Rev. bras. ortop. vol.51 número1

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

Original

Article

Assessment

of

spontaneous

correction

of

lumbar

curve

after

fusion

of

the

main

thoracic

in

Lenke

1 adolescent

idiopathic

scoliosis

夽

Danilo

Mizusaki

∗

_,

_Alberto

_Ofenhejm

_Gotfryd

IrmandadedaSantaCasadaMisericórdiadeSantos,Santos,SP,Brazil

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received17December2014 Accepted23March2015 Availableonline13January2016

Keywords:

Scoliosis Bonescrews Treatmentoutcome

a

b

s

t

r

a

c

t

Objective:To evaluate the clinicalandradiographic responseof the lumbarcurve after fusionofthemainthoracic,inpatientswithadolescentidiopathicscoliosisofLenketype1.

Methods:Forty-twopatientswithLenke1adolescentidiopathicscoliosiswhounderwent operationsviatheposteriorroutewithpediclescrewswereprospectivelyevaluated.Clinical measurements(sizeofthehumpandtranslationofthetrunkinthecoronalplane,bymeans ofaplumbline)andradiographicmeasurements(Cobbangle,distallevelofarthrodesis, translation ofthelumbarapicalvertebralandRisser)weremade.Theevaluationswere performedpreoperatively,immediatelypostoperativelyandtwoyearsaftersurgery.

Results:ThemeanCobbangleofthemainthoraciccurvewasfoundtohavebeencorrected by68.9%andthelumbarcurveby57.1%.Eightypercentofthepatientspresentedimproved coronaltrunkbalancetwoyearsaftersurgery.Infourpatients,worseningoftheplumb linemeasurementswasobserved,buttherewasnoneedforsurgicalintervention.Less satisfactoryresultswereobservedinpatientswithlumbarmodifierB.

Conclusions: InLenke1patients,fusionofthethoraciccurvealoneprovidedspontaneous correctionofthe lumbarcurve andledtotrunkbalance.Lesssatisfactoryresultswere observedincurveswithlumbarmodifierB,andthismayberelatedtoovercorrectionof themainthoraciccurve.

Avaliac¸ão

da

correc¸ão

espontânea

da

curva

lombar

após

a

fusão

da

torácica

principal

na

escoliose

idiopática

do

adolescente

Lenke

1

Palavras-chave:

Escoliose

r

e

s

u

m

o

Objetivo:Avaliararespostaclínicaeradiográficadacurvalombarapósafusãodatorácica principal,empacientescomescolioseidiopáticadoadolescente(EIA)Lenke1.

夽

WorkperformedintheSpineGroup,DepartmentofOrthopedicsandTraumatology,SantaCasadaMisericórdiadeSantos,Santos,SP, Brazil.

∗ _{Corresponding}_author_.

E-mail:dan.mzk@gmail.com(D.Mizusaki).

http://dx.doi.org/10.1016/j.rboe.2015.03.013

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Parafusosósseos Resultadodetratamento

Métodos: Foramavaliadosprospectivamente42pacientesportadoresdeEIAtipoLenke1 operadospor viaposteriorcomparafusospediculares.Fizeram-semensuraçõesclínicas (tamanhodagibaetranslaçãodotronconoplanocoronalpelofiodeprumo)eradiográficas (ângulodeCobb,níveldistaldaartrodese,translaçãodavértebraapicallombareRisser).As avaliaçõesforamfeitasnopré-operatório,pós-operatórioimediato(POI)edoisanosapósa cirurgia.

Resultados: Foiobservadacorrec¸ãode68,9%,emmédia,doângulodeCobbdacurvatorácica principal(TPR)e57,1%dalombar.Oitentaporcentodospacientesapresentarammelhora doequilíbriocoronaldotronco,doisanosapósacirurgia.Emquatropacientesfoiobservada pioradosvaloresdamedidadofiodeprumo,sem,entretanto,havernecessidadedenova intervenc¸ãocirúrgica.Osresultadosmenossatisfatóriosforamobservadosempacientes commodificadorlombarB.

Conclusões:EmpacientesLenke1,afusãoexclusivadacurvatorácicaproporcionoucorreção espontâneadacurvalombarecompensaçãodotronco.Osresultadosmenossatisfatórios foram observadosem curvascommodificador lombarBe podem estarrelacionados à hipercorreçãodacurvatorácicaprincipal.

Introduction

Incasesofadolescentidiopathicscoliosis,theaimof surgi-caltreatmentistoprovidecompensationforthetrunkand vertebralfusionforcurvaturethatisconsideredtobe struc-tured.Forthis,thecurvatureisdeterminedinaccordancewith thepreoperativeradiographicflexibility,andthisguidesthe planningofthelevelsthataretoundergoarthrodesis.King etal.1_introduced_the_concept_of_selective_thoracic_arthrodesis

incasesthatwerenamed“falsedoublecurves”.Thisconcept hasbeenrefinedoverrecentdecades,especiallyconsequent tothepaperpublishedbyRichardsin1992.2

In2001,Lenkeetal.3_published_a_{two-dimensional}

classifi-cationofadolescentidiopathicscoliosis.Inthis,thecurvature isgroupedintosixmaintypesandisalsodescribedinterms oflumbarandsagittalmodifiers.LenketypeIisthemost fre-quentclassification,andthisonlypresentsstructuringofthe mainthoraciccurve (TPR). Thereisa consensusinthe lit-eraturethattype1Acurvatureshouldonlyreceivefusionof themainthoraciccurve.However,intypesBandC_, inclu-sionofthelumbarcurvature(TL/L)isamatterofcontroversy. Moreover, with the evolution of operative techniques and instrumentsthathavegreatercorrectivepower,ithasbeen observedthatgreaterinteresthasbeentakeninidentifying factorsthatpredictequilibriumoriatrogenicdecompensation ofthetrunkafterselectivefusionofthespine.

Theobjectiveofthepresentstudywastoevaluatethe clin-icalandradiographiccorrectionoflumbarcurvatureandits predictivefactors,afteronlyperformingfusionofthethoracic curveinpatientswithLenke1adolescentidiopathicscoliosis.

Materials

and

methods

Thisstudywasapprovedbytheinstitutionalresearchethics committee of the Catholic University of Santos (UNISAN-TOS)underthenumberCAAE31602014.4.0000.5536.Forty-two patientswithadolescentidiopathicscoliosispresenting cur-vaturegreater than 40◦ _who _underwent _spinal _arthrodesis

participatedinthisstudy.Theywereevaluatedclinicallyand radiographicallyinaprospectivemanner:beforethe opera-tion,immediatelyaftertheoperation(10daysafterwards)and aftertwoyearsoffollowup.Allthepatientswereoperatedby thesameseniorsurgeon.Theclinicalandradiographic evalu-ationswereperformedbymembersofthemedicalteamwho didnothavedirectparticipationintheresearch.

Thefollowingindividualswereconsideredtobewithinthe inclusioncriteria:bothgenders;thosewithLenketype1 ado-lescentidiopathicscoliosis;thoseoperatedbetweentheages of11and18years;thosewithCobbanglesbetween40◦ _and 90◦4_;_and_those_who_underwent_arthrodesis_of_the_main

tho-racicspinebymeansofaposterioraccessroute,usingpedicle screws.Patientswhorequiredpreoperativetractionordistal fusionatL1andthosewhosedatawereincompletelyfilledout wereexcluded.

Theclassificationofthecurvesfollowedthecriteria pro-posedbyLenkeetal.3_In_this,_the_curves_were_classified_into

sixmaintypes,accordingtotheirstructuring,andwerealso describedintermsofalumbarmodifier(relationshipbetween acentral-sacralverticallineandthelumbarapicalvertebra) andasagittalmodifier(kyphosisbetweenT5andT12).

CorrectionoftheTPRfollowedtheprinciplesofderotation oftheconcavitywitharodbymeansofthetechniqueofCotrel andDubousset.5_This_method_was_used_in_cases_with_lumbar

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curvewasused,inordertominimizetheriskofiatrogenic decompensationofthetrunk.

ThecriteriaofSuketal.6_were_used_to_determine_the_fusion

level.Thus, whenadifference ofup totwolevels between theneutralvertebraandtheterminalvertebrawasobserved, fusionwasperformedasfarastheneutralvertebraandwhen thisdifferencewithgreaterthantwolevels,fusionwasdone as far as one vertebra before the neutral vertebra. Radio-graphsoftheentirespinewereproducedonpanoramicfilm (90cm×30cm),inanteroposteriorview(AP),lateralview(P) andactivesupinelateralobliqueanteroposteriorview.7 _The

followingparameterswere evaluated aspossiblepredictive factors for trunkcompensation: Cobb angles of the proxi-malthoraciccurve(TPX),TPRandTL/L4_;_Risser_sign8_;_distal

levelofthearthrodesis;andtranslationofthelumbarapical vertebra.9_The_percentage_correction_of_the_curves_was

calcu-latedinaccordancewiththeformulaproposedbySuketal.6_:

Cobb pré-operatório−Cobb pós-operatório

Cobb pré-operatório ×100

Preoperative Cobb−postoperativeCobb

Preoperative Cobb ×100

Afterthis,ratiobetweentheCobbangleofthemain tho-raciccurvatureandthethoracolumbar/lumbarcurvaturewas calculated.

Theclinical measurementscomprisedthetranslation of thetrunkinthecoronalplane,measuredusingaplumbline (ScoliosisResearchSociety)10_and_the_size_of_the_lumbar_hump

(cm).Thesemeasurementsweremadeduringamaneuverof anteriorinclinationofthetrunk.11

Statisticalanalysis

Thepatients’qualitativecharacteristicswereevaluatedand weredescribedusingabsoluteandrelativefrequencies.Their quantitativecharacteristics were described using summary measurements(mean,standarddeviation,median,minimum andmaximum).

Thepreoperativeandpostoperativescalesweredescribed usingsummarymeasurementsandwerecomparedbetween the timesusing paired Wilcoxon tests.12 _The_scales

evalu-atedbefore the operation, inthe immediatepostoperative periodandtwoyearsaftertheoperationweredescribedand comparedusingFriedman tests,12 _followed_by_the _multiple

nonparametric comparisonsforpaired datathat were pro-posedbyNetteretal.13

Spearmancorrelationswerecalculatedbetweenthescales relatingtotwoyearsaftertheoperationinordertoascertain correlationsinthefinalresultsfromthepatients,betweenthe scales.12

Measurements oftrunk equilibriumusing a plumb line weredescribed,alongwiththoracolumbar/lumbarCobbangle values.Afterthis,thesevalueswerecorrelatedwiththedistal anatomicallevelofthearthrodesis(instrumenteddistal verte-bra),bymeansoftheMann–Whitneytest.12_The_preoperative

andpostoperativeplumblinevaluesandthescaleofplumb linechangeswerecomparedwiththethreetypesoflumbar modifiersofLenkeetal.,bymeansoftheKruskal–Wallistest.12

Thetestswereperformedwithasignificancelevelof5%.

Results

Amongthe42patientsincludedinthisstudy,4(9.5%)were maleand38(90.5%)werefemale;55%presentedtype4Risser signatthetimeofthesurgery.Theirmeanagewas11.9years and61.9%presentedlumbarAmodifier,33.3%presentedBand 4.8%presentedC.TheinstrumenteddistalvertebrawasT12 in23.9%andL1in76.1%(Table1).

ThemeanCobbangleoftheTPXwas24.69◦_(SD_7.34)_and thelateralinclinationwas13.07(SD7.56).Intheimmediate postoperativeperiod,themeanTPXcurvaturewas12.57(SD 6.84)anditwas12.64(SD6.89)twoyearsafterthesurgery.A meancorrectionof48.8%wasobserved.

Forthemainthoraciccurvature(TPR)beforetheoperation, themeanwas58.10◦_(SD_9.23)_and_the_lateral_inclination_was 29.07◦_(SD_11.32)._In_the_immediate_{postoperative}_period,_the meanvalueobservedwas15.90◦_(SD_6.46),_while_it_was_18.02◦ (SD6.91)twoyearsaftertheprocedure,i.e.animprovement of68.9%.

The thoracolumbar/lumbarcurvature (TL/L) presenteda meanof34.57◦ _(SD_9.18)_before_the_operation,_with_a_lateral inclinationof8.07◦_(SD_11.09)._In_the_immediate_{postoperative} period,thevalueobservedwas12.05◦_(SD_8.36)_and_after_two

Table1–Generalcharacteristicsofthesample.

Variable Description(n=42)

Sex,n(%)

Male 4(9.5)

Female 38(90.5)

Ageattimeofdiagnosis(years)

mean(SD) 11.95(1.13)

median(min;max) 12(11;15)

Risser,n(%)

1 3(7.1)

2 4(9.5)

3 10(23.8)

4 23(54.8)

5 2(4.8)

Lenke,n(%)

A 26(61.9)

B 14(33.3)

C 2(4.8)

Arthrodesislevel,n(%)

FinishedatL1 32(76.1)

FinishedatT12 10(23.9)

Proximalthoraciclateralinclination

mean(SD) 13.07(7.56)

median(min;max) 13(−6;24)

Mainthoraciclateralinclination

mean(SD) 29.07(11.32)

median(min;max) 30(6;56)

Thoracolumbar/lumbarlateralinclination

mean(SD) 1.43(11.09)

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Table2–Resultsfromtestscomparingbeforeandaftertheoperation.

Variable Time Mean SD Median Minimum Maximum N p

Hump(cm) Before 2.23 0.92 2 0 4 42 <0.001a

After 0.85 0.80 0.5 0 3 42

Plumb Before 1.25 1.23 1 0 5 42 <0.001a

After 0.25 0.59 0 0 3 42

CobbAPproximalthoraciccurve Before 24.69 7.34 24.5 12 45 42 <0.001 Immediatelyafter 12.57 6.84 10.5 2 32 42

Twoyearsafter 12.64 6.89 10.5 2 30 42

CobbAPmainthoraciccurve Before 58.10 9.23 58 44 91 42 <0.001 Immediatelyafter 15.90 6.46 15.5 1 28 42

Twoyearsafter 18.02 6.91 18 4 35 42

CobbAPthoracolumbar/lumbarcurve Before 34.57 9.18 34 17 54 42 <0.001 Immediatelyafter 12.05 8.36 10 0 35 42

Twoyearsafter 14.81 8.91 14.5 0 35 42

Translationofthoracicapicalvertebra Before 49.83 16.49 50 17 95 42 <0.001 Immediatelyafter 11.36 6.95 10 2 33 42

Twoyearsafter 12.29 9.32 11 −4 45 41 Translationoflumbarapicalvertebra Before 12.63 10.39 13 −5 46 41 0.866

Immediatelyafter 12.59 10.87 11 −3 33 41 Twoyearsafter 13.32 12.47 8 0 47 41

Instrumenteddistalvertebrainclination Before 24.78 6.64 24 11 45 41 <0.001 Immediatelyafter 6.07 3.96 5 1 17 42

Twoyearsafter 6.54 4.31 6 0 18 41

Friedmantest.

a _Paired_Wilcoxon_test.

yearsitwas14.81(SD8.91),whichrepresentedspontaneous correctionofthelumbarcurvatureof57.1%.

Thepreoperativethoracichumpwas2.23cm(SD0.92)and it was 0.85cm (SD 0.80) two years after the operation, i.e. animprovementof 61.8%(p<0.001).The mean plumbline measurementwas1.25cm(SD1.23)beforetheoperationand 0.25cm(SD0.59)afterthesurgicalprocedure,i.e.an improve-mentof80%(p<0.001).

Thetranslationofthelumbarapicalvertebrawastheonly parameteranalyzedthatdidnotpresentanystatistically sig-nificantimprovement(p=0.866)(Table2).

Itwasobservedthattherewerestatisticallysignificant dif-ferencesfortheTPX,TPRandTL/Lcurvature,incomparing thepreandpostoperativevalues(p<0.001).TheTPRandTL/L

curvatures presentedangularworsening regardingthe val-uesobtainedintheimmediatepostoperativeperiodandtwo yearsaftertheoperation(p=0.006andp=0.005,respectively) (Table3).

Fourpatientspresentedworseningoftheirtrunk equilib-rium, as measured using a plumb line. Of these,two also presentedincreasedlumbarhumps.Thesecaseswere clas-sified as Lenke A (one patient) and B (three patients). A descriptionoftherelationshipbetweentrunkcompensation andthelumbarmodifierispresentedinTables4and5.

Alsoinrelationtoclinicalmeasurementsonthe lumbar hump,accordingtoeachsubtypeofthelumbarmodifier(A, BorC),weobservedthattherewasnostatisticaldifference betweenthegroups,aspresentedinTable6.

Table3–Comparisonsbetweentheevaluationtimes.

Variable Comparison Zvalue p

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Table4–ChangeinplumbaccordingtothelumbarmodifiersofLenkeetal.

Changeinplumb Lenke p

A B C Total

N % n % n % n %

Worsened 1 3.8 3 21.4 0 0.0 4 9.5 0.097

Nochange 4 15.4 4 28.6 1 50.0 9 21.4

Improved 21 80.8 7 50.0 1 50.0 29 69.0

Total 26 100 14 100 2 100 42 100

Kruskal–Wallistest.

Table5–Gradingofthechangestotheparameters evaluated.

Variable Description(n=42)

Changetohump

Worsened 2(4.8)

Improved0–25% 6(14.3)

Improved25–50% 8(19)

Improved>50% 26(61.9)

Changetoplumb

Worsened 4(9.5)

Nochange 9(21.4)

Improved 29(69)

ChangetoCobb(thoracolumbar/lumbar)

Worsened 1(2.4)

Improved0–25% 1(2.4)

Improved25–50% 14(33.3) Improved>50% 26(61.9)

RationmainCobb/thoracolumbar/lumbarCobb

>1 24(57.1)

Between1and0.5 16(38.1) Between0.5and0.25 1(2.4)

<0.25 1(2.4)

TherelationshipsoftheplumblineandtheCobbTL/Lwith thelast instrumentedvertebraare presentedinTable7.In this,it can beseen that the distallevel ofthe arthrodesis (T12orL10)didnotinfluencetheplumblinemeasurementsor theCobbthoracolumbar/lumbarangle(p=0.479andp=0.194, respectively).

Discussion

Theaimsofsurgicaltreatmentofadolescentidiopathic sco-liosisaretocorrectthedeformity,restoretrunkequilibrium

andimplementarthrodesisonthesmallestnumberofspinal segmentspossible.14

Selectivethoracicfusionforavoidingunnecessaryfusion offlexiblelumbarcurveswasdescribedbyKingetal.1

Sev-eralarticleshavedemonstratedacapacitytoaccommodate lumbarcurvatureinrelationtothoraciccurvature,with main-tenanceoftheoverallalignment.14–16_However,_in_some_cases,

theremaybeinsufficientaccommodationofthelumbarcurve andunsatisfactoryestheticresults.Theprognosticfactorsfor accommodationofthelumbarcurvaturearenotfully estab-lishedinthecurrentliterature.

Inthepresentstudy,aspontaneousreductionintheCobb angle ofthe lumbar curvature of 57% was observed. This valueissimilartowhatwasreportedbyLenkeetal.14 _and

was greater than what was described by Parisini et al.15

(54.8%) and Peelle (50%).16 _However, _it _was _observed _two

years afterthe operationthat therehad been a significant increase in the lumbar Cobb angle (p=0.005). This obser-vation is contrary to previous descriptions, in which the spontaneouslumbarcorrectionwasseentobedynamicand the improvement would occur within the first two years after the surgery.14,17,18 _However,_we _observed_that _despite

radiographicworsening,nosignificantclinicaldeterioration was observed.Thiscanbeexplainedbythe factthatthere was proportional accommodationofthe instrumentedTPR curve, which maintained the angular ratio between the curves.

Thetranslationoftheinstrumenteddistalvertebra meas-uresthedisplacementofthespinefromthemidline.Forthe lumbarspine,nostatisticaldifferencefrombeforetoafterthe surgerywasobserved.Thiscouldhavebeenexpected,given thatthemajorityofthecurvesincludedwereofLenketype AorBandpresentedlesscoronaltranslationduringthe pre-operativeperiod.Therefore,thesepresentedlesspotentialfor surgicalcorrection.

Table6–Descriptionofclinicalplumblinemeasurementsbeforeandaftertheoperation,inaccordancewithLenkeetal., andtheresultsfromcomparativetests.

Variable Lenke Mean SD Median Minimum Maximum N p

Plumbbefore A 1.52 1.35 1 0 5 26 0.093

B 0.71 0.87 0.5 0 2.5 14

C 1.50 0.71 1.5 1 2 2

Plumbafter A 0.19 0.43 0 0 2 26 0.604

B 0.32 0.82 0 0 3 14

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Table7–ComparisonbetweenlastinstrumentedvertebraandchangestoplumbandCobbTL/L.

Variable Arthrodesislevel p

FinishedatL1 FinishedatT12 Total

N % n % n %

Changetoplumb 0.479

Worsened 2 6.2 2 20.0 4 9.6

Nochange 5 15.7 1 10.0 6 14.2

Improved 25 78.1 7 70.0 32 76.2

Changetothoracolumbar/lumbarCobb 0.194

Worsened 0 0.0 1 10.0 1 2.3

Improved0–25% 1 3.1 0 0.0 1 2.3

Improved25–50% 9 28.1 4 40.0 13 31.1

Improved>50% 22 68.8 5 50.0 27 64.3

Total 32 100 10 100 42 100

Mann–Whitneytest.

Consideringtheclinicalalterationsinrelationtothesize ofthethoracichump,therewasareductionofapproximately 62%afterthesurgery.Sincenothoracoplastywasperformed, weattributetheclinicalimprovementtothecapacityforaxial correctionpresentedbythesurgicaltechniquethatwasused. However,thecorrectioninthisplanewasnottheaimofthe presentstudyanditmightbebetterexplainedthrough

com-putedtomographyevaluations.Regardingthelumbarhump,

althoughthe studiesavailableare limitedtothose compar-inganteriorandposterioraccessroutes,theresultsfromthe presentsampleweresimilartothoseofNewtonetal.19_(50%),

butwerelowerthanthoseofLiljenqvistetal.20_(63%).

Plumblinemeasurementsareanimportantparameterin surgicaltreatmentforadolescentidiopathicscoliosis.21_In_our

study,animprovementinthisparameterof80%wasobtained aftertheoperation,whichwasgreaterthanorsimilartowhat wasfound byParisiniet al.(52%±8.7)15 _and _by_Liljenqvist

etal.20_(77.7%)._However,_there_were_four_cases_in_which_there

wasaworseningofthecoronalequilibriumofthetrunk.Twoof thesepatientspresentedassociatedworseningofthethoracic hump.Amongthecasesinwhichtherewasclinicalworsening, threewereclassifiedashavinglumbarBmodifier.

AspreviouslydescribedbyLenkeetal.22_and_King_et_al.,1

choosingastablevertebraasthedistalfusionlevelprovided trunkequilibriuminmostcases. Inaddition, noclinicalor radiographicdifferenceswereobservedbetweenpatientsfor whomthe instrumenteddistalvertebrawasT12 andthose forwhomitwasL1.

AccordingtoBridwelletal.,23_the_derotation_maneuver_may

evolvetowarddecompensationofthecompensatorycurves. ThisisgenerallycausedbyovercorrectionoftheTPRand inca-pacityforlumbaraccommodation.Itcanbeexplainedbythe factthatcurveswithlumbartypeBmodifiersometimeshave behaviorsimilartothatoftypeC,14_which_may_not_be

recog-nizedbeforetheoperation.

Thestrongpointsofthepresentstudywerethatithada prospectivedesignandthat ahomogenousgroup ofLenke 1patientswas selected.However,thefactthatmostofthe patientsanalyzedwereclassifiedashavinglumbarA modi-fier,andmuchsmallernumbershadsubtypeBandespecially subtypeC,canbeconsideredtobealimitation.

Conclusion

1. Arthrodesisperformedsolelyonthemainthoracic curva-tureinLenke1patientsprovidedspontaneouscorrectionof thelumbarcurvatureandconsequentcoronalequilibrium ofthetrunk.

2. Theleastsatisfactoryresultswereobservedincaseswith lumbarBmodifierandthesemayhavebeenrelatedto over-correctionofthemainthoraciccurvature.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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