigateanyfailureofthetechnique.

Results:Thegraftfailurerateinthestudygroupwas26.3%.Thefailuresoccurredincases withaninitialbonedefectlargerthan11mm.Nocaseswithmeasurementssmallerthan thisevolvedwithfailureoftherevision.Thehighestincidenceofgraftfailureoccurredin casesdescribedasadvancedaccordingtothe“Paprosky”classification.

Conclusion:Failure of acetabular revisionarthroplasty using an impacted graft did not presentanystatisticallysignificant correlationwiththeverticalextentofthelesionon simpleanteroposteriorradiographs,asapredictoroftreatmentfailure.

©2016PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradeOrtopedia eTraumatologia.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).

夽

StudyconductedattheFaculdadedeCiênciasMédicasdaSantaCasadeMisericórdiadeSãoPaulo,DepartamentodeOrtopediae Traumatologia,GrupodoQuadril,SãoPaulo,SP,Brazil.

∗ _{Correspondingauthor.}

E-mail:clinicaguimaraes@gmail.com(R.P.Guimarães). http://dx.doi.org/10.1016/j.rboe.2015.09.015

O

tamanho

da

lesão

óssea

acetabular

é

fator

preditivo

para

a

falha

nas

revisões

de

artroplastia

total

do

quadril

com

enxerto

impactado?

Palavras-chave: Artroplastiadequadril Transplanteósseo Acetábulo Aloenxertos

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Objetivo: Opresentetrabalhobuscou,atravésdeumaradiografiasimplesanteroposterior doquadril,quantificaremmilímetrosapartirdequaltamanhodalesãoósseaacetabular ocorrecommaiorfrequênciafalhadoenxertoósseoimpactadoeseamedic¸ãododefeito nasradiografiassimplesmantémomesmopadrãonaavaliac¸ãointereintraobservador. Métodos: Foramanalisadaseaferidasretrospectivamente38radiografiasdepacientes sub-metidosàrevisãodepróteseacetabularnaincidênciaanteroposteriordebacia,mensurando emmilímetros,noplanoverticalalinhabilacrimal,amedidaentreopontomaisdistante encontradonabordaósseadaosteoliseacetabular,comamargemsuperiordacimentac¸ão ouimplanteacetabularnoscasosnãocimentados.Tomamoscomobaseumalinha perpen-dicularalinhabilacrimalcomointuitodeeliminarefeitosdeinclinac¸ãopelvic.Essamedida foidenominadaTamanhoVerticaldaFalha.Radiografiaspós-operatóriascomquatroanos foramanalisadasparaaveriguarfalhadatécnica.

Resultados: Nogrupoestudadoobservamos26,3%defalhasdoenxertoqueocorrerama partirde11mmdetamanhodafalhaósseainicialmensuradaequeabaixodessevalor nenhumcasoevoluiucomfalhadarevisão.Amaiorincidênciadafalhadoenxertoocorreu noscasosavanc¸adossegundoaclassificac¸ãodePaprosky.

Conclusão: Afalhanaartroplastiaderevisãoacetabularcomenxertoimpactadoquando relacionadoàmedidaverticaldalesãoemradiografiasimplesanteroposteriordoquadril nãoapresentousignificânciaestatísticacomofatorpreditivodefalhadotratamento.

©2016PublicadoporElsevierEditoraLtda.emnomedeSociedadeBrasileirade OrtopediaeTraumatologia.Este ´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

The consolidation of contemporary total hip arthroplasty techniqueshasresultedinanincreaseintheuseofthis pro-cedure.Therefore,theneedforrevisionsurgeryhasbecomea morecommonproblem.1

The restoration of the anatomy and biomechanics improvesdurabilityandfunctionoftherevisedhip.Themost challengingaspectofacetabularrevisionistocompensatefor acetabularbonelossandcreateastablereconstruction,with goodlongtermdurability.2

Various techniques are described to rebuild extensive acetabular defects, including structural grafts or impacted graftchips,reinforcementringswithcages,placementofthe acetabularcomponentinahighhipcenter,jumboacetabular cups,bilobedacetabularcups,triflangecups,andtrabecular metalacetabularaugments.2

Although more modern prosthesis revision techniques areavailable,associatedwithnewimplants,thisprocedure remainsachallenge,evenformoreexperiencedsurgeons.3

Thelooseningofcementedorcementlesscomponentsin totalhiparthroplastyisalwaysaccompaniedbylossofbone stock.Sloofetal.4_{proposedtheuseofimpactedbonegraftin}

revisionsofthiscomponentwhenbonelosswassignificant. Acetabularreconstructionwithimpactedbonegraftanda cementedcupisareliabletechnique,withaten-yearsurvival rateof 88% inpatients withextensive acetabulardefects.2

BonelosscanbedeterminedbytheclassificationofPaprosky etal.,5_{whichprovidesasimplealgorithmtodeterminebone}

defectand directtreatmentforrevisionintotalhip arthro-plasty.

Brownetal.,6 _{inastudythatusedthePaprosky}

classifi-cation,demonstratedaninterobserverreliabilityof0.61.This indicatesasubstantialagreementamongsurgeons.The intra-observerreliabilityforeachofthefoursurgeonsinthatstudy was 0.81, 0.78, 0.76, and 0.75, which indicates substantial agreement.

Thisstudyaimedtoassesswhetheracetabularboneloss, measuredinasimpleanteroposteriorradiographofthepelvis, isapredictivefactorforfailureintherevisiontechniquewith impactedbonegraft,andwhether themeasurementofthe defectinplainradiographsmaintainsthesame patternfor inter-andintraobserverassessments.

Material

and

methods

This study was approved by the Research Ethics Commit-tee,underCAEENo.07779812.6.0000.5479.Postoperativepelvic radiographs of 38 patients undergoing revision surgeryfor total hip arthroplastieswere assessed;these patientswere operatedonbythreeexperiencedhipsurgeonsbetween1995 and2008.

Line A (bilacrimal)

Line B

Point C

Point D

Fig.1–HipX-rayinanteroposteriorincidenceshowing

measurementofthesizeofbonedefectinmillimetersin

theverticalplane;thismeasurementcorrespondstothe

greatestdistancebetweentheedgeoftheacetabularlesion

(pointC)andtheacetabularroofinitsanatomicalposition

(pointD).

publishedstandardsbythehipgroup:patientinthesupineor standingposition;rayincidenceonthemedianline, imme-diately above the pubic symphysis, feet internally rotated at15–20◦_{whenpossible(forcorrectionoftheneck} antever-sion angle),so that the greater trochanter didnot overlap thefemoralneck;and thecoccyx shouldbevisualizedand alignedwiththepubicsymphysis,withacranialdistanceof 2.5cminfemalesand1.5cminmales.Theobturatorforamen shouldbesymmetrical.7_{Allradiographsstudiedwere}

analogi-cal,withmagnificationof100%.Casesofsepticlooseningwere excluded.

AftertheselectionofX-rays,theacetabularcomponentof theprosthesiswasanalyzedandthebonelosspriortothe reviewwasclassifiedusingthePaproskymethod.Thebone defectwasmeasuredinmillimeters.Themeasurementwas madebythreeorthopedists:eachmadetwoassessments,with anintervalofoneweek.

Bonelosswasmeasuredasfollows:inthehipradiography inanteroposteriorincidence,thebilacrimallinewasdrawn (lineA).Next,lineBwasdrawnperpendiculartolineA,ina paththatincludedmostoftheacetabularfailuretobestudied, andtwopointswereset(C_{andD).PointCcorrespondedto} theupperedgeoftheacetabularfailure,andpointD,tothe topedgeoftheacetabularcementoroftheacetabularcup incementlesscases. ThedistancebetweenpointsC andD wasmeasuredinmillimetersandtermedverticalsizeofthe acetabularfailure(Fig.1).

Subsequently, radiographs were analyzed after a mean of 48 months follow-up and it was determined whether or notloosening ofthe revised acetabularcomponent had taken place. Treatment failurewas defined asa change of theacetabularcomponentposition,steepening,ormigration higherthan2mmwhencomparingX-rayintheimmediate postoperativeperiodwithafinal radiograph.8 _Furthermore,

thepresenceofsolid radiolucentlineslargerthan 2mmor

progressionofradiolucentlinesaroundtheacetabulumalso characterizedtreatmentfailure.9

The reliability ofthe inter- and intraobserver measure-ment wasindicatedbytheintraclasscorrelationcoefficient (ICC).Nextstepconsistedincomparingwhetherornotthe implant loosened withthe sizeofacetabularfailure, using theMann–Whitneynon-parametricmethod.Inaddition,the samemethodwasusedtocomparefailurevs.ageandfailure vs.gender.Inallstatisticaltests,a5%significancelevelwas adopted.Todeterminewhetherthemethodusedwasa pre-dictivefactorforfailureoftheproposedtreatment,anROC curvewasused.

Results

Forthepresentstudy,38patients(38hips)wereselected:mean ageof60.5years(range29–87years),23females(60.5%)and15 males(39.5%).Ofthese,13hadinvolvementontherightside (34.2%)and25ontheleftside(65.8%).

According tothePaproskyclassification,twohips (5.3%) wereclassifiedastype1;nine(23.7%)as2A;eight(21.1%)as 2B;six(15.8%)as2C;ten(26.3%)as3A;andthree(7.9%)as3B. Regarding thetypeofsurgerythesepatientsunderwent, 33werefirstrevisionarthroplasties(86.8%),fourweresecond revisionarthroplasties(10.5%),andonewasathirdrevision arthroplasty(2.6%).Theprimarycauseofarthroplastieswas alsoanalyzed:14hipshadprimaryosteoarthritis(36.8%),eight had inflammatorydisease(21.1%),sixhadtraumasequelae (15.8%),fivehadmalformation(13.2%),andfivehadavascular necrosisofthefemoralhead(13.2%).

Failureintheproposedtreatmentwasobservedintenhips (26.3%):threefailureswereobservedintheavascularnecrosis ofthefemoralheadgroup(30%),threeintheinflammatory diseasesgroup(30%),twointheprimaryosteoarthritisgroup (20%),andtwointhehipmalformationgroup(20%).

Failureintheproposedtreatmentwas relatedtogender andsidewithinthetenpatientswithfailureafterreview,six ofwhomweremale(60%ofthefailures)andfourfemale(40% ofthefailures);threeontherightside(34.2%ofthefailures) andsevenontheleft(65.8%ofthefailures).

Therelationshipoflooseningormigrationofthe acetabu-larcomponentwiththePaproskyclassificationindicatedthat therewere nofailuresinhips classifiedasPaprosky1,two failuresinhipsclassifiedas2A(20%),nofailuresinthose clas-sifiedas2B,twofailuresinthoseclassifiedas2C(20%),sixin thoseclassifiedas3A(60%),andnofailuresinthoseclassified as3B.

Failureoftheproposedtreatmentwascomparedwiththe typeofsurgerythatthesepatientshadundergone:eight fail-ures (80%) were observed in patients who underwent first revisionarthroplasty,onefailure(10%)inapatientwho under-wentsecondrevisionarthroplasty,andone(10%)inthesingle patientwhounderwentthirdrevisionarthroplasty.

Thesizeoftheinitialbonelesionrangedfrom3to37mm; inthisstudy,patientswhosebonelesionsweresmallerthan 11mm did not present failure of the proposed treatment (Fig.2).

40.00

32

30.00

20.00

10.00

0.00

Failure No failure

Failure of the acetabular component

ABC Summary

Fig.2–Boxplotcomparingfailureoftheacetabular

componentvs.sizeofinitialbonelesion.

40

32

12

32 32

30

20

10

0

Exc_mm Exb_mm

Exa_mm

Fig.3–Boxplotcomparingmeasurementsperformedby

evaluatorsvs.sizeoftheinitialboneinjury.

inter-observeragreement(ICC>0.70)betweenthe measure-mentsoftheverticalsizeofthefailure,demonstratingthe reliabilityofthemethod(Fig.3).

Discussion

Acetabular bone deficiency may be caused by wear, loos-ening, infection,bonelossatthe time ofprevioussurgery, pre-existing fracture, acetabular dysplasia, or even bone destructionduringremovalofthecomponentorcement.All thesefactorsleadtobonedeficiency,whichhinderstreatment. Totalhiparthroplastyrevisionsareoftenassociatedwith lossofacetabularbonestock.4_{Intheliterature,thereare}

var-ioustreatmentsto managethis problem, but none isfully effective.Treatmentaimstoprovidestabilityoftheimplant andrestorethejointcenterofrotation.10

Theselesionscanbetreatedwithbonegraftingorlarger prostheses, according to the techniques described in the

literature.2,11 _{Thebone grafts used for revision}

arthroplas-ties have been an important object of study for some authors,1–4,11–14_{withgrowingexpectationsofsolvinga}

prob-lemthathasnodefinitivesolutionyet.

Thehomograftusedforacetabularreconstructioncanbe dividedintotwogroups:blockgraftandgraftchips.Theuseof blockgraftiscontroversial10,11_{andusuallyrestrictedtocases}

withextendedacetabularfailure.12,13_{Theuseofthisgraftto}

fillthebonedefecthasbeenlinkedtoearlyfailureduetograft absorptionand fracture,especiallywhenusedasasupport system.14

In recent studies, Hooten et al.15,16 _{have shown that}

althoughradiographicallytheautologousgraftappearstobe integratedandabsorptionareasarenotobserved,therefore indicatinganapparentstabilityoftheacetabularcomponent, postmortemhistologicalexamsrevealedvascularizationonly onthe surfaceofthe graftincontactwithhostbone.Only peripheralintegrationwasobserved,tonomorethan2mm, making thegraftanavascularmasswithoutany chanceof integration.

Theliteratureshowsthatgraftfailureratesincreasewhen usingstructuredgraftstosupportareaslargerthan50%ofthe acetabularcomponentsurface.15_{However,aspreviously}

men-tioned,themainindicationforblockgraftsarebonedefects ofgreatermagnitude,inwhichover50%ofthesurfaceofthe acetabularcupissupportedbyfreshbonegraft.15

Inarecentstudy,Bilgen etal.3 _{concludedthathavingat}

least50%contactbetweentheacetabularcup andthehost boneisnotabsolutelynecessaryforastableconstruction.

JastyandHarris17,18_{foundnodifferencesbetweentheuse}

ofautograftorhomograft,consideringbothformsofgraftto havesimilarefficacyforacetabularboneloss.

Sloofetal.4_{proposedtheuseofimpactedgraftchips;their}

techniquehasgained wideacceptanceand isusedin vari-ousservices.Theirstudyusedimpactedbonegraftchipsand obtained90%goodresultsinameanfollow-upof11.8years.

Buttaro et al.19 _{assessed23 revisions, appliedthe same}

techniquewithfrozengraft chipswithameanfollow-upof 35.8 months, and obtained 90.8% good results.In a recent study,Combaetal.20_{evaluated30cases,alsowithfrozengraft}

chips,withameanfollow-upof86.5monthsand86%good results.

Buckley et al.21 _{analyzed 123 acetabularrevision}

proce-duresusinggraftchipswithameanof60months,achieving 86%goodresults.Theintegrationofimpactedgraftchipshas alreadybeenreportedinstudieswithhistologicalanalysis.20

Theimpactedgraftchipstechniquewasappliedinallpatients inthepresentstudy.

vanHaarenetal.22_{reportedahighfailurerateof28%at7.8}

yearsoffollow-up,withtheuseofimpactedgraftsfordifferent magnitudesofacetabularfailure,includingpelvic discontinu-ity. However,theydidnotquantitativelyestablish towhich magnitudesofbonedefectimpactedgraftingiscorrectly indi-cated.

Inthepresentsample,similarresultswereobserved,with a26.3%incidenceofgraftfailureat48monthsfollow-upwith thetechniquepresentedfordifferenttypesofboneinjury.

Garcia-Cimbreloetal.23_{evaluatedtheacetabulargraft}

ROC curve

Specificity

-1 Specificity

-1

Sensitivity Sensitivity

1.0

0.8

0.6

0.4

0.2

0.0

1.0

0.8

0.6

0.4

0.2

0.0 1.0 0.8 0.6 0.4 0.2

0.0 0.0 0.2 0.4 0.6 0.8 1.0

ROC curve

Fig.4–ROCcurveshowingabsenceofstatisticalsignificanceinmeasurementoftheverticalsizeofthelesionvs.revision

failure.

initialboneloss; theyacknowledged the needforcages or platesinlargerlesions.However,thismagnitudewasalsonot quantified.Thepresentstudydidnotadoptseriouslesionsas anexclusioncriterion,preciselytoaddressthelackof infor-mationontheacceptabledegreeofacetabularbonestockloss forimpactedbonegraft.

El-Kawyetal.24_{evaluated28patientsclassifiedasPaprosky}

type3andfound96.4%goodresultsat72monthsoffollow-up. In the present study,the samplewas not largeenough tostatisticallycorrelatethePaproskyratingwith the num-ber of failures observed. The analysis of the ROC curve (Fig.4)shows that the verticalsizeofthe lesion isnot an implant failurepredictor (p>0.05). However,inasubjective analysisof the data, no revisionfailures were observed in lesionswithinitialverticalsizelowerthan11mm.Themain challenge inthis study wassurely tofind the best way to assessthemagnitudeofthislesionwithonlyanteroposterior X-rays.

Somelimitationsofthisstudyarenoteworthy.First,some studieshaveshownthesuperiorityofCTinrelationtoX-ray tomeasureacetabularpreoperativeboneloss.25,26 _However,

asthepresentanalysiswasretrospective,from1995to2008, thevastmajorityofpatientshadnodocumentedtomographic images.Thus, theanalysisofhip X-raysinanteroposterior incidencewasthemethodchosen.

Anotherlimitationofthestudywastheuseofasimple X-raytomeasureacavity.Itisknownthattheacetabularlesion isathree-dimensionalconditionandthatitsprecise measure-mentinonlyoneradiograph isnotpossible.However,this studyaimedtoevaluatethepossibilityofaquickandeasy study,whichcouldbedoneintheoffice,topredictapossible failure,aswellastoassesswhetherthemeasurementofthe verticalsizeofthelesiononsimpleradiographswassimilar intheinter-andintraobserverevaluation.

Inthiscase,astheradiographicevaluationpresenteda con-sistentinter-andintraobserveragreement,theauthorsbelieve thattheresultswerenotcompromised.

Finally, authors believe that studies with larger sample sizes are needed to better define the correlation of the

failureinthistypeoftreatmentwiththesizeofthe preop-erativebonelesionmeasuredinsimpleradiographs.

Conclusion

Failure in revision acetabular arthroplasty using impacted graftdidnotpresentastatisticallysignificantassociationwith variablesdescribedinthepresentstudy,demonstratingthat themeasureoffailureinananteroposteriorradiograph can-notbeusedinisolationasapredictivefactorforfailureofthe acetabularrevision,whichisconfirmedbylackofsignificance intheROCcurve.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

Acknowledgements

Theauthorswouldliketothankthesurgeons:Prof.Dr. Gian-carlo Cavalli Polesello, Dr Walter Ricioli Junior, Dr Marcelo CavalheirodeQueiroz,Prof.DrEmersonKiyoshiHonda,and Prof. Dr Nelson Keiske Ono, for performing surgeries and follow-upofpatientsanalyzedinthisstudy.

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