Anterior fixation of odontoid fractures: results.

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SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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Original

Article

ﬁxation

of

odontoid

fractures:

results

夽

João

Pedro

Ferraz

Montenegro

Lobo

∗

,

Vitorino

Veludo

Moutinho,

António

Francisco

Martingo

Serdoura,

Carolina

Fernandes

Oliveira,

André

Rodrigues

Pinho

DepartmentofOrthopedics,SãoJoãoHospital,Porto,Portugal

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Articlehistory:

Received28February2017 Accepted10July2017

Availableonline14November2017

Keywords: Cervicalinjury Spinalfracture Fractureﬁxation Odontoidprocess Bonescrews

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Objective:Toevaluatetheclinicalandradiologicaloutcomesofthesurgicaltreatmentin patientsdiagnosedwithodontoid fracturewhounderwentopenreductionandinternal ﬁxation(ORIF)withscrews.

Methods:Thiswasaretrospectivestudywithninepatients.Pain(visualanalogscale[VAS]) andneurologicalstatus(Frankelscale)wereassessed.Theneckdisabilityindex(NDI)and thepost-operativecervicalrangeofmotionwerecalculated.Thecervicalspinewas radio-logicallyevaluated(X-rayandCT)pre-andpostoperatively.

Results:Themeanageofpatientswas70years.AllpatientspresentedtypeIIb(Grauer clas-siﬁcation)fractures,withameandeviationof2.95mm.Twopatientshadsubaxiallesions. Themeanfollow-upwas30months.Themeantimefromtraumatosurgerywassevendays. Thepre-operativeFrankelscorewasEinallexceptonepatient(B),inwhomapost-operative improvementfromBtoDwasobserved.Post-operativepainwas2/10(VAS).Atotalof77% ofpatientspresentedamildormoderatedisability(NDI).Sixpatientsregainedfullrange ofcervicalmovement,andboneunionrequiredapproximately14weeks.Pseudarthrosis complicationswereobservedintwopatients(77%unionrate),onepatientpresentedscrew repositioningandonecase,dysphonia.

Conclusion:Delayeddiagnosisisstillanissueinthetreatmentofodontoidfractures, espe-ciallyin elderly patients. Concomitantlesions, especially in youngerpatients, are not uncommon.TheliteraturepresentshighfusionrateswithORIF(≥80%),whichwasalso observedinthepresentstudy.However,surgicalsuccessdependsonproperpatient selec-tionandstrictknowledgeofthetechnique.Thispathologypresentsareservedfunctional prognosisinthemedium-term,especiallyintheelderly.

夽_Work_performed_in_the_Department_of_Orthopedics,_São_João_Hospital,_Porto,_Portugal. ∗ _{Corresponding}_author.

E-mail:joao2523@hotmail.com(J.P.Lobo). https://doi.org/10.1016/j.rboe.2017.07.010

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Fixac¸ão

de

fraturas

do

processo

odontoide:

resultados

Palavraschave: Lesãocervical Fraturaespinhal Fixac¸ãodecoluna Processoodontoide Parafusosósseos

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Objetivo: Avaliarosresultadosclínicoseradiológicosdotratamentocirúrgicoempacientes comdiagnósticodefraturadoprocessoodontoidesubmetidosareduçãoabertaefixação interna(RAFI)comparafusos.

Métodos: Estudoretrospectivocomnovepacientes.Avaliadaador(escalavisualanalógica [EVA])eoestadoneurológico(escaladeFrankel).ONeckDisabilityIndex(NDI)ea ampli-tudedemovimentocervicalpós-operatóriaforamcalculados.Acolunacervicalfoiavaliada radiologicamente(RaiosXeTC)nosperíodospré-epós-operatório.

Resultados: Aidademédiadospacientesfoide70anos.Todosospacientesapresentaram fraturasdotipoIIb(classificaçãodeGrauer),comdesviomédiode2,95mm.Doispacientes apresentaramlesõessubaxiais.Oseguimentomédiofoide30meses.Otempomédioentre traumaecirurgiafoidesetedias.Oescorepré-operatóriodeFrankelfoiEemtodos,exceto emumpaciente(B),noqualseobservouumamelhorapós-operatóriadeBparaD.Ador pós-operatóriafoi2/10(EVA).Umtotalde77%dospacientesapresentouincapacidadeleve oumoderada(NDI).Seispacientesrecuperaramtodaaamplitudedemovimentocervical;a consolidaçãoóssealevouaproximadamente14semanas.Foramobservadascomplicações depseudartroseemdoispacientes(taxadeconsolidação:77%),umpacientenecessitou reposicionamentodoparafusoeumpaciente,disfonia.

Conclusão: Odiagnósticotardioaindaéumproblemanotratamentodefraturasdo odon-toide,especialmenteem pacientesidosos. Aslesõesconcomitantes,especialmenteem pacientesmaisjovens,nãosãoincomuns.Aliteraturaapresentaaltastaxasdeconsolidac¸ão comRAFI(≥80%),oquetambémfoiobservadonopresenteestudo.Noentanto,osucesso cirúrgicodependedaselec¸ãoadequadadopacienteedoconhecimentorigorosodatécnica. Estapatologiaapresentaumprognósticofuncionalreservadonomédioprazo, especial-menteemidosos.

Introduction

Odontoid fractures comprise as many as 20% ofall cervi-calfractures.Theincidenceofodontoidfracturesincreases substantiallyinolderpatientsandrepresentsthemost com-moncervicalfracturesinpatientsolderthan70years.1_These

injuriesusuallyresultfromlow-energyimpactssuchasfallsin theelderlyorhigh-energyimpactssuchasmotorvehicle acci-dentsintheyoungandmiddleaged.2_Type_II_fractures_are_the

mostcommonodontoidfracture,occurringin65–74%ofthe cases.Thesefractureshavesimilarbiomechanicalproperties astransverseligamentinjuries,i.e.,alossofthetranslational restrictionofC1onC2,creatingthepotentialforspinalcord injuryandseverelatecraniocervicaldeformitieswhenhealing isnotobtained.3

Treatmentstrategiesforodontoidfracturescanvaryfrom conservativemanagement withanexternalimmobilization (such as a cervical collar, Minerva, and other cervicotho-racicorthoses,andhaloorthosis),tooperativemanagement with anterior odontoid screw ﬁxation (AOSF) or poste-rior cervical fusion with or without supplemental screw ﬁxation.1

Anterior screw ﬁxation of odontoid fractures was ﬁrst describedin1980byNakanishiandagainin1982inareport byBohlerbasedonan8-yearexperience.4_This_procedure_has

the potential advantageof preserving cervical motion and

generallyavoidstheneedforhaloimmobilization.Itis techni-callychallengingandhasbeenassociatedwithpseudarthrosis ratesofupto20%.4

Therehasnotbeenaclearconsensusamongtraumaspine surgeonsontheneedforoperationandtheidealtimingof suchﬁxationinpatientwithanodontoidfracture.Moreover, thechoiceofmanagement(operativevs.nonoperative, halo-vestimmobilizationvs.cervicalorthosis)hasbeenpostulated toinﬂuencemortality.Thehalovest,inparticular,hasbeen associatedwithanincreasedriskofcomplicationsanddeath inelderlypatients.5

The authors proposed to evaluate the clinical out-come,imagingandcomplicationsaftersurgicaltreatmentof patientsdiagnosedwithodontoidfractureundergoing reduc-tionandanteriorﬁxationwithscrewsduringtheperiodof1 January2009to31December2014.

Methods

Patientpopulation

Retrospectivestudy,overa6-yearperiod(2009–2014)with9 consecutive patients who underwent direct anterior screw ﬁxation in the context of C1–C2 instability Anderson and D’AlonzoTypeIIbodontoidfractures.Therewere7maleand 2femalepatientswhorangedinagefrom27to94years.

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Fig.1–ExamplesofpostopX-rays.

Clinicalandneuroimagingevaluation

Clinicalevaluationwasmadewithaminimumof2yearspost op.VisualanalogscalewasusedtoevaluatepainandFrankel scaleforneurologicalstatus.Neckdisabilityindexwasused toevaluatetheeffectofneckpainineverydaylife.A goniome-terwasusedforanalysesofpostopcervicalrangeofmotion (CROM).Allfractures were preoperativelyassessedby eval-uatingthe initialpreoperative lateral,AP and open mouth odontoidX-rayfilmsandCTscansoftheodontoid(withthe diameteroftheodontoidprocessinthecoronalplaneinthe regionoftransverseligamentoftheatlas).Serialpostoperative APandlateralflexion–extensionplainX-rayfilmsofthe cer-vicalspinewereobtainedtoevaluatefusionstatus(4weeks, 3and6months,1and2years). PostoperativeCTscanning wasalsousedtoaugmentplainX-rayfilmstudiesinsome cases.Anatomicalbonefusionwasconsideredsuccessfulif therewastrabeculationacrossthefracturesite,theabsenceof movementonlateralflexion–extensionradiographicstudies, andanatomicalalignmentofthefracturefragment.6

Operativetechnique

After general endotracheal anesthesia was induced, the patientwaspositionedsupineontheoperatingtable.X-ray fluoroscopy(2devices–AP/Openmouthviews+Lateralview) showedthefracturesanditsreduction.TheC5–C6diskspace wasidentifiedbymarkingthethyroidandcricoidcartilage pre-operatively,andthenaskinincisionwasmadebetweenthem. Thecarotidarterywaslaterallyretractedafterdissectingsoft tissuecarefully,andthetracheaandesophaguswere medi-allyretracted.Afterexposingtheanteriorcervicalspine,the antero-inferiormarginoftheC2bodywasexposed.Under flu-oroscopiccontrol,1or2Kirchnerwiresofappropriatelength wheretheninsertedfromtheanterioraspectoftheinferior margin ofC2, throughthe central axisof the dens, tothe opposingapicalcorticalbone.TheKirchnerwireswherethen

replacedbyoneortwoself-tapping3.5-mmscrewsof appro-priatelength(Fig.1).

Results

Nine patients who had type IIB odontoid fractures7 _were

treatedconsecutivelybyanteriorodontoidscrewfixation.No patientswere excludedbecauseofirreducibletypeIIb frac-tures. All patientswere treatedbyanterior odontoidscrew fixation,fourusingasinglecompressionscrewandfiveusing twoscrews.Thereweresevenmenandtwowomen,witha meanageof70years(range,27–94years)atthetimeofsurgery. The averagefollow-up was30 months.The mechanismof injurywasafallinsevenpatientsand motorvehiclecrash intwopatients.

Thediagnosiswasmadewithin24haftertraumainﬁve patients.Intheremainingfourpatient,thediagnosiswas ini-tiallyoverlookedandwaseventuallymadelater.Twopatients underwent operative ﬁxationwithin oneday ofthe injury, three days in one case, four days in one case, about one weekintreecaseandabouttwoweeksintwocases(Table1). Average time from traumatosurgerywas sevendays.The durationofsurgeryrangedbetween45minand90min.Two

Table1–Characterizationofpatients.

Sex Age Trauma/diagnosis Trauma/OOS

1 M 87 7Days 14Days

2 F 82 4Days 9Days

3 M 27 Sameday 3Days

6 M 83 5Days 13Days

7 F 94 7Days 8Days

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Table2–Characterizationoffractureandassociated injuries.

Type Displacement(mm) Angulation Otherinjuries

1 IIB 5 Posterior(30◦) – 2 IIB 4.5 Posterior(9◦) – 3 IIB 1.5 0◦ #C1,C6,C7 4 IIB 1.5 Posterior(5◦) – 5 IIB 5 Posterior(8◦) – 6 IIB 4 Posterior(4◦₎ _– 7 IIB 1 0 – 8 IIB 1 0 – 9 IIB 3 Posterior(7◦) C5–C6

Table3–Detailsofodontoidanatomy,surgical techniqueandfusionrate.

No. screws Transverse diameter (Dens) Entry point (mm)a Union (months) 1 1 7 Inferior(1.6) NU 2 1 7 Anterior(3.1) 3 3 2 8 Inferior(3) 6 4 2 8 Antero-inferiorcorner 3 5 2 10 Inferior(1) 3 6 2 7 Antero-inferiorcorner NU 7 1 7 Anterior(5.5) 6 8 1 7 Anterior(5.6) 3 9 2 8 Antero-inferiorcorner 3 NU,non-union.

a _Distance_(mm)_to_the_{antero-inferior}_corner_of_C2.

patientshadassociatedfracturesinthecervicalspine.Incase three,acombinedodontoidfractureand fractureofC1,C6, C7,andincaseninetherewasalsodiscoligamentarlesionof C5/C6.

The initial mean displacement was 2.95mm (range, 1–5mm). All fractures were displaced posteriorly (Table 2). Themeanvalueofthetransversediameteroftheodontoid was 7.6mm with minimum value of6mm and maximum of10mm.Threepatientshadananteriorentrypointofthe screwrelativetotheantero-inferiorcornerofC2(Table3).An anatomicreductionofthedenswasachievedinsevencases. Intwopatients,the densfragmentwasleftinslight poste-riordisplacement.Boneconsolidationaveragewas14weeks. Noradiographicsignsofboneconsolidationintwopatients (77%consolidation).Intermsofpostoperativecomplications thereweretwocasesofpseudarthrosis,onepatienthadscrew repositioningandonecaseofdysphonia.

Frankel classiﬁcation before surgery was grade E in all exceptonepatientwhohadgradeB.Postoperative improve-mentofpatient withthe gradeBto gradeDaftersurgery. Average values of post op pain where 2/10 (VAS). 44% of patients had a mild disability (NDI), 33% with moderate disabilityandonly1patientwithseveredisabilitywitha min-imumof2yearfollow-up.Sixpatientsregainedfullrangeof cervicalmovement.Threepatientslostbetween30%and50% ofneckrotationandonepatientexperiencedlimited move-mentinotherplanes(Table4).

Discussion

Smith,Vaccaroandcolleagues8_recently_reviewed_the_trends

inthesurgicalmanagementfortypeIIodontoidfractureat aregionalspinalcordinjurycenterandtheyconcludedthat themanagementoftypeIIodontoidfracturesinthe octoge-narianpopulationareassociatedwithsubstantialmorbidity andmortality,irrespectiveofthemanagementmethod.Our studywasmostlycomposedofelderlypatientsandourclinical resultsshowthatmostpatientsdidnotcomplainofneckpain (VAS2/10),nopatientsufferedneurologicimpairmentbutonly 1patient(≈11.1%)hadnodisability(NDI)afteraminimumof 2yearfollowup.

Theoretically,thisoperativetechniquedoesnotlimitneck rotation, although somerecent studies show that there is somerestrictionofmovement inatleastoneplane9 _has_it

wasshowninourstudy(Table4).

Intheseriespublishedintheliteratureofpatients under-goinganteriorﬁxationofodontoidfracturestypeIIandtype III,theaveragefusionrateis80%.Therisksassociatedwith anteriorﬁxationofodontoidwithscrewsaredirectlyrelated totheindicationsandsurgicaltechniques.9,10

Three basic requirements are needed forthe patient to beconsidered agood candidateforanterior ﬁxationofthe odontoid.Theﬁrstistheintegrityofthetransverseatlantal ligament,thesecondrequirementisthegoodreductionofthe fractureandalignmentofthefragmentsandthethirdisthe typeoffracture.10–12

Ingeneral,mostofthecomplicationsarerelatedto incom-plete fracture reduction with persistence of the posterior angulationofthefractureorincorrectlocationofthescrew insertionwhenmistakenlyplacedintheanteriorportionC2 body,insteadofbeingintroducedinthelowerportion.11

In thisstudy mostpatients were old (≥65 years)and in contrasttotheyoungerpopulation,themechanismofinjury tendstowardlow-energytraumasuchassimplefalls.Thisis inpartbecausecorticalandcancellousportionsofthedens becomesigniﬁcantlylessrobustwithage.13_The_low-energy

mechanismofinjuryandabsenceofsevereneckpainat pre-sentationincreasestheriskofdelayeddiagnosis.10 _Usually,

delayedfracture reductioncannotbeeasilyachievedinthe caseofdelayeddiagnosisandthepossibilityofnon-unionis relativelyhigh(2casesofnon-unionwithmorethan13days postinjury).

The entry point of the screw is an aspect ofthe tech-niquethatispoorlydescribed.Theapicalcortexisthedensest areaandforthisreasonitisessentialthattheﬁxationscrew fullyintegratesthecortexandthereforeaprecisetrajectory isrequired(lowercervicalarea).10_In_our_study_three_patients

hadananteriorentrypoint,withnodifferenceinunionrate comparedwiththeothers.

Thetransversediameterofthedensisthesmallest diame-terandisthecriticaldiameterfortheplacementoftwoscrews astheyareplacedsidebysideinthecoronalorthetransverse plane.Initially,itwasrecommendedusingthetwoscrew tech-niqueconsideringthatitwouldprovidesuperiormechanical stability.Odontoiddiametersofsomeindividualsmaynotbe largeenough toaccommodatetwo3.5-mm corticalscrews. The diameter of the patients odontoid in this study was

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Table4–Cervicalrangeofmotion.

Flexion Extension Leftlatﬂex. Rightlatﬂex. Leftrotation Rightrotation

Normal 50◦ 60◦ 45◦ 45◦ 80◦ 80◦ 1 20◦ 35◦ N N 45◦ 60◦ 2 N N N N N N 3 N N N N N N 4 N N N N 66◦ 60◦ 5 N N N N N N 6 N N N N 40◦ ₄₀◦ 7 N N N N N N 8 N N N N N N 9 N N N N N N

measuredwithcervicalCTandin4/9wecouldonlyplaceone screwsafely.Therewerenodifferencesintheunionrate com-paredwith2screwfixation.Two-screwfixationprovidesbetter stabilityinrotationandextensioncomparedwithonescrew, buttherearenosignificantdifferencesintheunionrateinthe literature.14

Conclusion

Delayed diagnosis is still a handicap in the treatment of odontoidfracturesandshouldalwaysbesuspectedinelderly patientswithneckpainafterfall.Itisnecessarytobeawareof thecombinationofconcomitantlesionsespeciallyinyounger patients.

ThetreatmentofacutefracturesoftheodontoidtypeIIB usinganteriorscrewﬁxationprovedtobeaneffectivemethod oftreatment.Bonefusionof77%iscomparedwithother stud-iesintheliterature.

Thesuccessofthistechniquedependsonproperpatient selection,technicalcareintheperioperativeperiod,the sur-geon’sexperienceandstrictknowledgeoftheindicationsand contraindicationsofthistechnique.Apartfromanyinternal orexternalfactorthispathologyhas(mainlyintheelderly)a reservedfunctionalprognosisinthemediumterm.

Conﬂicts

of

interest

Theauthorsdeclarenoconﬂictsofinterest.

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