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EOS analysis of lower extremity segmental torsion in children and young adults
E. Gaumétou, Sergio Quijano, Brice Ilharreborde, A. Presedo, Patricia Thoreux, Keyvan Mazda, Wafa Skalli
To cite this version:
E. Gaumétou, Sergio Quijano, Brice Ilharreborde, A. Presedo, Patricia Thoreux, et al.. EOS analysis
of lower extremity segmental torsion in children and young adults. Orthopaedics and Traumatology -
Surgery and Research, Elsevier, 2014, 100 (1), pp.147-151. �10.1016/j.otsr.2013.09.010�. �hal-03262729�
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Original article
EOS analysis of lower extremity segmental torsion in children and young adults
E. Gaumétou
a,∗, S. Quijano
b,2, B. Ilharreborde
a,1, A. Presedo
a,1, P. Thoreux
b,2, K. Mazda
a,1, W. Skalli
b,2aServicedechirurgieorthopédiquepédiatrique,universitéParis-Diderot,Paris7University,hôpitalRobert-Debré,AP–HP,48,boulevardSérurier,75019 Paris,France
bBiomechanicslaboratory,ArtsetMétiersParisTech,151,boulevarddel’Hôpital,75013Paris,France
a rt i c l e i n f o
Articlehistory:
Accepted13September2013
Keywords:
Femoraltorsioncourse Tibialtorsioncourse Lowerlimbtorsion EOS3Dreconstructions Skeletalimaging Child
a b s t r a c t
Introduction: Lowerlimbtorsionvariessubstantiallyamonghealthychildrenduringgrowth.Values reportedintheliteraturetodatehavebeenobtainedusingsemi-quantitativeclinicalor2Dmeasure- mentmethods.Quantitative3Dmeasurementwouldhelpdeterminethephysiologicalrangeoflower limbtorsion.Low-dosestereoradiographywith3Dreconstructionprovidesagoodalternative.Itsuse increasesinpediatricsbecauseofradiationminimization.Previousstudieshaveshownaccurateand reproducibleresultsoflowerlimbsreconstructioninadultsandchildrenbutthetorsionalparameters haven’tbeenmeasuredyet.Thepresentstudyreportsthevaluesoflowerlimbsegmentaltorsionandits courseduringgrowthinacohortofhealthychildrenandyoungadultsusingtheEOSlow-dosebiplanar X-ray.
Hypothesis: EOS3Dreconstructionisanaccurateandreproduciblemethodtomeasurethetorsional parametersinchildren.
Materialsandmethods:Femoraltorsion(FT)andtibialtorsion(TT)werestudiedon114volunteers(228 lowerlimbs)from6to30yearsofagedividedbyageinto5groups.TheEOSTMacquisitionswereobtained insubjectsstandingwiththeirfeetoffset.
Results:MeanFTdecreasedduringgrowth,passingfrom21.6◦to18◦,whereasmeanTTincreasedfrom 26.8◦to34.7◦.Therewasastatisticallysignificantdifferencebetweenthe2extremeagegroups,butno differencewasfoundbetweenanyotheragegroups.TheICCforintra-observerreproducibilitywas0.96 and0.95forFTandTTforthefirstoperator,and0.79and0.83forthesecondoperatorrespectively.The ICCforinter-observerreproducibilitywas0.84and0.82respectively.
Discussion:Thecourseoflowerlimbsegmentaltorsionobservedwasconsistentwithliteraturereports baseduponclinicaland2Dmeasurements.3DreconstructionofEOSlow-dosebiplanarimagingappears tobeasafeandreliabletoolforlowerlimbsmeasurements,especiallyforinvestigatinglowerlimb segmentaltorsioninchildrenandadults.
Levelofevidence:LevelIV.
©2013PublishedbyElsevierMassonSAS.
1. Introduction
Lowerlimbtorsionvariessubstantiallyamonghealthychildren duringgrowth.Femoraltorsionisin-between35◦–41◦atbirthand declinesgraduallyuntilreachingameanof12◦–15◦atadulthood.
Tibialtorsionisinternaltorsionatbirthchanginggraduallytoa
∗Correspondingauthor.Tel.:+33140033049;
fax:+33140032298;+33140032217.
E-mailaddresses:elodie.gaumetou@ensam.eu, elodie.gaumetou@rdb.aphp.fr(E.Gaumétou).
1Tel.:+33140032000;fax:+33140032298.
2Tel.:+33144246299.
meanof19◦ofexternaltorsionatadulthood,withgreatvariations [1].Disordersduringgrowthordiseasecanresultinmalalignment andlowerlimbtorsionalabnormalities.Thediagnosisandtreat- mentshouldbebasedonaccuratemeasurements[2].Rotational problemshaveoftenbeenignoredbecausebeingmoredifficultto measure thanfrontal-plane andsagittal-planedeformities[3,4].
Theonlypreviousliteraturevaluesofnormaltorsionalcoursewith growthweredeterminedusingsemi-quantitativeclinicalmeasure- ment methods[3,5–9].Radiographicmeasurementmethods are rarelyusedbecauseoftheircomplexityandlackofreproducibility [10–12].Computedtomography(CT)isthecurrentgoldstandard forquantitative3Dmeasurement,butitsuseislimited,particularly inchildren,becauseofionizingradiation[2,13–22].Theradiation exposure does not allow either repeated 3D examinations for 1877-0568/$–seefrontmatter©2013PublishedbyElsevierMassonSAS.
http://dx.doi.org/10.1016/j.otsr.2013.09.010
148 E.Gaumétouetal./Orthopaedics&Traumatology:Surgery&Research100(2014)147–151
follow-up,orfull-body3Dmodeling[23–25].Inaddition,CT-scan imaging is performed with the patient in a reclining position, whereinter-articularcompensationmechanismsarehardlymea- surable[26].Low-dosestereoradiographywith3Dreconstruction providesa fastandaccuratealternative, providing afull-length weight-bearingbiplanarX-rayinlessthan20seconds[4,26].Its useincreasesinpediatricsbecauseofX-raysexposure800to1000 timesinferiortoCT-scan[4,27–30].Publishedstudieshadshown accurateandreproducibleresultsoflowerlimbsreconstructionin adultsandchildren[25,26,31].Thetorsionalparametershaven’t beenstudiedyetinchildren.Thegoalofthisstudywastomeasure physiologicallowerlimbtorsionalvaluesandtheircourseduring growthinahealthypopulationofchildrenandyoungadultsusing EOSbiplanarX-rayswith3Dreconstruction.
WehypothesizedthatEOS3Dreconstructionisanaccurateway tomeasurethetorsionalparametersinchildren.
2. Materialandmethods 2.1. Radiologicalparameters
Theparametersdeterminedwerefemoraltorsion(FT)andtibial torsion(TT).Femoraltorsionisalsodesignatedfemoralantever- sion,i.e.theangular differencebetweentheaxisofthefemoral neckandthebicondylaraxisofthedistalfemur,bothprojectedon aplaneperpendiculartotheshaftaxis.Tibialtorsionistheangle betweentheproximaltibialbicondylaraxisandthebimalleolar axis,projectedonaplaneperpendiculartotheshaftaxis.
2.2. Patients
Thepopulationconsistedof114healthyvolunteers(228lower limbs), from6 to30 years old.Theyhave been dividedbyage into5groups,6–7years,8–9years,10–12years,13–15yearsand 16–30years.Allhadlow-dosebiplanarX-raysusingtheEOSsystem (EOSTMImaging, France).Thesedataacquisitionswerefromthe databaseoftheArtsetMétiers,ParisTech.Allpatientswereprospec- tivelyincludedafterIRBapproval.Alloftheselowerlimbswere asymptomatic.
2.3. Acquisitionsand3Dreconstructions
Acquisitions were performed according to the shifted-feet standingpositionprotocol,inwhichthepatientispositionedsoas
tosimplifytheprocessofbonystructuresrecognition[26].Three- dimensionalreconstructionswereperformedusingidefx4.8.4.The fast3Dreconstructionmethodwasutilizedwithrapidadjustments formeasurementoftorsion,previouslydescribedandvalidatedby Chaibiet.al.[26].Thismethodallowsobtaininga3Dsimplifiedper- sonalizedparametricmodel.Thenthemodelcouldbecorrectedto obtainafull3Dmorpho-realisticpersonalizedparametricmodelof thelowerlimb(Fig.1).Theclinicalmeasurementsareautomatically extractedfromthefinalenvelope.Thesamespecificallytrained operatorperformedall3Dreconstructions.Twostudieswereper- formed toassess operator qualification.The first one aimedat assessingtheintra-observerreproducibility.Tworeconstructions wereachievedbythefirstauthorin610-to12-year-oldsubjects.
Thesecondonewasconductedtovalidateinter-observerrepro- ducibility.Radiographsfrom12patients,randomlychoseninthe 6to12agecategory,werereconstructed3timesby2operators.
Amongthetwo operators,onewasseniorpediatricorthopaedic surgeons(operator1,whofollowedapracticalcoursewithexam- ination),andonewasexperiencedwiththemethod(operator2).
2.4. Statisticalanalysis
Studentt-testsandMann-Whitneytestswereusedtocompare subgroupvalues of FTand of TT.Thethresholdfor significance wasP<0.05.Inter-observerandintraoberverreproducibilitywas assessedbycomputingtheintraclasscorrelationcoefficient(ICC).
3. Results
TorsionalvaluesarereportedinTable1.Therewasastatistically significantdifferencebetweenthe2extremeagegroupsregarding bothparametersbutnodifferencewasfoundbetweenconsecutive agegroups.Duringgrowth,femoraltorsiondecreased(P=0.01)and tibialtorsionincreased(P=0.0006).Torsionalcourseisrepresented inFig.2.ThemeanFTinthewholepopulationofthisstudywas 18◦±9◦andmeanTTwas31◦±8◦.
Theresultsoftheintra-observerreproducibilitystudyshowed goodintra-observerreproducibilitywith2.9◦variationoffemoral torsion and 4.1◦ variation of tibial torsion. The ICC for the intra-observer reproducibility was0.96 and 0.95 for FT and TT respectivelyforthefirstoperator,and0.79and0.83respectively forthesecondoperator.TheICCforinter-observerreproducibility was0.84and0.82respectively.
Timereconstructionwasabout10minutesfor2lowerlimbs.
Fig.1. Differentstepsofthereconstructionmethod:a)biplanarX-raybefore3Dreconstruction;b)theoperatorwasaskedtoadjust3circlesrepresentingtheprojectionof thefemoralheadandthefemoralcondylesonbothX-rayradiographs.Thoseprojectionswereoptimizedbysemiautomaticidentificationofafewanatomicallandmarks, permittingcomputationofaninitialmodelthatwassuperimposedontheX-ray;c)furtheradjustmentsweremade,soastoadjustthecontourstotheanatomicallandmarks;
d)3Dlowerlimbobtainedwereautomaticallycalculated.
Table1
Torsionvaluesforeachgroupsofthestudy(degrees).
6–7years 8–9years 10–12years 13–15years 16–30years
Nlowerlimbs 34 22 96 32 44
Meanage 6.6 8.9 10.9 14.1 23.3
MeanFT±SD (Minima–Maxima)
21.6±10 (0.6–39.5)
19.4±6.4 (9.3–34)
19±9 (–2.8–38.7)
15.3±8 (4.9–40.4)
18±9.1 (0.2–36.8) MeanTT±SD
(Minima–Maxima)
26.8±6.6 (11.7–45)
25.9±6.7 (10.5–37.3)
29.6±6.3 (12.6–44.8)
32.8±8.3 (12.3–57.9)
34.7±7.8 (19.8–51.6) SD:standarddeviation;FT:femoraltorsion;TT:tibialtorsion.
Fig.2. Torsionalprofileevolutionwithgrowthforfemoraltorsion(FT)andtibial torsion(TT).
4. Discussion
Thevaluesoflowerlimbsegmentaltorsionduringthecourseof growthmeasuredinthepresentstudywiththisnewimagingtech- niqueareconsistentwiththeevolutionofthesevaluespreviously reportedintheliterature[3,5,6,8,9,11,32].
4.1. Femoraltorsion
The present study confirms the decrease in femoral torsion duringgrowth(Table2).Comparisonisdifficultbecauseofthedif- ferencesinradiographicprotocols(Tables2and3).UsingtheNetter techniqueofclinicalmeasurement[9,11]in1319healthyschool children,Jacquemieretal.[5]observedthatmeanFTrangedfrom
21◦at5yearsto9.5◦at10yearsofageinboys,andfrom37◦at5 yearsto16.7◦at10yearsofageingirls.Bedouelle[9]prospectively studiedthecourseofFTinchildrenanddescribedfourdifferent evolutiveprofiles,inthreeofwhichtorsionreversedspontaneously duringgrowth,twograduallyandonestepbystep.Fabryetal.[6]
reportedthecourseoffemoralanteversionin432healthychildren.
Using2Dradiologicalmeasurements,theyreportedameanantev- ersionof26.7◦ at5years,decreasingto15.3◦at16yearsofage.
CTorMRImeasurementshavebeenreportedonlyinadultsand sliceorientationforcalculating3Danglesisproblematicwiththese examinations[7,8,33].MeanFTrangedfrom10◦[33]to16◦[7,8]in thosestudies,findingsthatappearunderestimatedcomparedwith thepresentresults.
4.2. Tibialtorsion
Thecourseoftibialtorsionobservedinthepresentstudywas consistent with literature data showing that external rotation increaseswithageuntil13–15yearsandremainedintheranges observedindifferentpublications(Table3).Jacquemieretal.[5]
foundthatTT,definedastheanglebetweenthetransmalleolaraxis andthecoronalplane,wasrelativelystablewithanincreasefrom 35◦at5yearsto36◦at10yearsofage,inboththefemalesand males.However,usingtorsiometermeasurements,Hutchinsetal.
[34]observedanincreaseinTTof7◦inboysand4◦ingirlsbetween 5and25yearsofage.Stahelietal.[3]reportedasimilarincrease betweenbirthand10to15yearsofage.Atcompletionofgrowth, TTstabilizedatanaverageof23◦rangingfrom0◦to45◦,regardless oftheageinterval.Theyconfirmedthatthetightfootanglewasless accuratethanthetransmalleolaraxisbecauseoffootdeformities (hindfootvarusorvalgus,footadductionorabduction).Thewide rangeofvaluesfoundintheliteraturecanbepartlyexplainedby thevariousassessmentmethods[5],andalargeruseoflow-dose biplanarX-raymighteliminatethisbiasinthefuture.
4.3. Advantages
Theabilitytomeasuretheanatomicalparametersofthelower limbin3Disessentialintheanalysisoflowerlimb,diagnosisand preoperativeplanning.Thelow-dosestereographyisanaccurate
Table2
Comparisonwithliteraturevaluesforfemoraltorsion(indegrees).
FT Current
(EOS)
Jacquemier (Clin)
Fabry (X-rays)
Schneider (MRI)
Jend (CT)
Goutallier (CT)
Duparc (CT)
5years 21.6 21(M)/37(F) 26.7
7years 21.6 16(M)/31(F) 23.2
8years 19.4 12(M)/26.7(F) 21.3
10years 19 9.5(M)/16.7(F) 20.9
12years 19 19.9
13years 15.3 20
15years 15.3 15.4
16years 18 15.3
30years 18 10.4 15.2±12 15.3 16
M:male;F:female;Clin:clinical;FT:femoraltorsion.
150 E.Gaumétouetal./Orthopaedics&Traumatology:Surgery&Research100(2014)147–151
Table3
Comparisonwithliteraturevaluesfortibialtorsion(indegrees).
TT Current(EOS) Jacquemier (Clin)
Staheli (Clin)
Hutchins (Clin)
Schneider (MRI)
Jend (CT)
Goutallier (CT)
Duparc (CT)
5years 26.8 35 12–20 10
7years 26.8 33 12–20
8years 25.9 34 20–25
10years 29.6 36 25–30
12years 29.6 25–30
13years 32.8 25–30
15years 32.8 25–30
16years 34.7 25–20
30years 34.7 23 17.4(M)/13.9(F) 41.7 40±9 24.9 27.7±11
M:male;F:female;Clin:clinical;TT:tibialtorsion.
method,reliable,inexpensive,reproducibleandthree-dimensional onsubjectsinphysiologicalstandingposition[4,25,26].Theradi- ation exposure is very limited, allowing its use for children follow-up.Themeasurementsmadeareindependentoftheposi- tionofthepatientinthecabinandoftheoperatorexperience.There isnomagnificationerror.Itallowsthevizualizationoftheentire limbandspineatthesametime.
4.4. Limitationsofthestudy
Onelimitationofthepresentstudywasthearbitrarychoiceof agegroups. Amore judiciouschoiceof agegroupsmight exist, and separation by gender might have been more enlightening.
Thepatientscouldalsohavebeenclassifiedaccordingtoskeletal maturity,forexampleusingRisserindex,whichiseasilyassessed withEOS.Futureprospectivelongitudinalstudiescouldclarifythe courseofFTandTTinrelationtoskeletalgrowth.
Thecurrentreconstructionmethodstillhassomelimitations, especiallyregardingyoungchildrenwithimmatureskeletons.As amatteroffact,thestatisticalmodelappliedtothechildinorder toobtainapatientspecific3Dreconstructionisderivedfroman
adultdatabase.Presedoetal.[31]investigatedthefeasibilityofthe EOStechniqueinchildren5yearsofageorolder,andreportedsome inaccuracyandlackofreproducibilityduetotheabsenceoffemoral headsphericityandtotheincompleteossificationoftheinternal malleolus,inthe6–7yeargroup(Figs.3and4).Thissuggeststhe needtofurtherdevelopthemodeltoextendreconstructions to specificanatomies.
ValidatingtheuseofEOSinchildrenwouldhaverequiredacom- parisonbetweentorsionalvaluesobtainedfromEOSandCT-Scans, butthedoseofirradiationdeliveredfortheCT-scanacquisitions precludesitsuseinyounghealthychildren.Thustheonlyalterna- tiveleftwascomparisonwithliteraturedata.
4.5. Reproducibility
Theresultsobtainedintheinter-intra-observerreproducibil- itystudyarewithinthemarginsofpreviouslypublishedvalues [26]. TheICCintra-observer for FTvaries in-between0.79–0.96 and0.83–0.95forTT,basedontheoperatorexperiencewiththe reconstructionmethod.TheICCinter-observerisconsistentwith thearticleofFolinaisetal.[35]whichobtainedaninter-observer
Fig.3. HipbiplanarX-rayat6years.Blackarrowsshowthezoneswithapoordefinition:thelessertrochanterisnotvisible,thefemoralheadisnotroundandthefemoral neckappearsthickerthannormal.
Fig.4.AnklebiplanarX-rayina6-year-oldchild.Blackarrowsshowthezoneswithapoordefinitionduetoincompleteossification.
ICCof0.94forFTand0.84forTT,inadults,onreconstructionsmade by3experiencedradiologists.Inthisstudy,theanatomicalland- marksidentificationdifficultiesforcalculatingFTandTTmayhave influencedtheresults.
Although the limitations previously mentioned, the EOS 3D reconstructionmethod basedonlow-dose biplanarX-rays pro- vidednormativedataoflowerlimbsegmentaltorsioninchildren andthecourseofFTandTTduringgrowth,thatcouldnotbeen obtainedtodate.Thelow-dosebiplanarX-rayisa goodwayto assess the segmental torsions since the clinical measurements obtainedwereconsistentwiththosefoundintheliterature,while greatlyreducingradiationexposure[25,35].Itprovidesacontrol databasethatcanserveforinvestigatingtorsionalabnormalitiesin variousdisorderssuchasleglengthdiscrepancies,cerebralpalsy orlowerlimbscongenitalpathologies.
Disclosureofinterest
Theauthorsdeclarethattheyhavenoconflictsofinterestcon- cerningthisarticle.
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