Rev. bras. ortop. vol.50 número5

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

Original

Article

Reproducibility

of

the

Tronzo

and

AO

classifications

for

transtrochanteric

fractures

夽

Carlos

Augusto

Mattos,

Alexandre

Atsushi

Koza

Jesus,

Michelle

dos

Santos

Floter,

Luccas

Franco

Bettencourt

Nunes

∗

_,

_Bárbara

_de

_Baptista

_Sanches,

_José

_Luís

_Amim

_Zabeu

HospitaleMaternidadeCelsoPierro,PontifíciaUniversidadeCatólicadeCampinas(PUC-Campinas),Campinas,SP,Brazil

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Articlehistory:

Received6August2014 Accepted23September2014 Availableonline15August2015

Keywords:

Hipfractures Femoralneck

fractures/classification Testreproducibility

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Objective:To analyze the reproducibility of the Tronzo and AO classifications for transtrochantericfractures.

Method:Thiswasacross-sectionalstudyinwhichtheintraobserverandinterobserver con-cordancebetweentworeadingsmadeby11observerswasanalyzed.Theanalysisofthe variationsusedthekappastatisticalmethod.

Results:ModerateconcordancewasfoundinrelationtotheAOclassification,whileslight concordancewasfoundfortheTronzoclassification.

Conclusion: ThisstudyfoundthattheAO/Asifclassificationfortranstrochantericpresented greaterintraandinterobserverreproducibilityandthatgreaterconcordancewascorrelated withgreaterexperienceoftheobservers.Withoutdivisionintosubgroups,theAO/Asif clas-sification wasshown,asdescribedintheliterature, tobeacceptable forclinicalusein relationtotranstrochantericfracturesofthefemur,althoughitdidnotshowabsolute con-cordance,giventhatitsconcordancelevelwasonlymoderate.Nonetheless,itsconcordance wasbetterthanthatoftheTronzoclassification.

Reprodutibilidade

das

classificac¸ões

de

Tronzo

e

AO

para

fraturas

transtrocanterianas

Palavras-chave:

Fraturasdoquadril Fraturasdocolo femoral/classificac¸ão Reprodutibilidadedostestes

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e

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u

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o

Objetivo:Analisar a reprodutibilidade das classificac¸ões AO e de Tronzo para fraturas transtrocanterianas.

Método:Estudotransversalqueanalisouaconcordânciaentreduasleiturasfeitaspor11 observadores,intraobservadoreseinterobservadores.Aanálisedasvariac¸õesusouométodo estatísticoKappa.

夽

WorkperformedintheOrthopedicsandTraumatologyService,HospitaleMaternidadeCelsoPierro(PUC-Campinas),Campinas,SP, Brazil.

∗ _{Corresponding}_author_.

E-mails:[email protected],[email protected](L.F.B.Nunes).

http://dx.doi.org/10.1016/j.rboe.2015.08.002

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Resultados: Verificou-se concordância moderada para a classificac¸ão AO enquanto a classificac¸ãoTronzomostrouconcordâncialeve.

Conclusão: Otrabalhoevidencioumaiorreprodutibilidadeda classificaçãoAO/Asifinter eintraobservadorparaasfraturastranstrocanterianasdefêmur,oquetemrelaçãocom oaumentoda predominânciade concordânciacomaexperiência dosobservadores. A classificaçãoAO/Asifsemdivisãoemsubgruposmostrou-se,assimcomodescritona liter-atura,aceitaparaousoclíniconasfraturastranstrocanterianasdefêmur.Noentanto,não mostrouconcordânciaabsoluta,umavezqueseuníveldeconcordânciaéapenasmoderado, massuperiorquandocomparadacomaclassificaçãoTronzo.

Introduction

Transtrochantericfracturesareextracapsularandare charac-terizedasoccurringintheareabetweenthegreaterandlesser trochantersofthefemur.1_This_area_of_the_femur_is predomi-nantlyspongyandvascularized.

Elderlypatientsaremorevulnerabletothis typeof frac-turebecauseoftheirbonefragility.Inthesepatients,falling tothegroundisarelativelycommonmechanism.1,2 _In sur-veysconducted between1941and 1971 thatwere cited by DeLee,3_it_was_noted_that_patients_with_{transtrochanteric} frac-tureswereonaverage10–12yearsolderthan patientswith fracturesofthefemoralneck(whichareintracapsular),with ameanbetween66and76years.Itwasalsonotedthatcases amongfemalespredominatedovercasesamongmales,with ratiosof2:1–8:1.

Transtrochantericfracturesalsoaffectyoungadults, espe-cially through mechanisms of high-energy trauma.1 _The incidenceofthesefracturesisincreasing,alongwiththecosts involvedintreatingthem.InBrazil,inasurveyconductedby theMinistryofHealth,itwasobservedthat90%ofthe finan-cialresourcesdestinedfororthopedicdiseasesareconsumed byninediseases,andtranstrochantericfractureswereoneof these.4

Another problem that is faced is that one-third of the patients diewithin the first year afterthe injury and that approximately50%ofthepatientsbecauseincapableof walk-ingaloneorgoingupstairs,and20%requirefull-timehome care.5

Theprincipalmethodforpreciselydeterminingthe diagno-sisofthesefracturesisradiography,butshorteningofthelimb anditspositioninginexternalrotationareimportantclinical findingsthatcorroboratethediagnosisofthistypeofinjury.6 Thetreatmentissurgicalandinvolves useofplates witha sliding screw,cephalomedullarynails or fixed-angleplates, withaviewtoachievingpatientrehabilitationasquicklyas possible.6

Thereareseveralclassificationsystemsfor transtrochan-tericfractures.However,themaincharacteristicofa classi-fication system isthat it should containvalid information that helps to describe the nature of the fracture, such as topography,configurationofthefracture,degreeofstability and severity.Another characteristicisthatit shouldaid in planningforosteosynthesisandinpredictingtheprognosis

afterdefinitivesynthesis,withtheobjectiveofachieving sta-bleanatomicalprimaryreduction.2,7_It_is_also_important_that anyclassificationsystemshouldbereproduciblebetween dif-ferentobserversandalsobythesameobserverondifferent occasions.7

TheTronzoclassificationfortranstrochantericfractures8 wascreated in1974andisstillonethesystemsmostused today.ItwasbasedontheclassificationofBoydandGriffin,9 whoclassifiedfracturesaccordingtothepossibilityof achiev-ing and maintainingreduction(fourtypes: I–stableintwo parts;II_–_unstable_and_comminutive;III_–_unstable_and_reverse oblique;andIV–_{intertrochanteric–subtrochanteric}_with_two fractureplanes).In1949,Evans7_classified_fractures_after sur-gicaltreatmentasstableorunstable.

Tronzo8 ₍_Fig. ₁₎ _modified _the _{classification} _of _Boyd _and Griffin,9_and_this_resulted_in_five_types._This_{classification} sys-temisgreatlyusedtoday.

The AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification10,11_was_initially_created_by_Müller_et_al.10_in_the 1980sandhasperiodicallyundergoneupdateswiththeaimof standardizingtheclassificationoffracturesforworldwide cov-erage,throughasystemforlocatingtheboneandthetypeof involvement(letterandnumber),suchthatanalphanumeric code would makeit possiblefor professionalsto promptly know what hadhappened, whichwould facilitate commu-nication between orthopedicservices. For this reason, this systemistheonecurrentlymostusedinstudies.Inthis sys-tem,trochantericfracturesarerepresentedbycode31-A.They aresubdividedintothreegroupsbaseontheobliquityofthe fracturelineandthedegreeofdamage(bonefragmentation).11 Group1presentsafracturelinethatstartsinanyregion ofthegreatertrochanterandextendsasfarasapointabove orbelowthelessertrochanter.Thereareonlytwofragments andthemedialcortexisfracturedinonlyonelocality.These fracturesarestableafterreductionandfixation,sincethereis goodcontactbetweenthefragments,withoutboneloss.The lessertrochanterisintact.11

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Fig.1–Tronzoclassification.

Group 3 presents a fracture line that crosses the intertrochantericregion,abovethelessertrochantermedially andbelowthecrestofthevastuslateralisinthelateralregion. Thelineaffectsbothcorticesandhasthecharacteristicsof reverseobliquity.3

Thisclassificationalsodividesthegroupsintothree sub-groups,butinthepresentstudy,onlythegroups31-A1,31-A2 and31-A3(Fig.2)areused,giventhatfracturesofthesame subgrouppresentsimilarbiomechanicalbehavior.

The objective of this study was to evaluate the repro-ducibilityoftheAO/ASIFclassificationwithoutdivisioninto subgroupsandtheTronzoclassification,fortranstrochanteric fractures,bymeansofconcordanceanalysisbetweenpairsof readingsmadebyobserversatdifferentstagesoftraining.

Materials

and

methods

Fiftypreoperativeradiographsinanteroposterior(AP)and lat-eral views on patients with diagnoses oftranstrochanteric fracturesofthefemurthatoccurredbetweenJanuary2012and December2012wereselected.Alloftheseindividualswere skeletallymature(overtheageof20years).

Patients with previous pathological conditions in their limbsthat possiblymodified the normalanatomy, such as previousfracturesinthecoxofemoralregion,malformations, infections and bone tumors were excluded from the case selection.Fromthesedata, amultiple-choicequestionnaire

Table1–Classificationofthestrengthofconcordance accordingtothekappacoefficient.

Kappacoefficient Strengthofconcordance

Lessthanzero Poor

0.00–0.20 Negligible

0.21–0.40 Low

0.41–0.60 Moderate

0.61–0.80 High

0.81–1.00 Almostperfect

Table2–Kappaindex,standarderrorandconcordance betweenthetworeadingsatdifferenttimes,fortheAO classification.

Comparisonbetween thereadings

Kappa SE Concordance

O1Avs.O1B 0.71 0.09 High

O2Avs.O2B 0.48 0.12 Moderate

O3Avs.O3B 0.13 0.11 Negligible

O6Avs.O6B 0.24 0.08 Low

O10Avs.O10B 0.71 0.09 High

O11Avs.O11B 0.64 0.10 High

O1toO11,observers;A,firstreading;B,secondreading;SE,standard error.

wasformulatedinordertoclassifythefracturesaccordingto theAOsystem(31.A1,31.A2and31.A3,withoutthesubgroups ofeachdivision)(Table1)andaccordingtotheclassification ofTronzo(1973)8₍_Table₂_)._A_space_was_provided_below_each figureand,foreachcolumn,onlyoneresponsewastobe indi-cated.

Elevenphysicianswerechosen.Amongthese,threewere first-yearresidents,threewerethird-yearresidentsofa med-icalresidencyprogramonorthopedicsandtraumatology,two wereorthopedistswithspecialisttitleswithupto5yearsof experienceandthreewereorthopedistswithspecialisttitles withmorethan5yearsofexperience.Thesephysicianswere identifiedsequentiallywithnumbersfrom1to11.Allthe eval-uatorsworkedinthesame orthopedicsserviceatatrauma referral hospital.Theclassificationswere reviewedwith all the participants individually, before the questionnaire was applied.

The radiographs were analyzed independently, without contactbetweentheevaluators,underidenticalconditionsfor alloftheseobservers.Therewasnotimelimitforanswering thequestionnaire.

Onemonthlater,thesameobserversevaluatedthesame radiographs,without anyknowledgeofwhattheresponses theymadepreviouslywere,oranyknowledgeofthedatafrom theotherevaluators.Noneoftheobservershadaccesstothe datarelatingtothesurgicaltreatmentoneachfracture.

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Fig.2–AOclassificationaccordingtosubgroups.

observersbymeansofpairedanalyses.Theobserved propor-tionsofconcordancebetweentheobservers(Po)andwithin theobserverswerecompared.Thesevaluescouldvaryfroma resultoflessthan0(poor)to1(almostperfect).

Results

Theobservers analyzed 50 preoperative radiographs in AP andlateralviews,ontranstrochantericfracturesofthefemur andcategorizedthefracturesinaccordancewiththeAOand Tronzoclassifications.Eachobservermadetwoanalyseswith a1-monthintervalbetweenthem,withoutknowledgeofthe previous results and without priorcontact with the other observers.Theresultswereanalyzedbymeansofthekappa methodandtheresultsrelatingtothestrengthoftheintraand interobserver concordance were subdivided into six levels. Kappaindexvalueslessthan0wereclassifiedaspresenting poorstrengthofconcordance;valuesfrom0to0.2as negligi-ble;0.21to0.40aslow;0.41to0.60asmoderate;0.61to0.80as high;and0.81to1.0asalmostperfect.

Thepresentationofthekappaindex,standarderror(SE) and concordancebetweenthetworeadingsoftheAO/ASIF classificationmadebythe11observersattwodifferenttimes (Table2)showedthattheSErangedfrom0.9to1.2andthe kappaindexfrom0.13to0.77,withpredominanceinthe mod-eratetohighgroupofstrengthofconcordance(Fig.3).

Thepresentationofthekappaindex,SEandconcordance betweenthetworeadingsoftheTronzoclassificationmadeby

Kappa from AO classification

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Table3–Kappaindex,standarderrorandconcordance betweenthetworeadingsatdifferenttimes,forthe Tronzoclassification.

Comparisonbetween thereadings

O1Avs.O1B 0.26 0.08 Low

O3Avs.O3B – – NA

O6Avs.O6B 0.24 0.08 Low

O8Avs.O8B 0.22 0.08 Low

O9Avs.O9B – – NA

O10Avs.O10B 0.35 0.08 Low

O11Avs.O11B 0.26 0.08 Low

O1toO11,observers;A,firstreading;B,secondreading;SE,standard error.NA,notapplicablebecauseoftheasymmetryofthedata.

the11observersattwodifferenttimes(Table3)showedthat theSErangedfrom0.08to0.09andthekappaindexfrom0.22 to0.59.Twoobserverscouldnotbeincludedbecauseofgreat asymmetryofthe dataatthe two differentdata-gathering times.Thestrength ofconcordancewaspredominatelylow tomoderatefortheTronzoclassification(Fig.4).

The kappa index analysis comparing the two different readingsfortheAOandTronzoclassifications,madebythe observersatdifferenttimes,showedthatfortheAO classifi-cationthekappaindexwas0.53withSEof0.03,i.e.showing moderateconcordance.Ontheotherhand,theTronzo classifi-cationshowedakappaindexof0.36andSEof0.03,i.e.showing fairconcordance.

Theanalysis andcomparisonwere performedusingthe same statistical method, which correlated the observers accordingtotheirjobpositionsandexperience(Table4).Inthe analysisontheAOclassification,highkappaindexesand con-cordancewereseenamongthemoreexperiencedobservers, i.e.thosewithmorethan5yearssincecompletionof train-ing and those who had completed their training less than 5yearsago.Theobserverswhoweremedicalresidents pre-sentedlowervalues(Table4).

Thesameanalysisonthekappaindex,standarderrorand predominanceofconcordanceaccordingtojobpositionand experienceamongtheobserverswasperformedontheTronzo classification,asshowninTable5.

Kappa from Tronzo classification

Fig.4–Variationininterobserverkappaindexfromusing theTronzoclassification.

Table4–AOclassification,jobposition,kappaindex, standarderrorandconcordance.

Jobposition Comparison

betweenthe readings

S>5y O1Avs.O1B 0.71 0.09 High

S<5y O4Avs.O4B 0.77 0.08 High

S<5y O5Avs.O5B 0.65 0.1 High

R3 O10Avs.O10B 0.71 0.09 High

R3 O2Avs.O2B 0.48 0.12 Moderate

R1 O6Avs.O6B 0.24 0.08 Low

R1 O3Avs.O3B 0.13 0.11 Negligible

S>5y,specialistwithmorethan5yearsofexperiencesince train-ing;S<5y,specialist withlessthan5yearsofexperiencesince training.

R3,third-yearresident;R1,first-yearresident.

Discussion

Allfractureclassificationsystemshavetheobjectivesof guid-ingthetreatment,aidinginsurgicalplanningandhavingthe capacitytobereproducedwithhighconcordancebydifferent observersindifferentsituations.Thekappastatisticalsystem hasthecapabilitytonumericallytransmittherealcapacityof fractureclassificationsystems.

Schipperetal.12 _studied_the_AO_{classification}_system_for transtrochantericfracturesofthefemurusing20X-rayimages thatwereanalyzedby15observers.FromtheAOclassification withsubgroups, theyreportedamean intraobserver kappa

Table5–AnalysisontheTronzoclassificationsystemin relationtotheobservers’experience.

Jobposition Comparison

betweenthe readings

S>5y O1Avs.O1B 0.26 0.08 Low

S>5y O11Avs.O11B 0.26 0.08 Low

S>5y O7Avs.O7B 0.51 0.08 Moderate

S<5y O4Avs.O4B 0.55 0.08 Moderate

S<5y O5Avs.O5B 0.5 0.08 Moderate

R3 O10Avs.O10B 0.35 0.08 Low

R3 O8Avs.O8B 0.22 0.08 Low

R1 O9Avs.O9B – – NA*

R1 O6Avs.O6B 0.24 0.08 Low

R1 O3Avs.O3B – – NA*

R1 O3Avs.O3B 0.13 0.11 Negligible

S>5y,specialistwithmorethan5yearsofexperiencesince train-ing;S<5y,specialist withlessthan5yearsofexperiencesince training.

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indexvalueof0.48andaninterobservervalueof0.33.From theAOsystemwithoutsubgroups, theintraobserver kappa valuewas0.78andtheinterobservervaluewas0.67.A previ-ousstudyonfivepatientswithtranstrochantericfracturesof thefemuralsoconcludedthatusingtheAOclassificationwas unreliable.13

Neweyetal.14_reported_that_the_alphanumeric_system_of theAOclassificationwasunnecessarilycomplicatedandthat itsuseinclinicalpracticefellshortofwhatwouldbedesirable andmadelittlecontributiontowardsurgicalplanning.

AccordingtoPervezetal.,2_the_results_obtained_from_their studyconfirmedthatboththeAO/ASIFandtheJensen classi-ficationsystemwereunacceptable.

However,whentheAO/ASIFsystemwasdividedintoonly threegroups(31A1,31A2and31A3),itbecameacceptable.For thosewhofindthealphanumericterminologyconfusing, Per-vezetal.2_recommended_that_these_groups_should_be_named stabletrochantericfracture(31A1),unstabletrochanteric frac-ture(31A2)andtrochantericfracturewithreverseline(31A3). InastudythatcomparedtheAO/ASIFandJensen classi-fications,VanEmbdenetal.15_found_that_the_AO_system_had poorreliabilityandtheJensensystemhadmoderatereliability. Theyconcludedthattherewasaneedtocreateanew classi-ficationortoimprovetheexistingclassificationsinorderto achievebettercategorizationandtreatmentproposals.

Wedidnotfindanystudiesintheliteraturethatanalyzed thereproducibilityoftheTronzoclassification.

Wefoundthatthemeanintraobserverkappaindexforthe AOclassificationwas0.53(0.13–0.71),withpredominanceof moderatetohighconcordance.Therewasgreatinequalityin the analysisin relationtothe job positionand experience ofthe observer,such thathigh concordancepredominated amongtheprofessionalswhohadalreadyachievedthetitle ofspecialist, withakappaindexof0.696 (range:0.64–0.77) andstandarderrorof0.8–1.Inouranalysisontheresidents (bothatR1 and atR3 level), therewas lower concordance, suchthatthemean kappaindexwas0.4(range:0.13–0.71), withpredominanceoflowconcordanceandastandarderror of0.8–1.2.

ThemeanintraobserverkappaindexfortheTronzo clas-sificationwas0.31,withpredominance oflowtomoderate concordance.Ontheotherhand,inrelationtotheAO/ASIF system, comparison of the job position and experience of theobserversshowedthatthekappaindexwas0.416forthe observers who already had specialist titles, with predomi-nanceofmoderateconcordance,whilethekappaindexwas 0.23forthelessexperiencedobservers.Inthegroupofless experiencedobservers,itshouldbehighlightedthatthedata gatheredin relationto the Tronzo systemby twoof these observerscould notbeincluded intheanalysisbecause of greatasymmetryofthedatafromonereadingtotheother.

Conclusion

Wefound that higher concordance predominated inusing theAO/ASIFclassification,inrelationtotheTronzo classifi-cation,bothinintraandinterobservercomparisons.Wealso observedthat in relationto bothclassifications, therewas

higherconcordanceamongthemoreexperiencedobservers (physicianswithspecialisttitles)thanamongtheless experi-encedobservers(residents).

ThepredominantconcordancelevelintheAO/ASIFsystem withoutdivisionswasonlymoderate,andthiswas compat-ible withstudiesfoundinthe literature.In thecaseofthe Tronzoclassification,lowconcordancewasfoundto predom-inate. TheAO/ASIFclassificationsystem wascharacterized asacceptableforclinicalpractice,albeitimperfect,giventhe higherconcordanceamongobserverswithgreaterexperience.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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