Rev. bras. ortop. vol.51 número4

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SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

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

Original

article

Prediction

of

flexor

tendon

graft

diameter

in

reconstruction

of

the

cruciate

ligament

by

means

of

magnetic

resonance

imaging

夽

Fabiano

Kupczik

a

_,

_Luiz

_Otávio

_Bombonatto

_Tauscheck

a,∗

_,

Marlus

Eduardo

Gunia

Schiavon

a

_,

_Bruno

_Sbrissia

a

_,

_Lucio

_Sergio

_Rocha

_Ernlund

b

_,

Ricardo

Augusto

Lass

Alves

a

a_Pontifícia_Universidade_Católica_do_Paraná_(PUC-PR),_Hospital_{Universitário}_Cajuru,_Curitiba,_PR,_Brazil b_Instituto_de_Joelho_e_Ombro,_Curitiba,_PR,_Brazil

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e

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n

f

o

Articlehistory:

Received15July2015 Accepted8September2015 Availableonline6June2016

Keywords:

Anteriorcruciateligament Anteriorcruciateligament reconstruction

Magneticresonancespectroscopy Orthopedicprocedures

a

b

s

t

r

a

c

t

Objective:Toevaluatethediameteroftheflexortendonsinpreoperativemagnetic reso-nanceimaging(MRI)examinationsandcomparethiswiththediameterofthegraftobtained intraoperatively.

Methods:Thiswasaretrospectivelongitudinalepidemiologicalstudy.Forty-fourpatients wereeligibleforthestudyandtheirMRIexaminationsandsurgicaldatawereevaluated. ThetendonsweremeasuredonMRIacrosstheirlargestdiameterintheaxialplane,usingthe medialepicondyleofthefemurastheslicelevel.Inthesurgery,routinegraftpreparation wasperformed,consistingoffoldingthegracilisandsemitendinosustendonstoforma four-strandgraft.Itsmeasurementwasrecorded.

Results:Toevaluatetheassociationbetweenthevariables,Pearson’scorrelationcoefficient wasestimated.Asignificantcorrelationwasfoundbetweenthemeasurementsofthe gra-cilisandsemitendinosustendonsandthefinaldiameterofthegraft(p<0.001).AROCcurve wasfittedtothesumofthetendondiametersinordertodetermineacutoffpointassociated withthegraftdiameter(≤8mmor>8mm).Ifthesumwasgreaterthan5.28mm,thechance ofobtainingagraftlargerthan8mmwouldbe75%.

Conclusion: Measurement ofthe diameters ofthe gracilis and semitendinosus tendons throughapreoperativeMRIexaminationisasimpleandeffectivewaytopredictthefinal sizeofthegrafttobeusedinACLreconstructionsurgery.

夽

StudyconductedatHospitalUniversitárioCajuru,PontifíciaUniversidadeCatólicadoParaná(PUC-PR),Curitiba,PR,Brazil. ∗ _{Corresponding}_author_.

E-mail:luizotaviobt@hotmail.com(L.O.B.Tauscheck). http://dx.doi.org/10.1016/j.rboe.2016.06.002

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Predic¸ão

do

diâmetro

do

enxerto

dos

tendões

flexores

na

reconstruc¸ão

do

ligamento

cruzado

por

meio

da

ressonância

nuclear

magnética

Palavras-chave:

Ligamentocruzadoanterior Reconstruc¸ãodoligamento cruzadoanterior

Espectroscopiaderessonância magnética

Procedimentosortopédicos

r

e

s

u

m

o

Objetivo: Avaliarodiâmetrodostendõesflexoresemexamesderessonânciamagnética (RNM)pré-operatóriaecompararcomodiâmetrodoenxertoobtidonoatointraoperatório.

Métodos: Emum estudo epidemiológicolongitudinal retrospectivo,44 pacientesforam elegíveisaoestudoetiveramosexamesdeRNMedadosdecirurgiasavaliados.Ostendões forammedidosnaRNMnoseumaiordiâmetronoplanoaxialcomousodoepicôndilo medialdofêmurcomoníveldecorte.Nacirurgiafoifeitopreparoderotinadoenxerto, dobraram-seostendõesgrácilesemitendinoso,formou-seumenxertoquádruploqueteve suamedidaregistrada.

Resultados: Paraaavaliaçãodaassociaçãoentreasvariáveisfoiestimadoocoeficientede correlaçãodePearson.Foiencontradacorrelaçãosignificativaentreasmedidasdostendões grácilesemitendinosoeodiâmetrofinaldoenxerto(p<0,001).Ajustou-seumacurvaROC paraasomadodiâmetrodostendões,paraadeterminaçãodeumpontodecorteassociado aodiâmetrodoenxerto(≤8mmou>8mm).Casoasomasejamaiordoque5,28mm,a chancedeobterumenxertomaiordoque8mméde75%.

Conclusão: AmedidadodiâmetrodostendõesgrácilesemitendinosonoexamedaRNM pré-operatóriaéumamaneirasimpleseeficaznapredic¸ãodotamanhofinaldoenxertoa serusadonacirurgiadereconstruc¸ãodoLCA.

Introduction

Ruptureofthe anteriorcruciateligament(ACL)isthemost commonkneeligamentousinjury,affectingover100,000 peo-ple annually in the United States. Its incidence has been increasingduetoagreaterstimulustoandpracticeofsports bythepopulation.1,2

TheACLoriginatesintheposteriorportionofthelateral femoralcondyle and inserts laterallyand anteriorly tothe medialtibialspine.Itfeaturesanintra-articularand extrasyn-ovial course, with a mean length of 38mm and a mean diameterof11mm.3–5

Currently,itisknownthattheACLiscomposedoftwosets offibersorbands:oneanteromedial(AM)andanother pos-terolateral(PL).Atthefemoralorigin,theAMbandemerges moreproximallyandposteriorly,whilethePLbandemerges moredistallyandanteriorly.Thebandsaretwistedalongtheir pathintheintercondylezone,andthetibialinsertionfollows theorderwhichgivesthemtheirname:anteromedialforthe AMandposterolateralforthePL.5–8

Surgicaltreatmentbasedonligamentreconstructionis rec-ommendedformostACLinjuries.Currently,thereareseveral optionsforgraftstoreplaceit;theflexortendons (semitendi-nosusandgracilis),patellartendon,andquadricepstendon aremostused.2,9_Choice_should_consider_profile_and_patients’ age,typeofsport,associatedlesions,andsurgeons’ experi-ence.Theidealgrafthasnotbeendefinedyet;somestudies showthatgraftswithdiameterslessthan7mmareassociated withahigherchanceoffailureandrelapse.10–13

Along with the advancement of imaging, preoperative measurementofthe diameter ofthe tendonson magnetic

resonance imaging (MRI) is possible, which is the gold standardimagingstudyforthediagnosisofthisinjury, allow-inganobjectiveparameterforthegrafttobechoseninACL reconstructionpriortosurgery.1,2,14–20

Thisstudyaimedtoevaluatethediameteroftheflexor ten-donsonpreoperativeMRIandcomparewiththediameterof thegraftobtainedintraoperatively.

Material

and

methods

AfterapprovalbytheReseachEthicsCommitteethroughthe Platform Brazil website, under the Certificate of Presenta-tionforEthicalAssessment(CertificadodeApresentac¸ãopara Apreciac¸ão Ética [CAAE])No.39346814.4.0000.0020, 100MRI scansanddatafromsurgeriesperformedbetween2012and 2014werecollectedandreviewedforthisretrospective, longi-tudinal,epidemiologicalstudy.

Inclusion criteria comprised skeletally mature patients withcompleteACLinjuryandnohistoryofpreviousligament or degenerative injuries. Exclusion criteria were: previous surgery, ligamentous laxity, chronic use of steroids, and dysplasia of the intercondylar notch (width of the distal femur/condylarfossa<0.2).

Aftersubjectselectionaccordingtoinclusionandexclusion criteria,44patientswereeligibleforthestudy.

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Fig.1–Measurementofdiameterofthesemitendinosus andgracilistendons.

attheirlargestdiameterintheaxialplane,consideringthe medialepicondyleofthefemurasthecutofflevel(Fig.1).

Duringsurgery,tendonswereremovedbystandardfashion techniquethroughaclosedtenotomy.Graftwaspreparedas usual:thegracilisandsemitendinosustendonswerefolded, formingaquadruplegraft.Thepreparedgrafthadits diame-termeasuredbeforedrillingthebonetunnelsinthetibiaand femur.Thesedatawererecordedatthesurgicalreportofthe patients.

Statisticalanalysis

Toevaluatetheassociationbetweenvariables,Pearson’s cor-relationcoefficientwasestimated.Theassessmentoftheuse ofthegracilisandsemitendinosusvariablesaspredictorsof graftdiameterwasmadethroughsimpleandmultiplelinear regressionmodels;toassesstheassociationofthesumofthe gracilisandsemitendinosuswiththeprobabilitythatthegraft diameterwasgreaterthan8mm,alogisticregressionmodel wasadjusted.Wald’stestwasusedtoassessthesignificance ofthecoefficients.

Regardingthesumofthegracilisandsemitendinosusfor determining a cutoff point associated with graft diameter (≤8mmor>8mm),aROCcurvewasadjusted.p-values<0.05 wereconsideredtobestatisticallysignificant.

DatawereanalyzedwithIBMSPSSv.20.0.

Results

Ofthe44patientsstudied,33weremale(75%)and11female (25%).Agerangedfrom 11to54 years,withamean of31.8 years.

Table1–Graftdiameter.

Graftdiameter n %

6 1 2.3

7 3 6.8

8 24 54.5

9 14 31.8

10 2 4.5

Total 44 100

MeandiameterofthegracilistendononMRIwas2.17mm, rangingfrom 1.45 to2.76mm, whilemeandiameter ofthe semitendinosuswas2.96,rangingfrom2.52to3.73mm.

During surgery,mean sizeofgrafts usedforACL recon-structionwas8.3mm,rangingfrom6to10 mm(Table1).

Fig.2showsthescatterplotgraphofthesemitendinosus and gracilisvariables,highlightingthe differenceof coordi-natesaccordingtothediameterofthegraft.

Datacorrelation

Gracilis×graftdiameter

Pearson’scorrelationcoefficientwasestimatedtobe0.59,and the test resultwas statistically significant (p<0.001). Thus, therewasasignificantcorrelationbetweenthegracilisand graftdiameter.Fig.3presentsthescatterplotofbothvariables. Eachpointcorrespondstoonecase.

Semitendinosus×graftdiameter

Pearson’scorrelationcoefficientwasestimatedtobe0.59,and the test resultwas statistically significant (p<0.001). Thus, there was asignificant correlation betweenthe semitendi-nosusandgraftdiameter.Fig.4presentsthescatterplotof bothvariables.Eachpointcorrespondstoonecase.

Sumofgracilis+semitendinosus×graftdiameter

Pearson’scorrelationcoefficientwasestimatedtobe0.74,and the test resultwas statistically significant (p<0.001). Thus, therewasasignificantcorrelationbetweenthesumof gra-cilis+semitendinosusandgraftdiameter.Fig.5presentsthe scatterplotofbothvariables.Eachpointcorrespondstoone case.

2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4

2.9 2.7 2.5 2.3 2.1 1.9 1.7 1.5 1.3

Semitendinosus

Gracilis

Diam 6 Diam 7 Diam 8 Diam 9 Diam 10

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Table2–Gracilis+semitendinosusasapredictorofgraftdiameter.

Diameterestimatedbythemodel Diameterobservedinthesample

6 7 8 9 10

n % n % n % n % n %

6 0 0% 0 0% 0 0% 0 0% 0 0%

7 1 100% 1 33.3% 2 8.3% 0 0% 0 0%

8 0 0% 2 66.7% 19 79.2% 6 42.9% 0 0%

9 0 0% 0 0% 3 12.5% 8 57.1% 1 50%

10 0 0% 0 0% 0 0% 0 0% 1 50%

Total 1 100% 3 100% 24 100% 14 100% 2 100%

3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2

Gracilis 5

6 7 8 9 10 11

Intra-operative graft

Pearson’s correlation coeficiente: 0.59 (P<.001)

Fig.3–Gracilis×graftdiameter.

Pearson’scorrelationcoefficientforbothtendonsshowed amoderatepositivecorrelationpower,whichindicatesa ten-dencythatthe largerthediameter ofthe patients’tendon, thegreaterthe finaldiameterofthe graftobtainedforACL reconstruction.

Assessmentofthequalityofthesumof

gracilis+semitendinosusasapredictorofgraftdiameter Toevaluatethesumofgracilis+semitendinosusasa predic-torofgraft diameter,asimplelinearregressionmodelwas

3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0

Semitendinosus 5

6 7 8 9 10 11

Fig.4– Semitendinosus×graftdiameter.

adjusted, and the sum was considered as an explanatory variable (independent)andthe diameterofthegraft asthe responsevariable(dependent).Theadjustedmodelwas:

Estimated diameter=2.618+1.107 (gracilis+ semitendinosus).

Theestimateddiameterforeachsinglevalueofthesum ofgracilis+semitendinosusshouldberoundedtothenearest integer.Forexample,foraparticularcasewhosesumof gra-cilis+semitendinosusisequalto6.51,theestimatedvalueof thediameterwillbe:

Estimateddiameter=2.618+1.107×6.51=9.82.

Theresultdiametertobeconsideredisequalto10. Basedon the study sample,Table2 presentsthe scores obtainedwiththemodelforeachparticulargraftdiameter.

Asaresultofinterest,thedeterminationcoefficientwas 55%.Thus,itwasestimatedthat55%ofthediameter varia-tionswereexplainedbythegracilis+semitendinosus.

Assessmentofthequalityofthesumof

gracilis+semitendinosusasapredictorofgraftdiameter ≤8mmor>8mm

The analysis presented below aimed to evaluate whether thesumofgracilis+semitendinosuswoulddiscriminatewell betweengraftdiameter≤8mmor>8mm.

Alogisticregressionmodelwasadjusted,consideringthe sumofgracilis+semitendinosusastheexplanatoryvariable

6.6 6.4 6.2 6.0 5.8 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8

Gracilis+Semitendinosus 5.5

6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5

Fig.5–Sumofgracilis+semitendinosus×diameterofthe

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Table3–Probabilityofgraftdiameter.

Gracilis+semitendinous Probabilityofgraftdiameter

greaterthan8mm

3.5 0.001

4 0.005

4.5 0.035

5 0.201

5.5 0.632

6 0.922

6.5 0.988

7 0.998

andthediameterofthegraft(≤8mmor>8mm)asthe

depend-entvariable.Thenullhypothesisthatthereisnoassociation betweenthesumgracilis+semitendinosusandtheprobability thatthegraftdiameteris>8mmwastestedagainstthe alter-nativehypothesisthatthereissuchanassociation.Thetest resultindicatedtherejectionofthenullhypothesis(p=0.001) andindicatedthatthesumofgracilis+semitendinosus sig-nificantlyinfluencestheprobabilitythatthegraftdiameteris >8mm.

Table3and Fig.6presentthe valuesofthe sumof gra-cilis+semitendinosusandtherespectiveprobabilitythatthe graftdiameteris>8mm,estimatedbytheadjustedmodel.

Determinationofacutoffpointforthesumof gracilis+semitendinosusthatisassociatedwithgraft diameter≤8mmor>8mm(ROCcurve)

A ROC curve was adjusted for the sum of gra-cilis+semitendinosus and considered the diameter of the graft(≤8mmor>8mm).Theareaunderthecurvewas0.87, withstatisticalsignificance(p<0.001).Thisindicatesthatthe curve fit is good and the sum of gracilis+semitendinosus discriminateswellbetweendiameter≤8mmor>8mm.

The optimal cutoff point for the sum of gra-cilis+semitendinosus was equal to 5.28, with sensitivity of75%andspecificityof85.7%.Table4presentstheseresults. Sensitivity: probability that the sum of gra-cilis+semitendinosus is >5.28 if the graft diameter is >8mm.

0.0 0.2 0.4 0.6 0.8 1.0

Probability of graft diamete

r>

8

4

3.5 4.5 5 5.5

Gracilis+Semitendinosus

6 6.5 7

Fig.6– Probabilityofgraftdiameter.

Table4–Sensitivityandspecificityaccordingtothe cutoffpoint.

Gracilis+semitendinosus Graftdiameter(mm)

≤8 >8

≤5.28 24 4

85.7%(specif) 25%

>5.28 4 12

14.3% 75%(sensit)

Total 28 16

Specificity: probability that the sum of gra-cilis+semitendinosus is ≤5.28 if the graft diameter is

≤8mm.

Fig.7showstheadjustedROCcurve.

Fig.8presentsthesensitivityandspecificityvaluesfor var-iousvaluesofthesumofgracilis+semitendinosus.

Discussion

Inthisstudy,asignificantcorrelationwasobservedbetween themeasurementsofthediameterofthetendonsonMRIand thesizeobtainedinsurgery.

Nostudieswereretrievedintheliteratureinwhich mea-surementswere madein asimilarway, i.e., measuringthe tendons ofthe semitendinosusand gracilisattheirlargest diameterintheaxialplanewiththecutofflevelatthemedial femoralepicondyle.

Beyzadeogluetal.1_observed_statistical_significance_in_the measurementofthecross-sectionalareaoftheflexortendons measuredattwolevelsonMRIandgraftsizeobtained intra-operativelyin51patients.Thediameterswerealsomeasured atthesetwolevels. However,nosignificantcorrelationwas observed.

Inasimilarstudy,Bickeletal.19_observed_a_significant cor-relationbetweenthesumofthesemitendinosusandgracilis areas measuredonMRIwithvaluesabove18mm2 _and _the

achievementofasuitable-sizedgraftin88%ofcases.

1.0

0.8

0.6

0.4

0.2

0.0

0.6 0.4

0.2 0.0

1-specificity

Sensitivity

1.0 0.8

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0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

6.4 6.2 6.0 5.8 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8

Sensitivity/specificity

Gracilis+Semitendinosus

Sensitivity

Specificity

5.28

Fig.8–Sensitivityandspecificityforvariousvaluesofthe sumofgracilis+semitendinosus.

In another study, Wernecke et al.16 _examined _the _area ofthe tendonsof34 patientson MRIand recommended a 10mm2_-area_for_the _gracilis_tendon_and _a₁₇_mm2_-area _for

thesemitendinosustendontoobtainasuitablesized graft, consideringaquadruplegraft.

Hamadaetal.18_measured_the_{semitendinosus}_area_at_MRI in79patientsanddemonstratedthat,whentheareaislarger than11mm2_,_a_graft_greater_than_or_equal_to₇_mm_is_achieved

duringsurgeryin89%ofcases.

Differently,Yasumotoetal.20_showed_that_prediction_of_the graftsizeispossiblebyexaminingthree-dimensional com-putedtomographyin28patients.

Otherstudieshaveattemptedtopredictthechanceof fail-ure in ACL reconstruction using data suchas gender, age, weight, height,and bone massindex (BMI). These studies, in general, have shown that eutrophic (>50kg) and short (>140–147cm)womenaremorelikelytohavegraftssmaller than7mm.9,13,15

Magnussenetal.10_analyzed_graft_size_and_age_of_patients aspredictors ofearly revisionACL reconstruction. Authors demonstratedthattheuseofgraftssmallerthanorequalto 8mmandpatientsyoungerthan20yearsareassociatedwith higherratesofrevisionsurgery.

Inthepresentstudy,wedemonstratedthatpredictionof thegraftsizethatwillbeobtainedforACLreconstructionis possiblebymeasuringthediameterintheaxialplanewiththe cutofflevelatthemedialfemoralcondyle.

Throughmeasurementsand theproposedalgorithm, an estimateddiameterof2.618+1.107(gracilis+semitendinosus) canindicatetheapproximategraftsize.

Anothermethodtoassesswhetherthegraftwillhavean appropriatesizeissummingthediametersofthetendons.If sumofgracilis+semitendinosusisgreaterthan5.28mm,the probabilityofobtainingagraftgreaterthan8mmis75%.

Probably,withagreaternumberofcases,especiallythose withgraftssmallerthanorequalto7,resultswillbeevenmore accuratetopredictgraftdiameter.

Conclusion

Thisstudydemonstratedthatmeasuringthediameterofthe gracilisandsemitendinosustendonsonpreoperativeMRIis asimpleandeffectivemethodtopredictthefinalsizeofthe grafttobeusedinACLreconstructionsurgery.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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